Adhesive bonding lengths of fabric strapping

[GreensandsParticipant @greensands]

I wish to be able to bond together the two ends of a 25mm width, 1m length fabric strapping in order to make up a load bearing strap-loop for manhandling my model locomotive. Initial thoughts are along the lines of a) stitching (not easily arranged), riveting (as used for leather work) and finally possibly adhesive bonding.  Would the use of adhesives be suitable for this type of application and if so, which type of adhesive would be most suitable for the job?  The fabric strapping is rated at 205kg which is far in excess of the anticipated loads but may help to resolve the problem.  All suggestions most welcomed.

[GreensandsParticipant @greensands]

I should of course have made it clear that I would be looking for a lap jointed bond.

[Robert Atkinson 2Participant @robertatkinson2]

I would only consider adhesive bonding for this type of application if the bond length was  greater than 360 degrees. i.e. consider the loop as a roll of strap with at least two full turns. The entire contact area between the turns is bonded. A contact adhesive e.g. “Evo-Stick” would be a suitable choice.

If you want it machine stitched, have a look on the internet to see if there is a “repair cafe” near you these often provide sewing services at no cost but you can make a donation.

Robert.

[Michael GilliganParticipant @michaelgilligan61133]

I’m a big fan of adhesives, BUT this looks like a situation where stitching would be the more reliable option … Just have a look at your car seat-belt, or any item of military webbing.

MichaelG.

.

[ Peel-strength will be the problem. ]

[John HaineParticipant @johnhaine32865]

Rope, knots.

[Maurice TaylorParticipant @mauricetaylor82093]

Hi,
Would a length of car seat belt be long enough. Suitable fastener with bolt hole at one end ,needs similar fitting at other end

Maurice

[Nigel Graham 2Participant @nigelgraham2]

I would not even try it for an application like that. Apart from risking injury to yourself, you don’t want to risk dropping the locomotive by a home-made sling failing.

Buy proper webbing “round slings”, sold as lifting-gear or “garage equipment” by some of the major tool-stockists as well as specialist lifting-gear dealers; and they are not very expensive.

Oh – and use them correctly, which includes not tying knots in them.

[Nick WheelerParticipant @nickwheeler]

properly sewn, certified nylon slings are so cheap that attempting to glue your own can’t be worth trying. They are cheap because industry considers them disposable.

[peak4Participant @peak4]

Personally, I’d visit the local rock climbing shop.
They will have a variety of pre-sewn tape slings, or will likely have some tape by the metre, possibly tubular, and show you the best knot to use; essentially a simple thumb/overhand knot

Bill

 

 

[DC31kParticipant @dc31k]

Can you find one example in the real world, from any field of application, through any period in history that uses a bonded method?

If you find 200 examples of looped slings, how many varieties of joining method do you see?

That statistical analysis might tell you something about your proposal.

The stitching is called ‘box stitching’ It is used a lot in sailing as well as climbing and there are formulas and best practice guides available which can guide you.

This video is a starting point. There is a printed document somewhere which captures essentially the same information.

https://www.sailrite.com/How-to-Sew-Webbing-Loops

A needle, thread, and thimble is all the equipment you need to arrange; the stitching does not have to be done by a machine.

A neat alternative might be a synthetic braided rope (dyneema) made into an endless loop. Again, there are tutorials on this from the sailing world. In effect, you create a Chinese finger trap. You just have to be mindful that the bury length for the spices is something like 45-50 times the diameter so for a 1m finished loop, 6mm or 8mm rope would be goos sizes to pick.

[Bo’sunParticipant @bosun58570]

Good morning Greensands,

Commercially made (& rated) endless slings are probably the way to go, but maybe considered OTT for what you’re doing, depending on the weight of your loco.

peak4’s suggestion is sound and relatively inexpensive if you tie your own sling.  If I remember correctly, the knot you need is called a “water knot”, and is essentially an overhand knot re-threaded in reverse.  Very easy, and plenty of YT videos to show you how.

[Nigel Graham 2]

On Nigel Graham 2 Said:

 

Oh – and use them correctly, which includes not tying knots in them.

Hi Nigel Graham 2, What !!!

Good job I only use this one for pulling my low flat four wheel barrow then.

But yes use them correctly, and if they are on corners, use some soft packing to prevent damage to them, like what can be seen at the top left, in the first picture.

Regards Nick.

[SillyOldDufferModerator @sillyoldduffer]

Nigel is right about knots:  they all reduce the strength of the rope, some of them dramatically!   Splices are best.

Greensand’s strap is rated at 205kg and joining the ends with a reef knot reduces that to about 100kg.   Start worrying because a reef knot is more secure than glue.

