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gthomann


Oct 19, 2010, 11:32 AM
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Sewing your own slings
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I have seen previous threads in 2001 & 2004 on sewing slings but am starting a new one. I have always been interested in sewing slings; I once tried with my 30 year old Kenmore but was not very successful. Recently I got a Brother Project Runway PC-420 computerized machine and decided to try again. I bought some SpiderWire Stealth Braid spectra 10 lb test fishing line. Its diameter is about 0.01 inch, supposedly about the maximum diameter thread you can use on a home machine. I got the braided line because it seemed to be the most flexible.

I used regular 1 inch tubular webbing. I started with a No 8 needle and broke it and switched to a No 10. I used a zig zag stitch and tried stitching both across the webbing and parallel to the edge. The webbing is pretty bulky and initially I had some problems but by sewing slowly I got to where I could stitch without any problems.

The problem in making slings is testing; it is hard to figure out a way to put one or two thousand pounds of force on them. So what I did was make some loops with just a small amount of stitching and test them using my 180 lb body (in the living room, not on the cliff). The attached picture shows a test loop with 37 stitches; it held my weight with no problem. The red webbing with the loop on the end is a finished project; it has a couple of hundred stitches. I am not making slings to fall on, just stuff for top roping. After my testing I have complete confidence in the loop on the red webbing.
Attachments: slings.jpg (137 KB)


acorneau


Oct 19, 2010, 12:12 PM
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Re: [gthomann] Sewing your own slings [In reply to]
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gthomann wrote:
I have seen previous threads in 2001 & 2004 on sewing slings but am starting a new one. I have always been interested in sewing slings; I once tried with my 30 year old Kenmore but was not very successful. Recently I got a Brother Project Runway PC-420 computerized machine and decided to try again. I bought some SpiderWire Stealth Braid spectra 10 lb test fishing line. Its diameter is about 0.01 inch, supposedly about the maximum diameter thread you can use on a home machine. I got the braided line because it seemed to be the most flexible.

I used regular 1 inch tubular webbing. I started with a No 8 needle and broke it and switched to a No 10. I used a zig zag stitch and tried stitching both across the webbing and parallel to the edge. The webbing is pretty bulky and initially I had some problems but by sewing slowly I got to where I could stitch without any problems.

The problem in making slings is testing; it is hard to figure out a way to put one or two thousand pounds of force on them. So what I did was make some loops with just a small amount of stitching and test them using my 180 lb body (in the living room, not on the cliff). The attached picture shows a test loop with 37 stitches; it held my weight with no problem. The red webbing with the loop on the end is a finished project; it has a couple of hundred stitches. I am not making slings to fall on, just stuff for top roping. After my testing I have complete confidence in the loop on the red webbing.


I do believe the most appropriate response would be...

"Yer gunna die!"


That being said, I'm glad you're interested in something climbing related like sewn slings.

Assuming your interest lies in the process and the engineering behind the process, and not just a desire to save money, why not contact some of the smaller companies that sew climbing gear (like Yates, Mountain Tools, Misty Mountain, etc.) and ask them some specific questions as to why things are done the way they are done in the professional gear manufacturing world. You might get some great insight and information.

Honestly, it would suck very much if you were to get hurt or killed by something you thought you had figured out.

Good luck.


(This post was edited by acorneau on Oct 19, 2010, 12:25 PM)


gmggg


Oct 19, 2010, 12:26 PM
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Make sure you use a blunt needle so that you are displacing the nylon weave and not ripping through it.


jt512


Oct 19, 2010, 7:30 PM
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gthomann wrote:
I have seen previous threads in 2001 & 2004 on sewing slings but am starting a new one. I have always been interested in sewing slings; I once tried with my 30 year old Kenmore but was not very successful. Recently I got a Brother Project Runway PC-420 computerized machine and decided to try again. I bought some SpiderWire Stealth Braid spectra 10 lb test fishing line. Its diameter is about 0.01 inch, supposedly about the maximum diameter thread you can use on a home machine. I got the braided line because it seemed to be the most flexible.

I used regular 1 inch tubular webbing. I started with a No 8 needle and broke it and switched to a No 10. I used a zig zag stitch and tried stitching both across the webbing and parallel to the edge. The webbing is pretty bulky and initially I had some problems but by sewing slowly I got to where I could stitch without any problems.

The problem in making slings is testing; it is hard to figure out a way to put one or two thousand pounds of force on them. So what I did was make some loops with just a small amount of stitching and test them using my 180 lb body (in the living room, not on the cliff). The attached picture shows a test loop with 37 stitches; it held my weight with no problem. The red webbing with the loop on the end is a finished project; it has a couple of hundred stitches. I am not making slings to fall on, just stuff for top roping. After my testing I have complete confidence in the loop on the red webbing.

So, let me see I've got this right: You guessed at the type of thread to use, you guessed at the type of stitch to use, you guessed at the number of stitches to use—and then you tested it under body weight. That about right?

Jay


Express


Oct 19, 2010, 8:33 PM
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Yeah, there is actually some science behind textiles engineering. Different stitch types and lengths have different strength, based on a few different factors. My buddy designs military tents for a living and there is a whole design process to ensure the stitching and the material together provide the required strength for the application.


moose_droppings


Oct 19, 2010, 9:37 PM
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Express wrote:
Yeah, there is actually some science behind textiles engineering. Different stitch types and lengths have different strength, based on a few different factors. My buddy designs military tents for a living and there is a whole design process to ensure the stitching and the material together provide the required strength for the application.

Russ?

You trolling us?


marc801


Oct 19, 2010, 9:41 PM
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gthomann wrote:
I am not making slings to fall on, just stuff for top roping.
Which means you have no fucking clue about what you're doing.

gthomann wrote:
After my testing I have complete confidence in the loop on the red webbing.
I don't, nor does anyone sane who has even a minimal understanding of the forces involved in climbing. Here's hoping you don't kill any unsuspecting partners. You on the other hand appear to be a contender for a Darwin award.


russwalling


Oct 19, 2010, 11:29 PM
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moose_droppings wrote:
Russ?

You trolling us?

I wouldn't say that dude is "gonna die".....

I would say he is "already dead".

(T1- at best)


jt512


Oct 20, 2010, 12:25 AM
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russwalling wrote:
moose_droppings wrote:
Russ?

You trolling us?

I wouldn't say that dude is "gonna die".....

I would say he is "already dead".

(T1- at best)

Ugh. It's so obvious in retrospect.

Jay


wiki


Oct 20, 2010, 12:56 AM
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I would start by actually looking at a sewn sling... The stitching goes the other way mostly...

Get it pull-tested... report the results.


ozoneclimber


Oct 20, 2010, 1:42 AM
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OK.......

The obvious question:
Why not just use tubular webbing and a water-knot? You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B


sandstoned


Oct 20, 2010, 6:38 AM
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Ah, just a bunch of haters for no good reason. I doubt they really care about your safety anyway; they probably just want to be able to say "Hah, told ya so!" I say go for it, but back it up of course, twice, with some webbing purchased from a reliable manufacturer. Done with patience, diligence, and a small bit of intelligence, there is no reason not to pursue making your own gear.


Express


Oct 20, 2010, 9:15 AM
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sandstoned wrote:
Ah, just a bunch of haters for no good reason. I doubt they really care about your safety anyway; they probably just want to be able to say "Hah, told ya so!" I say go for it, but back it up of course, twice, with some webbing purchased from a reliable manufacturer. Done with patience, diligence, and a small bit of intelligence, there is no reason not to pursue making your own gear.

I'm not saying the OP shouldn't give an earnest go at making his/her own gear, it's that if you're going to do something your life potentially depends on, you should do it right. As some others have said, the stitching usually runs perpendicular (in several parallel tacks) to the direction of tensile forces in the sling. The way it's set up now, if the stitching begins to fail, it could cascade until the whole thing pulls apart. With isolated bar tacks, you'll have redundancy in the system.

What's the point of carrying a load of extra gear up the route if you can make one piece that will do the job right? By all means go for building your own stuff, it's been done many, many times in the past, but, for your own sake, do your homework first and do it right.


jt512


Oct 20, 2010, 10:16 AM
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russwalling wrote:
moose_droppings wrote:
Russ?

You trolling us?

I wouldn't say that dude is "gonna die".....

I would say he is "already dead".

(T1- at best)

Never overestimate your audience, Russ.

Jay


rock_fencer


Oct 20, 2010, 10:24 AM
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actually the bartacking on my arcteryx harness belay loop has 2 strands like that. But i get the feeling that a bartack is slightly different from a normal zig-zag stick on the home sewing machine.

T


erisspirit


Oct 20, 2010, 11:02 AM
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jt512 wrote:
gthomann wrote:
I have seen previous threads in 2001 & 2004 on sewing slings but am starting a new one. I have always been interested in sewing slings; I once tried with my 30 year old Kenmore but was not very successful. Recently I got a Brother Project Runway PC-420 computerized machine and decided to try again. I bought some SpiderWire Stealth Braid spectra 10 lb test fishing line. Its diameter is about 0.01 inch, supposedly about the maximum diameter thread you can use on a home machine. I got the braided line because it seemed to be the most flexible.

I used regular 1 inch tubular webbing. I started with a No 8 needle and broke it and switched to a No 10. I used a zig zag stitch and tried stitching both across the webbing and parallel to the edge. The webbing is pretty bulky and initially I had some problems but by sewing slowly I got to where I could stitch without any problems.

The problem in making slings is testing; it is hard to figure out a way to put one or two thousand pounds of force on them. So what I did was make some loops with just a small amount of stitching and test them using my 180 lb body (in the living room, not on the cliff). The attached picture shows a test loop with 37 stitches; it held my weight with no problem. The red webbing with the loop on the end is a finished project; it has a couple of hundred stitches. I am not making slings to fall on, just stuff for top roping. After my testing I have complete confidence in the loop on the red webbing.

