Strength (Tensile?) testing webbing things I've made

[Beanwood]

Dear collective

In my spare time, I make dog collars and leads. I'm pretty good, and hope to start selling them soon, but being largely risk averse, I'd like to prove to myself the various combinations I'm using (Riverts/stitching/steel/stainless steel/rope/webbing/welded O etc. will be 'up to scratch', and if they aren't, change the design/materials accordingly.

It struck me as being similar to web sling testing - but at much reduced loads (These are roughly 400kg rated, which is a fairly big dog aking off at a rate of knts from a standing start....)
I don't have loads of money to invest in this, but I need to be sure it's right. Can anyone suggest either a repeatable method I can use that will give me accurate(ish) results without a £2k capital purchase, or a company I can phone to ask about the service they may provide?

Ta.

 

[Shiny Steve]

There's a company in N Wales called dmm they make rock climbing gear. They have always been very approachable.

 

[Agroshield]

A digital crane scale (e.g. https://www.fruugo.co.uk/500kg-hanging-crane-scale-digital-lcd-display/p-113074329-238324878 ) would show the force applied.

Put on the load with a standard chainblock or lever hoist.

Resisting the load is a difficulty. If you have a length of I-beam in the back yard, you are halfway there.

The biggest challenge with an affordable scale is that it will not have a 'peak hold' function, but you can film the display with your phone. Film the item being tested with another phone so you can replay the failure mode.

For some ideas, have a look at HowNOT2 on Youtube.

You will soon see that the breaking strength of anything you make is highly dependent on the restraint conditions at the two ends. So, for example, if one end of the lead would be held in a human hand, the pin it goes around on the testing rig needs to be similar in size.

If you send your things off to a third party, amongst other things, you will need to specify how the two ends are to be held and the rate at which the load is applied. At the end of it, you would get back the broken item and a piece of paper with the load written on it. Seeing it or filming it while it goes from zero to snapped will tell you a great deal and this aspect might not be part of the standard service.

 

[hotponyshoes]

If it's just for your own reassurance then something simple like a step ladder and a plastic tub would be ok.
Fill the tub with water using a 5l bottle until the lead snaps and you'll get a result to the nearest 5kg or so.

If you want to test each one just make up a leaver arrangement so you don't have to lift a heavy weight each time.

That would be enough to make a claim of "tested to an excess of 100kg" for example.

You could do the maths and work out just how much force a big dog can put on a lead if it suddenly jumps for something but I'm not sure that would be necessary?
I'd guess that, once a sample was proven, the care and condition that the owner keeps the lead in would probably be more relevant. Ie, if they crumple the lead up and stuff it in a pocket with a bunch of keys for most of the walk the stitching might get snagged easily.
Same as if they hang it up damp in a damp porch when they get back from the walk...

 

[Kram]

Here is the required watchings..

https://youtube.com/@HowNOT2

Its worth noting most things will give a very different value for slow pull or dynamic. The bend radius /knots significantly reduce strength.

A linescale3 would be the device to get, except for the €600 price!

I just bought a slackline and Im quite annoyed it has no proper ratings/markings to show that the webbing is fit for purpose. All proper climbing gear must have markings, possibly they get away with it using a max 0.5m height warning.
Particually because it came with a second skinnier webbing which I intend to use as a slackline, its only intended as a training line to balance your hands.
Theres quite a difference to the stiching between the two so I'll get sewing machine out and add some kevlar stiches on the skinny one sewn ends.

 

[Beanwood]

I knew you guys would come up trumps.

I think @Agroshield has it though with Crane Scales being the way to go. They're really cheap at £35 for 500kg, and I can hook it up to two tow bars, with chain blocks to do the pulling. Even if it's 10% out, it'll give me an indication.

Good point @hotponyshoes about the contact points - Whenever I've seen tests before, it's usually the stitching that goes - but if I can get my own rig set up for £40, I can test all sorts of combinations - including stitch patterns/threads, which really appeals.

@Kram you know there's a calculation you can use for stitch strength if you can assume a thread strength - you may not need to get that machine out:. Sailrite stitching

Once again - you've proved this forum knows everything!!

 

[Beanwood]

There's a company in N Wales called dmm they make rock climbing gear. They have always been very approachable.

