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.

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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!!