So, let me see I've got this right: You guessed at the type of thread to use, you guessed at the type of stitch to use, you guessed at the number of stitches to use—and then you tested it under body weight. That about right?

Jay

What could possibly go wrong Unimpressed


gthomann


Oct 21, 2010, 6:20 AM
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gmggg, thanks for the information on needles; how did you know that? Are you a manufacturer? I actually used an Organ 90/14 universal so it has a slightly rounded point, although maybe not optimal.

The previous body weight test I did was with a loop. I did another test on just a single strand of webbing, picture included. I cut a piece of webbing in two, overlapped it and sewed it together. Each side has 20 stitches, 16 with 2 back stitches at each end to try to lock the thread. I tied one end to the pull up bar over the door, put my harness back on, clipped into the other end and weighted it. It didn't seem possible that those few stitches could hold 180 lbs, but they did; I sat suspended for about 30 s; the picture was taken after the test. Spectra is strong stuff!

PMI has released accessory cord that is sewn together at the ends, the middle item in the photo is a 6 mm cord from them. I sewed together a loop of 4 mm cord shown at the top; not quite as neat as the PMI job. It was somewhat hard to keep the stitches straight on the cord. This loop also held body weight.

That about concludes my experiments; I am done unless somebody wants me to try something particular. Back to work cleaning cliffs and finding climbs. Thanks to everybody that offered information.
Attachments: slings2.jpg (108 KB)


gmggg


Oct 21, 2010, 7:20 AM
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gthomann wrote:
gmggg, thanks for the information on needles; how did you know that? Are you a manufacturer? I actually used an Organ 90/14 universal so it has a slightly rounded point, although maybe not optimal.

The previous body weight test I did was with a loop. I did another test on just a single strand of webbing, picture included. I cut a piece of webbing in two, overlapped it and sewed it together. Each side has 20 stitches, 16 with 2 back stitches at each end to try to lock the thread. I tied one end to the pull up bar over the door, put my harness back on, clipped into the other end and weighted it. It didn't seem possible that those few stitches could hold 180 lbs, but they did; I sat suspended for about 30 s; the picture was taken after the test. Spectra is strong stuff!

PMI has released accessory cord that is sewn together at the ends, the middle item in the photo is a 6 mm cord from them. I sewed together a loop of 4 mm cord shown at the top; not quite as neat as the PMI job. It was somewhat hard to keep the stitches straight on the cord. This loop also held body weight.

That about concludes my experiments; I am done unless somebody wants me to try something particular. Back to work cleaning cliffs and finding climbs. Thanks to everybody that offered information.

No expertise whatsoever. Just looked into sewing this stuff before and have sewn a lot of clothes and upholstery.

I don't think it's quite the death sentence some of the above people make it out to be but I do think the utmost care is necessary. Here's some other observations:

1.) I'm not sure that the braided spectra would be the best thread to use. This is just a hunch though - based on likely wear to the stitch.

2.) Your stitches are really sloppy. A bartack is just a really tight zig-zag stitch but it it should be tight and ordered. You might try going slower when stitching or maybe your machine has a buttonhole setting. You also might try adding some appropriate adhesive between the webbing prior to sewing so that the piece is easier to handle.

3.) you should listen to people about rotating your stitch orientation 90 degrees. I believe someone used to make a screamer by essentially stitching webbing together the way you have. Of course that sling would have been correctly bartacked into a closed loop, your sling would just fail. Rotating the stitch should also make the piece easier to handle.

4.) Testing with bodyweight is completely meaningless. Figure out a way to conduct some "real" tests that can be replicated and have some degree of known or, at the very least, completely overestimated forces.


steinmethod


Oct 21, 2010, 7:55 AM
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gthomann wrote:
gmggg, thanks for the information on needles; how did you know that? Are you a manufacturer? I actually used an Organ 90/14 universal so it has a slightly rounded point, although maybe not optimal.

The previous body weight test I did was with a loop. I did another test on just a single strand of webbing, picture included. I cut a piece of webbing in two, overlapped it and sewed it together. Each side has 20 stitches, 16 with 2 back stitches at each end to try to lock the thread. I tied one end to the pull up bar over the door, put my harness back on, clipped into the other end and weighted it. It didn't seem possible that those few stitches could hold 180 lbs, but they did; I sat suspended for about 30 s; the picture was taken after the test. Spectra is strong stuff!

PMI has released accessory cord that is sewn together at the ends, the middle item in the photo is a 6 mm cord from them. I sewed together a loop of 4 mm cord shown at the top; not quite as neat as the PMI job. It was somewhat hard to keep the stitches straight on the cord. This loop also held body weight.

That about concludes my experiments; I am done unless somebody wants me to try something particular. Back to work cleaning cliffs and finding climbs. Thanks to everybody that offered information.


Please keep your home made gear at "HOME". If you plan on using this at the crag, you might want to warn others!!!


shoo


Oct 21, 2010, 8:06 AM
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Have you ever seen someone given a wedgie so hard they were lifted off the ground?

That is the equivalent level of strength testing you have given to your homemade slings.


Dirtdart


Oct 21, 2010, 8:18 AM
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Great job! I'm impressed. The money you've saved over purchasing pre-made slings should more than cover the cost of your funeral.


acorneau


Oct 21, 2010, 9:36 AM
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Dirtdart wrote:
Great job! I'm impressed. The money you've saved over purchasing pre-made slings should more than cover the cost of your funeral.


The OP never stated that he was doing this to save money.


Another thought for the OP:
You could always tie the webbing with a water knot with very short tails and then do a single line of stitching on the tails to keep the knot from untying. Sort of like what Metolius does for their Prusik cord set:
http://www.metoliusclimbing.com/prusik_cord_set.html


markc


Oct 21, 2010, 10:31 AM
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shoo wrote:
Have you ever seen someone given a wedgie so hard they were lifted off the ground?

That is the equivalent level of strength testing you have given to your homemade slings.

+1

I have a couple of friends who were killing time at work. They started experimenting with keychain biners to see how much weight they'd take. It took both of them bouncing on one to kill it. When it was just 350+ pounds sitting on it, the jive biner held fine. In climbing, body-weight tests are worth next to nothing.

Have it pull-tested. If you can't do that, devise a system where you can put real-world climbing forces on it, but where its failure won't compromise safety. The real problem is that your work isn't consistent. As such, your results won't be, either.


the_climber


Oct 21, 2010, 10:39 AM
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The Beer Knot is also another great alternative with no tails to get in the way.

As for sewing load bearing sling. I have access to some of the proper equipment, but even with that there are limitations, for example the bar tacker I use isn't 42 stitch, and has a slightly different pattern than those most commonly used for climbing. I'll use that for making slack line sling, not climbing slings. Only exception is some of the slings on the hooks I use aiding, however I use extra bar tacks for those.

As for repairing equipment, and haulable items, I've always been a fan of box stitching with #69 or #92 Bonded Nylon thread. Like I said though I have access to some equipment that most don't.


Khoi


Oct 21, 2010, 10:44 AM
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ozoneclimber wrote:
OK.......

The obvious question:
Why not just use tubular webbing and a water-knot?
You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B

gthomann

I'd really like to know your answer to this.


acorneau


Oct 21, 2010, 11:06 AM
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Khoi wrote:
ozoneclimber wrote:
OK.......

The obvious question:
Why not just use tubular webbing and a water-knot?
You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B

gthomann

I'd really like to know your answer to this.


Because he wants to make his own PTFTW's.
Wink

Why did some folks make a cam for the Lab cam contest? Curiosity, perhaps?


seatbeltpants


Oct 21, 2010, 12:09 PM
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acorneau wrote:
Khoi wrote:
ozoneclimber wrote:
OK.......

The obvious question:
Why not just use tubular webbing and a water-knot?
You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B

gthomann

I'd really like to know your answer to this.


Because he wants to make his own PTFTW's.
Wink

Why did some folks make a cam for the Lab cam contest? Curiosity, perhaps?

curiosity is cool - but how many of those who made cams for the contest actually climbed on them?

steve


Paul_W


Oct 21, 2010, 2:53 PM
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back in the day we used to sew our own slings. i made a complete set from 9/16 webbing and used poylester thread and an old sewing machine. i did take care to make sure the tension was right and inspected the bar tacks carefully. i took dozens of screamers on these and never had a problem. that said, the new gear is so light and nice why not pay a few bucks and buy some new slings, or if you can't afford that just use tied slings until you can afford some commercially sewn ones.


buck0land


Oct 23, 2010, 7:39 AM
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Re: [gthomann] Sewing your own slings [In reply to]
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What about contacting a master rigger for information on sew soft goods?


russwalling


Oct 23, 2010, 9:03 AM
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In reply to:
2.) Your stitches are really sloppy. A bartack is just a really tight zig-zag stitch but it it should be tight and ordered. You might try going slower when stitching or maybe your machine has a buttonhole setting. You also might try adding some appropriate adhesive between the webbing prior to sewing so that the piece is easier to handle.

A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)


bill413


Oct 23, 2010, 5:48 PM
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Re: [russwalling] Re:Sewing your own slings [In reply to]
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russwalling wrote:
In reply to:
2.) Your stitches are really sloppy. A bartack is just a really tight zig-zag stitch but it it should be tight and ordered. You might try going slower when stitching or maybe your machine has a buttonhole setting. You also might try adding some appropriate adhesive between the webbing prior to sewing so that the piece is easier to handle.