Thanks @Shiny Steve - tried calling them this afternoon - but they must have all been out climbing! I've emailed them anyway.

 

[Robotstar5]

You could do the maths and work out just how much force a big dog can put on a lead if it suddenly jumps for something but I'm not sure that would be necessary?
I'd guess that, once a sample was proven, the care and condition that the owner keeps the lead in would probably be more relevant. Ie, if they crumple the lead up and stuff it in a pocket with a bunch of keys for most of the walk the stitching might get snagged easily.
Same as if they hang it up damp in a damp porch when they get back from the walk...

Our dog would have made a good lead tester when he was a puppy, if you stopped to look in a shop window or talk to someone for a couple of minutes, you look down and he's chewed most of the way through his lead

 

[Beanwood]

Our dog would have made a good lead tester when he was a puppy, if you stopped to look in a shop window or talk to someone for a couple of minutes, you look down and he's chewed most of the way through his lead

You sir, are my sort of customer - buy a lead, and two weeks later, after a few window shopping outings... buy another!!
Oooh - I think you've just become part of my retirement plan!

 

[Robotstar5]

You sir, are my sort of customer - buy a lead, and two weeks later, after a few window shopping outings... buy another!!
Oooh - I think you've just become part of my retirement plan!

2 weeks!, we bought a new lead to take him on holiday when he was 6 months old, by the middle of the week we were looking for a pet shop to buy another

We also tried the straps that are supposed to keep him on the back seat of the car, after he chewed through 4 of them we gave up.

Enjoying the field behind the holiday cottage

 

[skotl]

I find this interesting as I sometimes wonder about this when out with my 25KG lab/collie cross. He will often bolt while on the lead and I can tell you that kinetically (may not be the right word) it is a lot more than 25KG at the point the lead hits full extension. It's occurred to me that there's only some stitching and a couple of rivets that's stopped him running off into the road after some imagined or real foe.

So I don't know if it's as simple as using a strain or static load - for me it would need to be that kinetic snap that would should be measured.

 

[hotponyshoes]

I find this interesting as I sometimes wonder about this when out with my 25KG lab/collie cross. He will often bolt while on the lead and I can tell you that kinetically (may not be the right word) it is a lot more than 25KG at the point the lead hits full extension. It's occurred to me that there's only some stitching and a couple of rivets that's stopped him running off into the road after some imagined or real foe.

So I don't know if it's as simple as using a strain or static load - for me it would need to be that kinetic snap that would should be measured.

You could do the maths to work out the "snap" or measure it somehow or the information may already be available somewhere.
If a 25kg dog can produce a 75kg shock load then a static test at 100kg would be fine.
But, I would expect a dog lunging against a lead to cause problems over time rather than instantly.

Unless the dog is tied to something solid the human is going to flex a fair bit and absorb some of the shock for a start.

Then, if yanked, a rivit might well have more than enough strength to hold but it will dig into the leather/fabric slightly. Same with the stitching. It will gradually chew through and work loose over time.
I'd guess 100x 30kg shocks would cause a lot more wear than 1x 100kg shock?
Same with the lead getting wet.
I can see the lead expanding when it gets wet causing stiches/rivits to dig in slightly.

I don't know if there is any sort of standard for testing dog leads, maybe looking at some other manafactures websites would tell you if they make any claims for theirs?

 

[GRW]

If you consider a biggish human at say 100kg... then that this 100kg is stationary....
Then wouldn't a good test be to drop a weight equivalent to the weight of a dog the lead was designed for (say a 30kg Pooch).....
Secure the Human end to a Beam, then drop that 30kg over the full length of the lead?
If it doesn't break - then it'll be strong enough to arrest Fido mid-take-off?
(The longer the lead, the more force of mass accelerating it'll have to withstand).

Bear in mind also that the anchor point for the test (mimicking the 100kg human)... Will be fixed and solid, where in reality the actual human will be pivoted around his feet and flat on his face long before your Test forces get applied to the Lead

 

[pedrobedro]

(These are roughly 400kg rated, which is a fairly big dog taking off at a rate of knots from a standing start....)

That's the weight of a grand piano, about 8 Rottweilers or a medium size horse. Anybody holding onto that lead is going to be flying.

