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 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.

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.

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.

Russ?

You trolling us?

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

I would say he is "already dead".

(T1- at best)

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

I would say he is "already dead".

(T1- at best)

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

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.

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.

Great job! I'm impressed. The money you've saved over purchasing pre-made slings should more than cover the cost of your funeral.

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.

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.


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

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)

I saw a guy try to use homemade
slings designed just like yours...

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

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

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.

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.

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

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

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.

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.

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

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

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.

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.

Not sure how comfortable you are doing a little math . . .

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.

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.

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

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.

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.

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.

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!

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.

.

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.

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!!

Perhaps gunkiemike was making fun at your expense as the UIAA do not drop-test slings.

Lift the engine, then I will be impressed.

I just thought I ought to correct you for the benefit of future readers in 2020.

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

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!

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

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?

nylon thread, which is not all that strong

I am a crazy engineer.

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.

I just thought I ought to correct you for the benefit of future readers in 2020.

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

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)...

This post is genius.

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.

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.