A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)

But this is a point worth getting out...thanks Russ.


oldrnotboldr


Oct 23, 2010, 8:44 PM
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Re: [acorneau] Sewing your own slings [In reply to]
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I saw a guy try to use homemade slings designed just like yours, it DID NOT HOLD EVEN ONE TOP ROPE FALL. Fortunately, the guys' set up was redundant and kept serious injury from happening. He rightly never used nor tried to self manufacture anymore.

Use commercial gear or the tried and true knotting methods. Otherwise "yer gonna die" and that is no exaggeration.


acorneau


Oct 24, 2010, 6:01 AM
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Re: [oldrnotboldr] Sewing your own slings [In reply to]
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oldrnotboldr wrote:
I saw a guy try to use homemade
slings designed just like yours...


I'm guessing that was intended for the OP and not me, right?

Wink


oldrnotboldr


Oct 24, 2010, 10:12 AM
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No, not you but the OP. That event was some years ago and the guy had the idea he could save some money. While the sling would hold static body weight, a fall ripped it faster than a screamer. I'm sure its possible to make your own but why. Considering the correct supplies, equipment, time, etc. it is not that cost effective. Plus, finding a way to properly test the final product. There are better, safer, cheaper, alternatives. I'm very nervous about any home made equipment.

As a side note to the OP--I hear that HomeDepot has some carabiners that would hold body weight also.


Adk


Oct 24, 2010, 5:34 PM
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["steinmethod wrote"]
In reply to:
Please keep your home made gear at "HOME". If you plan on using this at the crag, you might want to warn others!!!

I like this idea. Ummmm Gary? Please let me know when you are using one of those "Death Slings" if I happen to be on belay. I'd really rather leave the making of slings to the professionals.

Either you have been bored in your retirement or you are getting cheap. Curiosity killed the cat. At least it did in my neighborhood at one time or another. I don't want to see your name in the local headlines. If it is, you won't be in the "In memory of Section" here unless it here to poke fun at.

Yer Gunna Die!!!!Cool I ain't!

Well...I will eventualy but not at the hand of your sewing machine!Wink


gmggg


Oct 25, 2010, 7:39 AM
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Re: [russwalling] Re:Sewing your own slings [In reply to]
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russwalling wrote:
In reply to:
2.) Your stitches are really sloppy. A bartack is just a really tight zig-zag stitch but it it should be tight and ordered. You might try going slower when stitching or maybe your machine has a buttonhole setting. You also might try adding some appropriate adhesive between the webbing prior to sewing so that the piece is easier to handle.

A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)

Not trolling, I understand the stitch to be identical. I'd be interested to learn the difference if there's a resource you could point too or an explanation you could offer.


kennoyce


Oct 25, 2010, 7:56 AM
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Re: [seatbeltpants] Sewing your own slings [In reply to]
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seatbeltpants wrote:
acorneau wrote:
Khoi wrote:
ozoneclimber wrote:
OK.......

The obvious question:
Why not just use tubular webbing and a water-knot?
You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B

gthomann

I'd really like to know your answer to this.


Because he wants to make his own PTFTW's.
Wink

Why did some folks make a cam for the Lab cam contest? Curiosity, perhaps?

curiosity is cool - but how many of those who made cams for the contest actually climbed on them?

steve

I've climbed on homemade cams, Sungam has taken a fall onto one of my homemade cams, I think making and using your own gear is fine as long as you know what you are doing. The problem here is that the OP has shown that he really doesn't know what he is doing.


jt512


Oct 25, 2010, 9:39 AM
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kennoyce wrote:
seatbeltpants wrote:
acorneau wrote:
Khoi wrote:
ozoneclimber wrote:
OK.......

The obvious question:
Why not just use tubular webbing and a water-knot?
You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B

gthomann

I'd really like to know your answer to this.


Because he wants to make his own PTFTW's.
Wink

Why did some folks make a cam for the Lab cam contest? Curiosity, perhaps?

curiosity is cool - but how many of those who made cams for the contest actually climbed on them?

steve

I've climbed on homemade cams, Sungam has taken a fall onto one of my homemade cams, I think making and using your own gear is fine as long as you know what you are doing.


The problem is, as research has shown, people who don't know what they are doing, don't know that they don't know what they are doing.

Jay


(This post was edited by jt512 on Oct 25, 2010, 4:20 PM)


ClimbOn68


Oct 25, 2010, 5:32 PM
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Jay, your reply is FUNNY AS HELL! Soo True!


dynosore


Oct 25, 2010, 6:06 PM
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If you want a couple pull tested PM me. I can throw them on the Instron.


rockvoyager


Oct 25, 2010, 6:09 PM
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Re: [ClimbOn68] Sewing your own slings [In reply to]
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Several years ago I had a friend sew a twenty foot piece of 1 inch webbing together with 2 square boxes and with an x in the middle of the boxes. I cinch tied this to a telephone pole and then hooked the other end around a 2 inch hitch ball on my truck. For several minutes I tried to pull it apart. When I couldn't break it with a static pull I backed up about 2 feet and nailed it pretty good. Still did't break. after several tries I finally gave up because I was starting to bend my back bumper.

Having said that, I use store bought slings. There're cheap and dying would ruin my day.

Brad


jt512


Oct 25, 2010, 6:59 PM
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rockvoyager wrote:
Several years ago I had a friend sew a twenty foot piece of 1 inch webbing together with 2 square boxes and with an x in the middle of the boxes. I cinch tied this to a telephone pole and then hooked the other end around a 2 inch hitch ball on my truck. For several minutes I tried to pull it apart. When I couldn't break it with a static pull I backed up about 2 feet and nailed it pretty good. Still did't break. after several tries I finally gave up because I was starting to bend my back bumper.

Therefore, homemade slings are safe. Moreover, two box-X stitches are as good as 5 bartacks.

QED.

Jay


kennoyce


Oct 26, 2010, 5:51 PM
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jt512 wrote:
kennoyce wrote:
seatbeltpants wrote:
acorneau wrote:
Khoi wrote:
ozoneclimber wrote:
OK.......

The obvious question:
Why not just use tubular webbing and a water-knot?
You, and everyone else, know that it is tried and true. Why complicate things when you don't have to?

-B

gthomann

I'd really like to know your answer to this.


Because he wants to make his own PTFTW's.
Wink

Why did some folks make a cam for the Lab cam contest? Curiosity, perhaps?

curiosity is cool - but how many of those who made cams for the contest actually climbed on them?

steve

I've climbed on homemade cams, Sungam has taken a fall onto one of my homemade cams, I think making and using your own gear is fine as long as you know what you are doing.


The problem is, as research has shown, people who don't know what they are doing, don't know that they don't know what they are doing.

Jay

Great point as usual Jay. I certainly wasn't trying to say that this dude knows what he is doing (in fact based on his comments I believe that to be entirely untrue). I was merely pointing out that people do climb on homemade gear (not that I'm advocating doing this).


gmggg


Oct 27, 2010, 7:51 AM
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Re: [russwalling] Re:Sewing your own slings [In reply to]
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russwalling wrote:
In reply to:
2.) Your stitches are really sloppy. A bartack is just a really tight zig-zag stitch but it it should be tight and ordered. You might try going slower when stitching or maybe your machine has a buttonhole setting. You also might try adding some appropriate adhesive between the webbing prior to sewing so that the piece is easier to handle.

A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)

Bump.

Still wondering what difference there is between the two stitches, couldn't find much in my brief research on the topic.


gthomann


Oct 29, 2010, 8:08 AM
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Here are some results from initial testing. I have been using the loops I sewed in top rope setups but that isn't much of a test since the forces are so small. My CRV needed an oil change and John the garage owner is also a climber and of course I was showing him the webbing. So we decided to try lifting the back end of his truck. We tried first with the piece of webbing that only had 40 stitches. It lifted the truck quite a ways but then of course failed. So then we tried one of the "production" loops. The enclosed picture shows the setup with the back of the truck off the ground. The sewn loop is at the bottom connected to a quick link and the tied loop at the top goes to the caribiner. The photo is not very good; I did not have my tripod along and there was no way I was going to get in very close. We lowered the truck and inspected the equipment. The caribiner must have been bent a little as it no longer worked quite right.

After the lift test I photograped the loop as seen in the second picture. The stitching does not seem to have been stressed. You can see that the knot is pretty tight on the loop at the other end. I tried to undo the know with a marlin spike but I can't even get it started. The other small piece of webbing is what is left of the 40 stitch samplel.

Maybe it takes a 1000 pounds to lift the back end of the truck. John and I have already decided that at the next oil change we will try to lift the front end. I will take a tripod so we can get the camera in a little closer while we stand back.
Attachments: truck.jpg (118 KB)
  slings3.jpg (94.9 KB)


jt512


Oct 29, 2010, 8:43 AM
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gthomann wrote:
Here are some results from initial testing. I have been using the loops I sewed in top rope setups but that isn't much of a test since the forces are so small. My CRV needed an oil change and John the garage owner is also a climber and of course I was showing him the webbing. So we decided to try lifting the back end of his truck. We tried first with the piece of webbing that only had 40 stitches. It lifted the truck quite a ways but then of course failed. So then we tried one of the "production" loops. The enclosed picture shows the setup with the back of the truck off the ground. The sewn loop is at the bottom connected to a quick link and the tied loop at the top goes to the caribiner. The photo is not very good; I did not have my tripod along and there was no way I was going to get in very close. We lowered the truck and inspected the equipment. The caribiner must have been bent a little as it no longer worked quite right.

After the lift test I photograped the loop as seen in the second picture. The stitching does not seem to have been stressed. You can see that the knot is pretty tight on the loop at the other end. I tried to undo the know with a marlin spike but I can't even get it started. The other small piece of webbing is what is left of the 40 stitch samplel.