 

[Gareth J]

I find this interesting as I sometimes wonder about this when out with my 25KG lab/collie cross. He will often bolt while on the lead and I can tell you that kinetically (may not be the right word) it is a lot more than 25KG at the point the lead hits full extension. It's occurred to me that there's only some stitching and a couple of rivets that's stopped him running off into the road after some imagined or real foe.

So I don't know if it's as simple as using a strain or static load - for me it would need to be that kinetic snap that would should be measured.

Dynamic loading. But kinetic works as well.

Get a big frame, a 30kg bit of steel and drop it from ~1m high. That'll accelerate it to ~4m/s (~10mph)

The equivalent of a big dog, accelerating quickly from a fairly short lead tied to a sturdy object.

Repeat as required to test long term reliability.

If you want to test for a huge dog stopping from 20+mph from the end of a very long, inflexible chain, numbers would start to get silly. But I suspect you might start getting into the limits of what forces a dogs neck can transmit pretty quickly!

 

[Beanwood]

2 weeks!, we bought a new lead to take him on holiday when he was 6 months old, by the middle of the week we were looking for a pet shop to buy another

We also tried the straps that are supposed to keep him on the back seat of the car, after he chewed through 4 of them we gave up.

I can attest to dog's teeth being very effective on safety belts. Cue labrador in the boot area of wife's 3 month old Kuga company car, with us stood outside for two minutes. He was very quiet.... That cost me mre than I care to remember...

I find this interesting as I sometimes wonder about this when out with my 25KG lab/collie cross. He will often bolt while on the lead and I can tell you that kinetically (may not be the right word) it is a lot more than 25KG at the point the lead hits full extension. It's occurred to me that there's only some stitching and a couple of rivets that's stopped him running off into the road after some imagined or real foe.

You're right - it is far more than 25kg - and why I want to be able to reassure people.

You could do the maths to work out the "snap" or measure it somehow or the information may already be available somewhere.
If a 25kg dog can produce a 75kg shock load then a static test at 100kg would be fine.
But, I would expect a dog lunging against a lead to cause problems over time rather than instantly.



I don't know if there is any sort of standard for testing dog leads, maybe looking at some other manafactures websites would tell you if they make any claims for theirs?

It's crazy - I can recall the class at college where I learned the equation I need. I remember the lecturer, the 'AC/DC' folder from the guy behind me - but can I recall that damned equation - can I heck!

That's the weight of a grand piano, about 8 Rottweilers or a medium size horse. Anybody holding onto that lead is going to be flying.

Yes - I reckon unless I've got a very strong 400kg customer, with a pack of Rottweilers on one lead, the lead is unlikely to be the weak point.

 

[DaveB]

If you decide to test using a chain block and some kind of crane scale then remember that all that equipment can be hired.

 

[Beanwood]

If you decide to test using a chain block and some kind of crane scale then remember that all that equipment can be hired.

Thanks - I'm lucky that I have all I need, except the crane scales - which seem inexpensive - although I doubt they're certified accrate for £34..

 

[PhillipM]

Your problem with a lot of this testing commentry/replies is people assuming someone is holding the lead.
A lot of people will tie a lead off to something solid when they need to leave a dog or secure them outside a shop, etc, in which case your shock loading just went up massively - as well as the knot in the lead adding a massive stress riser.
As someone else mentioned, fatigue over time from the cyclic loading and also dirt/dust wear from getting embedded in the leather or cloth might be something you want to look at depending how long you expect things to last too. Same for things getting wet or being used wet, etc.
It's the usual trick with testing - how far do you want to dig into it, as it can be a massive time sink.

 

[Migmac]

I find this interesting as I sometimes wonder about this when out with my 25KG lab/collie cross. He will often bolt while on the lead and I can tell you that kinetically (may not be the right word) it is a lot more than 25KG at the point the lead hits full extension. It's occurred to me that there's only some stitching and a couple of rivets that's stopped him running off into the road after some imagined or real foe.

So I don't know if it's as simple as using a strain or static load - for me it would need to be that kinetic snap that would should be measured.

My pet hate, dogs pulling on leads. I accept it whilst we’re tracking but not if we’re out for a walk. I spend a lot of time training my dogs to walk at heel on the lead or off.