Maybe it takes a 1000 pounds to lift the back end of the truck. John and I have already decided that at the next oil change we will try to lift the front end. I will take a tripod so we can get the camera in a little closer while we stand back.

So you've been toproping on slings that may be have less than 1/5 the strength of a normal sling. You must be proud.

Jay


(This post was edited by jt512 on Oct 29, 2010, 8:45 AM)


spikeddem


Oct 29, 2010, 8:48 AM
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Gthomann, you keep saying the forces in a TR setup aren't much. I'm curious about the numbers you have for that. What forces have you observed?

I'd also be a bit surprised if it took a thousand pounds of force to lift the tail of a truck off the ground. Maybe if it was a pretty big truck with entirely too much junk in its trunk.


Rudmin


Oct 29, 2010, 9:08 AM
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spikeddem wrote:
Gthomann, you keep saying the forces in a TR setup aren't much. I'm curious about the numbers you have for that. What forces have you observed?

I'd also be a bit surprised if it took a thousand pounds of force to lift the tail of a truck off the ground. Maybe if it was a pretty big truck with entirely too much junk in its trunk.

That truck probably weighs around 5000 lbs. If the centre of gravity was halfway between the front wheel and the hitch, he would be pulling up 2500 lbs. Since it's probably forward of that, 1000 lbs sounds like a very reasonable conservative estimate.


dynosore


Oct 29, 2010, 9:14 AM
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Are you guys smoking crack? You think a full size truck is that light haha. Weight distribution is around 55/45 front/rear in a full size pickup. That truck weighs at least 5000 lbs. That means the back end "weighs" at least 0.45*5000 or 2250 lbs. 10kn minimum. That's for a empty, 2wd 1/2 ton. It's probably even heavier.


bigo


Oct 29, 2010, 9:26 AM
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jt512 wrote:
So you've been toproping on slings that may be have less than 1/5 the strength of a normal sling. You must be proud.

Jay

I don't think his 'tr quality' sling failed. He is calling his homemade sling with more stitches the 'production' sling. The one that failed is a 40 stitch joint that I think he was testing to try and get a strength per stitch from.

While I enjoy 'do it yourself projects', sewing your own slings seems like a strange one to take on. High risk - low reward.

gthomann wrote:
Maybe it takes a 1000 pounds to lift the back end of the truck.

Not sure how comfortable you are doing a little math, but if you found the center of gravity of the truck, you could derive a pretty good estimate of how much load you are putting on the sling using static beam analysis. The center of gravity of the truck is the balance point.

force = (dist_front_tire_CG/dist_hitch_CG)*truck_weight

edit: others beat me to the CG...


(This post was edited by bigo on Oct 29, 2010, 9:27 AM)


spikeddem


Oct 29, 2010, 9:31 AM
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dynosore wrote:
Are you guys smoking crack? You think a full size truck is that light haha. Weight distribution is around 55/45 front/rear in a full size pickup. That truck weighs at least 5000 lbs. That means the back end "weighs" at least 0.45*5000 or 2250 lbs. 10kn minimum. That's for a empty, 2wd 1/2 ton. It's probably even heavier.

Full size truck? Nobody ever mentioned a full size truck.


jt512


Oct 29, 2010, 9:45 AM
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bigo wrote:
jt512 wrote:
So you've been toproping on slings that may be have less than 1/5 the strength of a normal sling. You must be proud.

Jay

I don't think his 'tr quality' sling failed. He is calling his homemade sling with more stitches the 'production' sling. The one that failed is a 40 stitch joint that I think he was testing to try and get a strength per stitch from.

I know. He's been TRing on a sling that he only (now) knows can hold 1000 lb.

In reply to:
Not sure how comfortable you are doing a little math . . .

I think we can reliably guess the answer to that question.

Jay


bigo


Oct 29, 2010, 10:32 AM
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I read over the "may[ ]be have" part of your statement ... oh well, so much for reading comprehension.


gunkiemike


Oct 29, 2010, 2:10 PM
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gthomann wrote:
So what I did was make some loops with just a small amount of stitching and test them using my 180 lb body (in the living room, not on the cliff). The attached picture shows a test loop with 37 stitches; it held my weight with no problem.

How many stitches does it take to JUST hold your 180 lb body weight? That's a key bit of info. Then sew your sling with at least 30X that many stitches.


Adk


Nov 1, 2010, 1:57 PM
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This has made me thirsty and my bowl of popcorn is almost empty.

Majid showed that you can rap on just a few strands of the core of dynamic rope but that does not mean I want to do it or that I should.

I don't think Gary is serious about going into the manufacture of slings. I think he is just bored.....or I hope so anyway.Unsure
I hesitate to say...Trolling???

If he is not he needs to stop taking drugs.LaughLaugh


Adk


Nov 1, 2010, 2:00 PM
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This photo is no good without MAJID's arrows!!!!!

Wait one minute!!! Are those truck tires really off the ground? Unsure I see no air. It must be the angle right?
Just busting your chops Gary.


(This post was edited by Adk on Nov 1, 2010, 2:35 PM)


crackers


Nov 4, 2010, 3:37 PM
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gmggg wrote:
russwalling wrote:
A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)

Not trolling, I understand the stitch to be identical. I'd be interested to learn the difference if there's a resource you could point too or an explanation you could offer.

I think Google is a pretty good resource. Try googling something like Juki LK-1900 manual or similar. When you read the part in the manual about how the bartack is formed, you should start to get an idea about some of the differences...I'm sure if you paid Russ or myself we'd be happy to explain in excruciating detail, but I've got to hope we all have better things to do with our lives.


gunkiemike


Nov 4, 2010, 6:10 PM
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russwalling wrote:
A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)

But that doesn't mean you need bartacks to sew a sling. Mammut used to sell dogbones that clearly are just rows of stitching. Not even zig-zag. Just straight stitches in rows: 25 rows of 7 stitches in the one I have. Rated at 22 kN.


el_layclimber


Nov 4, 2010, 7:49 PM
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gunkiemike wrote:
gthomann wrote:
So what I did was make some loops with just a small amount of stitching and test them using my 180 lb body (in the living room, not on the cliff). The attached picture shows a test loop with 37 stitches; it held my weight with no problem.

How many stitches does it take to JUST hold your 180 lb body weight? That's a key bit of info. Then sew your sling with at least 30X that many stitches.

NO - not that I'm against this project, I see no reason why not to tool around with making his own gear as long as he exercises caution. However, I do know that one of the issues with sewing slings is that you don't want too many stitches - each time you push a thread through the webbing, you are displacing and possibly tearing the webbing itself - too many stitches, and you end up with a stitch that is strong, but you have weakened the material it is in.
On another note, didn't Dean Potter (whose intelligence I really appreciate) make himself a harness using supertape and dental floss for speed ascents of El Cap?


gmggg


Nov 5, 2010, 11:04 AM
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crackers wrote:
gmggg wrote:
russwalling wrote:
A bartack is NOT just a really tight zigzag. There is more to it than that. (note to self: do not feed the trolls)

Not trolling, I understand the stitch to be identical. I'd be interested to learn the difference if there's a resource you could point too or an explanation you could offer.

I think Google is a pretty good resource. Try googling something like [url=http://www.juki.co.jp/industrial_e/products_e/alldocument.html#products_e/apparel_e/cat87/lk1900a_lk1902a_lk1901a.html]Juki LK-1900 manual or similar. When you read the part in the manual about how the bartack is formed, you should start to get an idea about some of the differences...I'm sure if you paid Russ or myself we'd be happy to explain in excruciating detail, but I've got to hope we all have better things to do with our lives.

Well I took some time to look further into it since you don't have the ability to summarize the difference and I still fail to see what separates the two terms. Now I know I'm as dumb as a cantaloupe, but I can't seem to find any operating manuals for industrial bar tackers online(your link isn't complete). And what I did see is that the industrial machines are using a lock-stitch. Same as most home machines. So if the pattern is what differentiates zig-zag from bar-tack, what pray tell is the difference? I found the Juki stitch diagram here and I notice a line returning the stitch to the starting position, but it doesn't seem to lock in anywhere on the return.

Google I'm afraid may be fairly worthless since every page I've looked at has defined the bar-tack as a zig-zag.

Again, I'm not trying to prove anything, just curious about the subject.


Here's a full link to the diagram I found, RC.com seems to be inserting "%3D" into the url script for some reason:

http://www.juki.co.jp/...lk1902a_lk1901a.html


tugboat


Jul 19, 2011, 9:41 AM
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As others have mentioned a bartack is not a zigzag or vise versa....although they share some of the same stitch elements.

In basic terms a bartack is a 3 pass of a straight stich then the straight stich is captured by a zigzag over the top to the end....the end generally having a specific backstitch depending on how you program it.

A zig zag, by comparison is just that,...a zig zag stitch. Thus, it is missing the straight stitch component.

Bartacks are favourable in many climbing applications due to the fact that they put alot of strength in one area in fast (read production time) manner. As well, they are incredibly difficult to undo, whereas other stitches may have more propensity to start loosening or unravelling (but not neccessarily).

A bartack also combines two elements useful to strength stitiching; the straight component is considered a good "hold down" stitch, while the zig zag has expasion quailities. Although, in sewing climbing slings with bartacks, the expasion properties of the zig zag, don't really come in to play.

A zig zag stitch by itself has favourable properties, hence its use in certain safety sewing applications. Without the straight stitch component, the zig zag, under load, can expand an incradible amount if the stich is in the direction of the load or at least at 45 degress to it. If it is at 90 degrees the load it's expansion properties are generally negated.

The problem with one stitching their own slings in your case are many fold. Where to start?.... Lack of proper equipment (no you dont have to start with a bartacker), lack of knowledge of how to use said equipment, lack of knowledge of stitching (specifically safety sewing), lack of knowledge of materials and their interaction ot eachother,.....and most importantly,...lack of a good pull tester with load cell and data aquisition so you can understand whats going on with your differnet stitch attempts.

Remember also, there is more to safety sewing than just sewing, say, a sling and getting a good 'break number'. You need to know other dynamics of your product, stitch, and materials, to have a viable, useable product.

Anyway.... there is much more (years of learning) that one can go on about,....but i don't have enough coffee in me to bother too much more... Suffice it to say,... it takes years of learning and study (and even then there will always be people who know more that you) to get a grasp of safety sewing; Home sewing machines with blue jean needles and guessing at strength using Truck weight etc is not a good way to start.

Start by buying a copy of the "Parachute manual....a technical treaties on....", buying an indutrial striaght stitch machine for a couple hundred bucks,...and find a shop (marine, rigging supply shop) that is willing to break your many samples before you even think of climbing on them...

Just my opinion coming from 20 years of sewing for the safety industry. I own a Juki programable tacker, pfaff 138 zig zag, consew long arm 3 step zig zag with servo control, sunstar heavy needle feed, Sunstar
In reply to:
open arm needle feed binding attachment machine, Yakumo saddle machine (open arm), 18 foot enginered testing bed with sensotronic load cell and digital data aquistion, and a harness testing torso for the pull tester,....as well i work with pure spectra webbing, spectra and nylon broadcloths, and spectra and nylon thread.

peace.
In reply to:


(This post was edited by tugboat on Jul 19, 2011, 9:52 AM)


tugboat


Jul 21, 2011, 11:05 PM
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if you need more clarification on bartacking and different safety sewing, i don't mind attempting to help clarify more ...to the best of my abilities. Note; the juki lk1900 is a programmable with a selection of built in different stitch patterns.... so just looking at the manual won't help alot.

People do get hung up on the term "bartack'...like its some sort of magical, 'dark art' thing. its not. it is a stitch pattern that uses lock stitches. bartacks can have many variations on the theme...

The thing to keep in mind when it comes to sewing in general and safety gear is " use the right stitch for the right application". Sometimes production process and time/cost concerns will influence the choice....but they should never sacrifice safety.

questions are welcome... if i have the answer i don't mind sharing. Knowledge = safety.

peace.


gunkiemike


Jul 24, 2011, 6:02 AM
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tugboat wrote:

People do get hung up on the term "bartack'...like its some sort of magical, 'dark art' thing. its not. it is a stitch pattern that uses lock stitches. bartacks can have many variations on the theme...

Nor are bar tacks essential. I have in my hands here a Mammut dogbone that is sewn with nothing but 24 rows of straight stitches. UIAA rated piece, says 22 kN on the label.


JimTitt


Jul 24, 2011, 7:45 AM
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gunkiemike wrote:
Nor are bar tacks essential. I have in my hands here a Mammut dogbone that is sewn with nothing but 24 rows of straight stitches. UIAA rated piece, says 22 kN on the label.

A black one about 3/4" wide? I´ve some of those and they are getting on in life a bit (18 years old) and we tested some of these the other day along with some other brands. 18,6kN made it the best we´ed ever seen for an old dogbone and interestingly inside there are white fibres which we though may be Dyneema. Last week we got some hybrid Nylon/Dyneema tape samples in and one appears to be identical. 25kN single strand.

Jim


tugboat


Jul 24, 2011, 11:46 AM
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Agreed.... bartacks are not essential. Indeed in several ways that are not ideal. But they do have favourable characteristics for both the customer (from the companies vantage/liability) and from the manufacturer's side in terms of production. You need a tacker with a large field if you want do a programmed 5 point riser type pattern. Or if you want to do the riser pattern and dont have a capable tacker you would have to do it by hand.

But in terms of pure load dispertion and fabric integrity a 3 or 4 point riser stitch or just the straight row stitches (given narrow webbing) is technically better (if you weed out specific other factors that donbt have to do with strength). Spectra fiber might introduce exceptions to this rule, given its low coeffcient of friction,....thus a tack is nice to lock up that warp and weft tight.

Sewing the slings by something other than a tacker is time consuming and may, i repeat 'may', lack the quality control of a tack. One can get a single tack machine, get a jig built and be off to the races (well, not quyite that easy, you get the drift). It takes more skill to learn good 'riser' type sewing vs tacking in my opinion. And therefore it takes more teaching/learning for the company.

I think if people wonder about the commonality of the bartack, it may help to know that it orginallly came from the blue jean industry/ garment industry (correct me if i'm wrong...but quite sure im correct), and then was picked up by the climbing community for its production qualities.

Indeed, my first mechanical tacker was for the garment industry that ran a cam for pattern. Then you received the machine and had to "tweak" it for climbing sewing; decrese rpm (new clutch/motor pulley diameter, enlarge needle plate hole, bigger needle, retime cam, etc). The new electronic tackers are a Godsend. But the old tackers sure taught you alot whether you liked it or not!Tongue


(This post was edited by tugboat on Jul 26, 2011, 12:08 PM)


gmggg


Jul 26, 2011, 9:13 AM
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Thanks for the info! That's exactly what I was thinking but couldn't find any good resources at hand.

Very educational.


tugboat


Jul 26, 2011, 12:11 PM
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tugboat wrote:
Agreed.... bartacks are not essential. Indeed in several ways that are not ideal. But they do have favourable characteristics for both the customer (from the companies vantage/liability) and from the manufacturer's side in terms of production. You need a tacker with a large field if you want do a programmed 5 point riser type pattern. Or if you want to do the riser pattern and dont have a capable tacker you would have to do it by hand.

But in terms of pure load dispertion and fabric integrity a 3 or 4 point riser stitch or just the straight row stitches (given narrow webbing) is technically better (if you weed out specific other factors that donbt have to do with strength). Spectra fiber might introduce exceptions to this rule, given its low coeffcient of friction,....thus a tack is nice to lock up that warp and weft tight.

Sewing the slings by something other than a tacker is time consuming and may, i repeat 'may', lack the quality control of a tack. One can get a single tack machine, get a jig built and be off to the races (well, not quyite that easy, you get the drift). It takes more skill to learn good 'riser' type sewing vs tacking in my opinion. And therefore it takes more teaching/learning for the company.

I think if people wonder about the commonality of the bartack, it may help to know that it orginallly came from the blue jean industry/ garment industry (correct me if i'm wrong...but quite sure im correct), and then was picked up by the climbing community for its production qualities.

Indeed, my first mechanical tacker was for the garment industry that ran a cam for pattern. Then you received the machine and had to "tweak" it for climbing sewing; decrese rpm (new clutch/motor pulley diameter, enlarge needle plate hole, bigger needle, retime cam, etc). The new electronic tackers are a Godsend. But the old tackers sure taught you alot whether you liked it or not!Tongue

Sorry.... for the 'riser' pattern i meant you DO need a large field tacker....

and "sewing it by hand"....i meant straight stitch machine sew...not actually actually "by hands"!...

sorry about that, must have been late that night.


Rmsyll2


Aug 2, 2011, 8:42 PM
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I read this thread not long after it started, found a mention of using the X-Box that I knew from parachute rigging, and sewed my slings from 1" tubular, bought at $0.60/foot exactly to save money, using nylon upholstery thread. The box for mine is 4" long with a short stitch length, and the ends are doubled. I had bought a few slings (that do use bar-tacks), making a sewn one to match each of them, so that I've used one of each, or two sewn ones, with no problems during a few hundred top-rope climbs.

Tying any knot in any material weakens the material at the knot, according to various respected publications. It also makes a lump, and leaves tails either flopping around or needing more knots and lumps. My sewn slings are kept in a flattened roll so that they store compactly and come out looking new each time.

.


tugboat


Aug 5, 2011, 1:37 AM
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Rmsyll2 wrote:
I read this thread not long after it started, found a mention of using the X-Box that I knew from parachute rigging, and sewed my slings from 1" tubular, bought at $0.60/foot exactly to save money, using nylon upholstery thread. The box for mine is 4" long with a short stitch length, and the ends are doubled. I had bought a few slings (that do use bar-tacks), making a sewn one to match each of them, so that I've used one of each, or two sewn ones, with no problems during a few hundred top-rope climbs.

Tying any knot in any material weakens the material at the knot, according to various respected publications. It also makes a lump, and leaves tails either flopping around or needing more knots and lumps. My sewn slings are kept in a flattened roll so that they store compactly and come out looking new each time.

.

box-x pattern works fine too. It has its pros and cons over bartacks and other patterns.

There is usaully going to be a pro and con to each stitch pattern selected. eg the box x can possibly loosen more easily than bartacks. On the otherhand, it distributes force over a greater area of material using less stitch count....

If you have covered all the following steps, or are already a rated parachute rigger etc, excuse the following suggestion; its good to know for your box x exactly what they are worth load wise for a given stitch count/pattern. Otherwise your just guessing or estimating. If you dont have a pull tester, seek out a local marine shop that has one and is willing to do some breaks for you (if you haven't already). And while i know upholestry thread can be strong,...its not really a standard within the climbing sewing world. Either use 138 Nylon or is equivalent in parachute rigging standard notation...like size "FF" 8 oz, etc.


surfstar


Aug 5, 2011, 8:43 AM
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I'm a cheap @ss bastard, but at some point my time becomes worth money + add in my life on the line = I'll buy some BD nylon slings that can be found 20% off all the time and never have to worry.

But then we'd never have threads like this for entertainment. Homemade screamers - schweet.


splish


Jul 16, 2012, 12:25 PM
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A bar tack is a really tight zig zag, backed up on itself.

http://cyberseams.com/article/105109/basics/what_is_a_bartack_stitch.html

I could be wrong, but I am just going by what I learned at this site...


(This post was edited by splish on Jul 23, 2012, 12:04 PM)


splish


Jul 22, 2012, 11:05 PM
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Rudmin wrote:
spikeddem wrote:
Gthomann, you keep saying the forces in a TR setup aren't much. I'm curious about the numbers you have for that. What forces have you observed?

I'd also be a bit surprised if it took a thousand pounds of force to lift the tail of a truck off the ground. Maybe if it was a pretty big truck with entirely too much junk in its trunk.

That truck probably weighs around 5000 lbs. If the centre of gravity was halfway between the front wheel and the hitch, he would be pulling up 2500 lbs. Since it's probably forward of that, 1000 lbs sounds like a very reasonable conservative estimate.

I have a full size SUV, with straight axles, and it doesn't weight 5000 lbs. The weight of any vehicle is on the door. The truck has no weight in the back. In high school, me and 3 other guys used to lift the back of Jeff's truck off the ground and turn it sideways in the parking spot. The back of a truck is ridiculously light!!!
Lift the engine, then I will be impressed. But I don't understand why this guy doesn't test it the same way UIAA does, put a wieght on it and drop it! find a porch or balcony or something. And a sand bag or some dumb bell weights!


gunkiemike


Jul 28, 2012, 7:57 PM
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splish wrote:
L But I don't understand why this guy doesn't test it the same way UIAA does, put a wieght on it and drop it! find a porch or balcony or something. And a sand bag or some dumb bell weights!

Hey folks, looks like we have a gen-U-ine UIAA expert here!!


splish


Jul 28, 2012, 8:40 PM
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gunkiemike wrote:
splish wrote:
L But I don't understand why this guy doesn't test it the same way UIAA does, put a wieght on it and drop it! find a porch or balcony or something. And a sand bag or some dumb bell weights!

Hey folks, looks like we have a gen-U-ine UIAA expert here!!

Any idiot could watch a few videos and read a few specs and figure it out Mike. Sorry it's too complicated for you "science teacher"


JimTitt


Jul 28, 2012, 11:15 PM
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Perhaps gunkiemike was making fun at your expense as the UIAA do not drop-test slings.


splish


Jul 28, 2012, 11:30 PM
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JimTitt wrote:
Perhaps gunkiemike was making fun at your expense as the UIAA do not drop-test slings.

Yep, you are right. I am definately the idiot here.
I should have said pull testing.

I am sorry Mike. I know I am going to pay for this.

But hey, could be worse. I could have been the guy climbing in the zig zag stitch that supports 85Lbs...


JimTitt


Jul 29, 2012, 3:37 AM
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I just thought I ought to correct you for the benefit of future readers in 2020.


wivanoff


Jul 29, 2012, 5:33 AM
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splish wrote:
Lift the engine, then I will be impressed.

I used to sew my own slings BITD (1970s). Not because I was cheap, but because sewn climbing slings just weren't available. Most people just tied slings out of 1" tubular webbing with a water knot.

"Off Belay" magazine had an article about sewing your own slings. They showed stitching patterns (multiple rows parallel to the length of the sling), type of thread, stitches per inch, length of splice, etc. (edit: looks like the same article was also published by Cal Magnussen here http://www.caves.org/...ical/nhback/NH03.pdf)

I decided to try that. To see how well I did, I tested one of my sewn splices like this: I used two lengths of webbing. First ends were stitched, second ends were tied with a water knot. I attached the slings between the trailer hitches of two trucks with some steel cable for slack. Used 1/2" steel quick links and Bonatti "D" carabiners. Drove/rolled one truck away to see what would happen.

First test, the water knot broke inside the knot. I retied it. Second test, the water knot broke inside the knot. I retied it. Third test the Bonatti carabiner snapped. After that, I decided my stitching was "strong enough". True, it was a very small statistical sample, but I was pretty confident with what I saw.

Interesting experiment and I used those homemade sewn slings for a while. But, I've been buying sewn slings since they became widely available and it was no longer worth my time to sew.


(This post was edited by wivanoff on Jul 29, 2012, 11:15 AM)


splish


Jul 29, 2012, 8:05 AM
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JimTitt wrote:
I just thought I ought to correct you for the benefit of future readers in 2020.

No problem Jim. I was definately wrong.

I like your style. You didn't resort to insults, name calling or swearing. You simply sat back, let me make myself look stupid and simply pointed it out with a quick bit of wit at the end.
It shows class and intelligence. Kudos!
I have no problem being the butt of the joke when I made the mistake.


crasic


Jul 29, 2012, 9:52 AM
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JimTitt wrote:
Perhaps gunkiemike was making fun at your expense as the UIAA do not drop-test slings.

Indeed, slings aren't dynamic elements like rope, they don't get drop tested because in reality they shouldn't be dropped on without a dynamic element. And basically any static drop test will only be useful if you have a weight cell to measure the load before breakage.

FF1 (80kg) on double length dyneema will snap it half the time, FF2 on single or double length dyneema will snap it guaranteed. Assuming a direct fall on a static anchor with no dynamic element. Nylons fairs a little better. If op doesn't have a load cell, him dropping a weight on it would tell him no information as even commercial slings are liable to snap.

linky


JimTitt


Jul 29, 2012, 10:58 AM
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I´m English, we are brought up like that!

And I´ve a dog and recalcitrant machines to insult and shout abuse at, they love it.


splish


Jul 29, 2012, 6:07 PM
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crasic wrote:
JimTitt wrote:
Perhaps gunkiemike was making fun at your expense as the UIAA do not drop-test slings.

Indeed, slings aren't dynamic elements like rope, they don't get drop tested because in reality they shouldn't be dropped on without a dynamic element. And basically any static drop test will only be useful if you have a weight cell to measure the load before breakage.

FF1 (80kg) on double length dyneema will snap it half the time, FF2 on single or double length dyneema will snap it guaranteed. Assuming a direct fall on a static anchor with no dynamic element. Nylons fairs a little better. If op doesn't have a load cell, him dropping a weight on it would tell him no information as even commercial slings are liable to snap.

linky

Yeah, I know. I didn't mean to say drop test, when I wrote that I was just not thinking about what I was typing. I should have said pull test, but was thinking of drop test for some reason.
Thanks for the link, some things I knew, but the refresher was good, and some things I learned.


(This post was edited by splish on Jul 29, 2012, 6:09 PM)


splish


Jul 29, 2012, 6:37 PM
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In the mid 90's I was also curious about sewing slings. I did try it, but never had any intention of ever climbing on them.
I had sewn 3 slings, all roughly the same length, with a 5" overlap and a very simple pattern.
I don't know anything about threads and such, so I went to Fabricland, I showed the woman the webbing, and explained the purpose of it.
She sold me some higher end nylon thread and a proper needle she said would not tear the fabric, but instead separate the fibers allowing the thread to pass through without damaging the webbing.

Although I never climbed on them, I did try some very simple tests on them. Using the crane in the shop, I lifted various tools, starting with a Planer/Jointer that weighs in at 3500 lbs and working my way various larger tools till I reached the largest one we have in the shop that weighs in at 6745lbs.
The first sling broke lifting a 14" table saw with a net weight of 5600Lbs, the second sling broke when I lifted the same table saw with 600 lbs of plate steel on it. The third sling never broke and I didn't have anything larger to lift.
I left the sling in the work shop, and my father stole it and has been using it for various construction site needs since. The most impressive, removing a large tree stump. We were trying to pull in out using chains, but didn't have enough chain. First I used a piece of Blue Water 11mm Static line I had that had been retired, but it broke fairly easily. So we had the sling in the work van, and decided it was worth a go. We wrapped the stump in chain, a shackle connected the chain to the webbing, and another shackle from the webbing to the bob cat. I had tied a water knot in each end, so that may have helped some as the solid webbing may have took more of the force than the side that was sewn. We yanked and yanked, the sump did not move. We then resorted to putting slack in the line and then gunning it, putting a massive shock load on the whole system. After about 7 pulls like that, the stump came loose and we were able to remove it.
On the way home from work today, I stopped in to visit my parents, and because of this post, thought of that. Turns out my father still has the sling, and uses it from time to time for little tasks. Here are some images...







Unfortunately, I don't have access to a proper load cell, but I tell you, theis thing has stood up to some beatings. I would love to know what it would be rated at.


(This post was edited by splish on Jul 29, 2012, 9:05 PM)


gthomann


Jul 30, 2012, 4:58 AM
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Thats really impressive, especially with nylon thread, which is not all that strong. you must have done a really good stitching job. the woman at the sewing shop probably gave you a rounded point needle. I have just been using a universal needle, a rounded point would probably be better. I have sewed a few more slings (and loops at the ends of webbing) and use them when top roping, which puts little stress on them. I always show the other climbers what I am doing and give them the chance to opt out. But they are always comfortable with the slings, they know I am a crazy engineer.


dynosore


Jul 30, 2012, 8:33 AM
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splish wrote:
Rudmin wrote:
spikeddem wrote:
Gthomann, you keep saying the forces in a TR setup aren't much. I'm curious about the numbers you have for that. What forces have you observed?

I'd also be a bit surprised if it took a thousand pounds of force to lift the tail of a truck off the ground. Maybe if it was a pretty big truck with entirely too much junk in its trunk.

That truck probably weighs around 5000 lbs. If the centre of gravity was halfway between the front wheel and the hitch, he would be pulling up 2500 lbs. Since it's probably forward of that, 1000 lbs sounds like a very reasonable conservative estimate.

I have a full size SUV, with straight axles, and it doesn't weight 5000 lbs. The weight of any vehicle is on the door. The truck has no weight in the back. In high school, me and 3 other guys used to lift the back of Jeff's truck off the ground and turn it sideways in the parking spot. The back of a truck is ridiculously light!!!
Lift the engine, then I will be impressed. But I don't understand why this guy doesn't test it the same way UIAA does, put a wieght on it and drop it! find a porch or balcony or something. And a sand bag or some dumb bell weights!

Again, a full size pickup has a weight distribution around 55/45 front/rear, depending on box length, 2wd or 4wd, etc. Three of you picked up 2000 lbs or more?

What "full size" SUV do you have that weighs less than 5k pounds? A Tahoe, Suburban, or Expedition weighs between 5200-6500 lbs depending on the model. What do you drive?


billcoe_


Jul 30, 2012, 1:04 PM
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jt512 wrote:
The problem is, as research has shown, people who don't know what they are doing, don't know that they don't know what they are doing.

Jay


This is the only thing any of us really needs to read here, and it should be required reading. When teaching others climbing skills, I always emphasize repeatedly that they will not be aware of the things they don't know, and that lack of knowledge will and does often lead to a tragedy that totally blind sides them. 5 star link and post Jay.


splish


Jul 30, 2012, 6:44 PM
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dynosore wrote:
splish wrote:
Rudmin wrote:
spikeddem wrote:
Gthomann, you keep saying the forces in a TR setup aren't much. I'm curious about the numbers you have for that. What forces have you observed?

I'd also be a bit surprised if it took a thousand pounds of force to lift the tail of a truck off the ground. Maybe if it was a pretty big truck with entirely too much junk in its trunk.

That truck probably weighs around 5000 lbs. If the centre of gravity was halfway between the front wheel and the hitch, he would be pulling up 2500 lbs. Since it's probably forward of that, 1000 lbs sounds like a very reasonable conservative estimate.

I have a full size SUV, with straight axles, and it doesn't weight 5000 lbs. The weight of any vehicle is on the door. The truck has no weight in the back. In high school, me and 3 other guys used to lift the back of Jeff's truck off the ground and turn it sideways in the parking spot. The back of a truck is ridiculously light!!!
Lift the engine, then I will be impressed. But I don't understand why this guy doesn't test it the same way UIAA does, put a wieght on it and drop it! find a porch or balcony or something. And a sand bag or some dumb bell weights!

Again, a full size pickup has a weight distribution around 55/45 front/rear, depending on box length, 2wd or 4wd, etc. Three of you picked up 2000 lbs or more?

What "full size" SUV do you have that weighs less than 5k pounds? A Tahoe, Suburban, or Expedition weighs between 5200-6500 lbs depending on the model. What do you drive?

I have a 2004 Nissan Pathfinder Chinook. Added equipment includes 8' of 1/4" steel skid plates, ARB Winch Mount 1/4" steel bumper, snorkel assembly, dual battery, various off road lights and a winch. Lat time I went through a scale, it weighed in a 2404 KG. And that is with 2 full grown adults sitting inside. Just over 5000 Lbs, so the stock Pathy weighs much less I assure you.
I just looked up a few dodge trucks on Google, and they all do weight over 5000 lbs, but in the back end the only weight is the box, the back half of the frame, the drive shaft and the rear axle assembly. I am not sure of the exact weight distribution, But I wouldn't think it to be the the 55/45 that you stated, I think it would be much less.
As for the truck we used to life in high school, it was a 1983 GMC S15, which is smaller than the current Canyon. A very small truck, and the back end was incredibly light. We would kind of bounce it until the tires left the ground, and move it a few inches at a time until we turned it sideways across 2 parking spots with a car immediately in front and behind so he could not leave until those cars were gone.
My point is, lifting the rear end of a truck off the ground with a sling proves little when it comes to the forces involved in climbing.
Also, looking at the photo of the lifted truck. They used a small hand operated hydraulic crane rated to 4000 lbs and the boom is not showing any signs of deflection. Having used these devices many times, I can tell you, when you lift close to the rated weight of the device, there is at least an inch and a half or more of deflection in the boom.
Also, if you click on the photo and blow it up to full size, you can clearly see that only one rear tire is approx. 3" off the ground while the driver side tire is still firmly planted on the concrete. The chain that they used to wrap the bumper and lift from looks to be a much smaller size as well, not rated for heavy lifting. Much smaller than tow chains. This is really not a very impressive lift, nor do I think that this experiment would prove his stitching to be climbing worthy.


(This post was edited by splish on Jul 30, 2012, 6:53 PM)


vinnie83


Jul 31, 2012, 10:09 PM
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gthomann wrote:
nylon thread, which is not all that strong

I've got to ask, what are you using that is so superior to nylon and just how strong is it?

I was under the impression that nylon bonded thread is pretty much the standard when sewing just about any safety related gear out of nylon, but maybe that's just how things were done at the place I used to sew harnesses.

In reply to:
I am a crazy engineer.

You maybe crazy, but you're definitely not an engineer.


splish


Aug 1, 2012, 8:30 PM
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gthomann wrote:
Thats really impressive, especially with nylon thread, which is not all that strong. you must have done a really good stitching job. the woman at the sewing shop probably gave you a rounded point needle. I have just been using a universal needle, a rounded point would probably be better. I have sewed a few more slings (and loops at the ends of webbing) and use them when top roping, which puts little stress on them. I always show the other climbers what I am doing and give them the chance to opt out. But they are always comfortable with the slings, they know I am a crazy engineer.

Ok, listen to me, and listen very carefully!!!
You keep insisting there is little force on a top rope anchor. This is simply not true.
Just close your eyes and imagine this scenario.
Your climber is climbing at a decent pace. It's a simple 5.7. You get distracted for a single moment, someone talks to you, or tries to point out another climb. You don't pull in all the slack right away, and the climber has moved up 3 feet. Just as you are turning back to spot your climber, he/she fall. 3 feet of slack in the system, she falls a total of 3 feet, plus you get lifted slightly off the ground, a 5' fall plus the combined weight of yourself and the climber. How are your slings going to hold up then? Are you really willing to risk your climbers life on it?
On top of it all, reading this post is very scary. You really have no concept of climbing forces and such, which tells me you really have no concept of how to set up anchors and such.
I very highly suggest you take a top rope anchor course and speak to some professionals about your slings. Please, this is not something to take lightly!!!


jt512


Aug 1, 2012, 9:19 PM
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JimTitt wrote:
I just thought I ought to correct you for the benefit of future readers in 2020.

This post is genius.


curt


Aug 2, 2012, 8:14 AM
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splish wrote:
gthomann wrote:
Thats really impressive, especially with nylon thread, which is not all that strong. you must have done a really good stitching job. the woman at the sewing shop probably gave you a rounded point needle. I have just been using a universal needle, a rounded point would probably be better. I have sewed a few more slings (and loops at the ends of webbing) and use them when top roping, which puts little stress on them. I always show the other climbers what I am doing and give them the chance to opt out. But they are always comfortable with the slings, they know I am a crazy engineer.

Ok, listen to me, and listen very carefully!!!
You keep insisting there is little force on a top rope anchor. This is simply not true.
Just close your eyes and imagine this scenario.
Your climber is climbing at a decent pace. It's a simple 5.7. You get distracted for a single moment, someone talks to you, or tries to point out another climb. You don't pull in all the slack right away, and the climber has moved up 3 feet. Just as you are turning back to spot your climber, he/she fall. 3 feet of slack in the system, she falls a total of 3 feet, plus you get lifted slightly off the ground, a 5' fall plus the combined weight of yourself and the climber. How are your slings going to hold up then? Are you really willing to risk your climbers life on it?
On top of it all, reading this post is very scary. You really have no concept of climbing forces and such, which tells me you really have no concept of how to set up anchors and such.
I very highly suggest you take a top rope anchor course and speak to some professionals about your slings. Please, this is not something to take lightly!!!

You should probably give your scenario a little more thought. It's impossible to generate a FF=1 fall top roping and your scenario would likely be far less severe. Let's assume a 50ft climb is being top roped. That means there is initially 100ft of rope running from the climber up to the anchor and back down to the belayer. Suppose the climber gets half way to the anchor (he's 25 feet up) and then falls, with the 3 feet of slack you mention. The resulting fall is only FF=.04.

Curt


Partner cracklover


Aug 2, 2012, 9:21 AM
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curt wrote:
splish wrote:
gthomann wrote:
Thats really impressive, especially with nylon thread, which is not all that strong. you must have done a really good stitching job. the woman at the sewing shop probably gave you a rounded point needle. I have just been using a universal needle, a rounded point would probably be better. I have sewed a few more slings (and loops at the ends of webbing) and use them when top roping, which puts little stress on them. I always show the other climbers what I am doing and give them the chance to opt out. But they are always comfortable with the slings, they know I am a crazy engineer.

Ok, listen to me, and listen very carefully!!!
You keep insisting there is little force on a top rope anchor. This is simply not true.
Just close your eyes and imagine this scenario.
Your climber is climbing at a decent pace. It's a simple 5.7. You get distracted for a single moment, someone talks to you, or tries to point out another climb. You don't pull in all the slack right away, and the climber has moved up 3 feet. Just as you are turning back to spot your climber, he/she fall. 3 feet of slack in the system, she falls a total of 3 feet, plus you get lifted slightly off the ground, a 5' fall plus the combined weight of yourself and the climber. How are your slings going to hold up then? Are you really willing to risk your climbers life on it?
On top of it all, reading this post is very scary. You really have no concept of climbing forces and such, which tells me you really have no concept of how to set up anchors and such.
I very highly suggest you take a top rope anchor course and speak to some professionals about your slings. Please, this is not something to take lightly!!!

You should probably give your scenario a little more thought. It's impossible to generate a FF=1 fall top roping and your scenario would likely be far less severe. Let's assume a 50ft climb is being top roped. That means there is initially 100ft of rope running from the climber up to the anchor and back down to the belayer. Suppose the climber gets half way to the anchor (he's 25 feet up) and then falls, with the 3 feet of slack you mention. The resulting fall is only FF=.04.

Curt

Don't shut him down, Curt, or he'll leave this one and find another five year old thread to resurrect so he can spew half-baked verbal diarrhea all over that too.

Sorry, splish, do go on. I believe you were sharing something brilliant and revolutionary?

GO


crasic


Aug 2, 2012, 10:33 AM
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curt wrote:
You should probably give your scenario a little more thought. It's impossible to generate a FF=1 fall top roping and your scenario would likely be far less severe. Let's assume a 50ft climb is being top roped. That means there is initially 100ft of rope running from the climber up to the anchor and back down to the belayer. Suppose the climber gets half way to the anchor (he's 25 feet up) and then falls, with the 3 feet of slack you mention. The resulting fall is only FF=.04.

Curt


Worst case scenario fall, where the belayer is asleep and takes in no slack and climber falls from the very top (assuming they can fall past the belayer without decking) is a factor 0.5, best case scenario (take and rest) is a factor 0, all top-rope falls are between the two.

When you calculate the fall impact load factor (F/W) for a 50ft climb, this corresponds to a range between 2.0 and 6.0. Which is then, at the extreme, doubled at the anchor (in the implausible scenario of it being an ideal pulley instead of a biner up top), in reality its more like 1.5x at the anchor due to biner friction.

So the worst case possible fall possible on top rope (again, almost impossible, a full route length worth of slack), will load the anchor 9x the weight of the climber, so around 1600lb (7KN) for a 180lb climber. Thats nothing to scoff at, but thats better than a fall from a short leader runout. And that is not including rope slip and a myriad of other factors that lengthen the fall and reduce the actual force on the anchor, His flying belayer will actually reduce the impact on the anchor then if he was anchored to an immovable boulder.

Slish's factor 0.04 fall will, in all actuality generate a fall impact factor of ~2.2, so approximated a 3-4x impact on the anchor. Meaning 600-800lb (3-4KN). Depending on your POV, thats either really small (in relative climbing terms) or pretty big (in absolute terms for home-stitched soft-goods), however its not at all bigger than that seen by a factor 0 fall, and the marginal difference between a factor 0 and 0.04 fall can be completely hidden by natural variations in friction at the top biner (e.g. a 0.04 fall on a more sticky or rough section of rope will generate less force than a FF0 fall on a section thats been glazed from a fast rappel)


curt


Aug 2, 2012, 11:30 AM
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crasic wrote:
curt wrote:
You should probably give your scenario a little more thought. It's impossible to generate a FF=1 fall top roping and your scenario would likely be far less severe. Let's assume a 50ft climb is being top roped. That means there is initially 100ft of rope running from the climber up to the anchor and back down to the belayer. Suppose the climber gets half way to the anchor (he's 25 feet up) and then falls, with the 3 feet of slack you mention. The resulting fall is only FF=.04.

Curt


Slish's factor 0.04 fall will, in all actuality generate a fall impact factor of ~2.2, so approximated a 3-4x impact on the anchor. Meaning 600-800lb (3-4KN). Depending on your POV, thats either really small (in relative climbing terms) or pretty big (in absolute terms for home-stitched soft-goods)...

That's probably a reasonable estimate. In any event, based on the ad hoc testing by wivanoff and splish himself on their own home-sewn slings and the data presented here:

http://www.caves.org/...ical/nhback/NH03.pdf

I probably wouldn't be too worried about using similar slings in a top rope anchor--particularly because I wouldn't construct the anchor to rely on a single sling anyway.

Curt


JimTitt


Aug 2, 2012, 11:58 AM
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jt512 wrote:
JimTitt wrote:
I just thought I ought to correct you for the benefit of future readers in 2020.

This post is genius.

Well thanks, nice to be appreciated!


wivanoff


Aug 2, 2012, 12:25 PM
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curt wrote:

That's probably a reasonable estimate. In any event, based on the ad hoc testing by wivanoff and splish himself on their own home-sewn slings and the data presented here:

http://www.caves.org/...ical/nhback/NH03.pdf

I probably wouldn't be too worried about using similar slings in a top rope anchor--particularly because I wouldn't construct the anchor to rely on a single sling anyway.

Curt

I've taken lead falls on those sewn slings I made. No apparent damage to the stitching <shrug>

BTW, an engineer friend saw the broken carabiner on my car floor one day. He asked if he could have one half. A few weeks later he hands me back a report, along with photo-micrographs, done by a test lab at the well known aircraft engine manufacturing plant where he worked at then time. Basically, the 'biner was made of 7075 aluminum and failed due to excessive loading after plastic deformation. There was no evidence of microfractures or any manufacturing defect. It broke from being loaded beyond what it was designed for.

Doesn't really matter. As I said, I stopped sewing slings a long time ago when sewn climbing slings became readily available. Was no longer worth my time or energy.

Disclaimer: And, at this point, I do not recommend that others sew their own climbing slings.


splish


Aug 2, 2012, 5:38 PM
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wivanoff wrote:
curt wrote:

That's probably a reasonable estimate. In any event, based on the ad hoc testing by wivanoff and splish himself on their own home-sewn slings and the data presented here:

http://www.caves.org/...ical/nhback/NH03.pdf

I probably wouldn't be too worried about using similar slings in a top rope anchor--particularly because I wouldn't construct the anchor to rely on a single sling anyway.

Curt

I've taken lead falls on those sewn slings I made. No apparent damage to the stitching <shrug>

BTW, an engineer friend saw the broken carabiner on my car floor one day. He asked if he could have one half. A few weeks later he hands me back a report, along with photo-micrographs, done by a test lab at the well known aircraft engine manufacturing plant where he worked at then time. Basically, the 'biner was made of 7075 aluminum and failed due to excessive loading after plastic deformation. There was no evidence of microfractures or any manufacturing defect. It broke from being loaded beyond what it was designed for.

Doesn't really matter. As I said, I stopped sewing slings a long time ago when sewn climbing slings became readily available. Was no longer worth my time or energy.

Disclaimer: And, at this point, I do not recommend that others sew their own climbing slings.

I was watching "How It's Made" on Discovery Channel the other day, and they had carabiners on there. I always thought they were made strictly of aluminum, but apparently currently, most manufacturers use an Aluminum / Zinc mixture. The zinc stiffens the biner.


wivanoff


Aug 3, 2012, 4:23 AM
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splish wrote:
I was watching "How It's Made" on Discovery Channel the other day, and they had carabiners on there. I always thought they were made strictly of aluminum, but apparently currently, most manufacturers use an Aluminum / Zinc mixture. The zinc stiffens the biner.

That's what I said Wink
"Basically, the 'biner was made of 7075 aluminum and failed ..."

Zinc is the primary alloying element in 7075. It's stronger and harder than the relatively soft 6061 - which has very little zinc. It's why softer cams made of 6061 seem to grip better.

This thread really has drifted. I think I'll let it rest now.


russwalling


Aug 14, 2012, 11:06 AM
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gthomann wrote:
Thats really impressive, especially with nylon thread, which is not all that strong. you must have done a really good stitching job. the woman at the sewing shop probably gave you a rounded point needle. I have just been using a universal needle, a rounded point would probably be better. I have sewed a few more slings (and loops at the ends of webbing) and use them when top roping, which puts little stress on them. I always show the other climbers what I am doing and give them the chance to opt out. But they are always comfortable with the slings, they know I am a crazy engineer.

Yer gonna die!!!!!!!!


MassiveD


Oct 30, 2012, 4:39 PM
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Yer not going to buy, anyway.

Back in the 70s we sewed a lot of stuff. I know a fair bit of what I sewed on my mother's Elna grasshopper was sewn with standard thread for sewing clothing projects. 40 years latter, still waiting for the die part.

Back then in Ontario, we were lucky to have an actual engineer who worked with the UIAA safety committee to learn from. I don't know that he knew much about sewing gear from that lens, but he sewed his own seat harnesses, and we all sewed a lot of gear. I'm still using some of that gear, the slings are prehistoric.

It is fascinating to learn that all you guys are climbing with load cells and certified riggers on every trad pitch, so you know for a fact all the numbers relating to your system. All we knew how to do was limit our exposure. Make educated guesses about our placements. It's cool to know you guys deal in a world of mechanical certainty. The progress is amazing.

I probably wouldn't sew a toprope runner, since knotting it is bomber, and i can't see any upside to sewing it. But I also don't feel to bad about my 1" slings, since best case the lighter ones in use today at 100% would be weaker than my slings with a big haircut.

When we made up harnesses, we built in redundancy so there was no way we were dying. But ultimately that meant a slightly less convenient harness, so that leads to commercial gear. And anyway, today, it is hard to come up with stuff that you can't buy a better commercial version of. It was easy to build stuff when the commercial version consisted of very basic swami, leg loop combinations made of only a few webbing sizes.


MassiveD


Nov 4, 2012, 1:20 PM
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One way to judge whether one should attempt a craft, particularly if it is currently industrialized, is to figure out how it was done by it's early practitioners. Some crafts like canoe manufacture have thousands of years of being made by regular non-engineers, but if the product originates in the industrial age it is conceivable that it requires special skills and training to make. One can break through this fog by observing how the product was made by those who might currently venture to tell you that you should not try to do it yourself.


Just finished reading this passage in the Don Whillans biography The Villain. It concerns Troll at the time Whillans approached them about making a harness for his Anapurna expedition. The famous Whillans sit harness. P259. Tony Howard Troll's director, and sole full time employee relates that at the time they were making their harnesses out of old mill belting sewn together by a local cobbler.


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