Adhesives are only effective when used appropriately, and that doesn’t include joining the ends of load bearing straps!  MichaelG pointed out adhesives have low peel strength, so any situation that applies sideways force or puts a stress raiser on an edge will quickly destroy a glued joint.

Stitching, riveting, and splicing are all much safer if you must.   I’d take Nigel’s advice about buying the right thing though – DIY is unnecessarily risky.

Dave

[John HaineParticipant @johnhaine32865]

The reason I suggested ropes and knots is because for example a bowline in a reasonable diameter rope will easily hold the forces from a moored boat.  Sailors have spent centuries developing knots that hold strongly and don’t excessively weaken the ropes they are tied in.  Mountaineers trust their lives to knots on safety ropes.  Why ignore all that practical experience?

[Neil AParticipant @neila]

As others have said, joining fabric strapping with adhesive is not a proven method of producing lifting gear.

When I lifted my lathe, only 60Kg, into position by myself I used a 1000Kg sling from Screwfix and a 500KG lever hoist. Overkill I know, but better than having something fall.

Your locomotive is a valuable item, best to used tried and tested means of lifting.

Rope, spliced or knotted. Peak4’s climbing slings, I see some are rated as 22Kn breaking strain. Or just buy suitable equipment.

Lifting is always considered as a safety critical operation, don’t take any chances.

Neil

[Pete.Participant @pete-2]

As pointed out,  you can buy lifting straps so cheap it’s not even worth buying adhesive or the petrol to go looking in shop, £7 gets you a 1 ton rated strap delivered to your door.

[Nick WheelerParticipant @nickwheeler]

Neil has covered everything I would.

 

The OP mentioned 25mm strapping to make his slings, so I Googled that and got this LINK. That gives a 1.2m long, 25mm wide sling rated to 30kN for £6.88. It cannot be worth making your own and testing them to your satisfaction for that much.

One thing nobody has yet mentioned is how and what the sling is going to be attached to. Having had a winch hook go flying past my head because I used a sling instead of chain on a sharp metal crossmember, I would be considering some nice smooth shackles. Although a couple of cheap, 1 ton rated 25mm ratchet straps would easily do the required job….

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, ratchet straps should never be used for lifting, as they are not designed for it, insurance companies in all likely hood, will not pay out for accident by using them for lifting, and if someone was to get injured or even killed, you may well find yourself in lot of trouble. They are for restraining things on trailers and maybe roof racks, and in vans and the like.

Regards Nick.

[DC31kParticipant @dc31k]

There appears to be some reading comprehension difficulties among those providing links to bought items.

Please read the original post very well; “I wish to be able to bond together the two ends of a 25mm width, 1m length fabric strapping in order to make up a load bearing strap-loop”.

Joining the two ends of a 1m long piece of material will produce a strap with a working length of 0.5m so the £7 one is irrelevant.

If anyone is to go searching in an attempt to assist, please at least have the good sense to search for what is actually being asked for.

[Pete.Participant @pete-2]

<p style=”text-align: center;”>Plenty of listing’s with drop down menus to choose the length needed, style etc, please have the good sense to understand nothing was linked,  an example was shown.</p>
 

[duncan webster 1Participant @duncanwebster1]

A reef knot can easily turn into a slip knot. If the OP wants to use a knot then climbers would use a tape knot otherwise known as a water knot.

The webbing is rated at 205 kg, but making it into a sling doubles this, so losing 50% with a knot gets you back to where you started. We don’t know how much the OPs loco weighs, an average 5″ g loco is 65 kg of so. I just use 6mm blue rope, breaking strain in over 500 kg, anx I have a loop both ends so plenty in reserve

If OP wants to sew webbing then find a saddler.

[Bo’sunParticipant @bosun58570]

Agree with Duncan about using the Water Knot as I posted earlier.  If you go this route, make sure the tape lays correctly when re-threading, leaving about 100mm tails before setting the knot.  Apply stopper knots or sew the tails to the loop for added security.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi DC31k, Belt Lifting Slings Top one in the drop down box, does seem to give the width at 30mm for purple ones though.

Regards Nick.

[Nigel Graham 2Participant @nigelgraham2]

DC31k –

No-one was mis-reading the question!

Plenty understood him and were advising against his idea of trying to glue tape webbing to make slings. No lifting-sling is ever made by gluing, for the simple reason that is just not reliable and safe!

Knotting flat webbing is OK but you do need use the proper knot for it. You never tie knots in webbing slings to shorten or join them.

A knot in a rope is weaker than the parent rope – a rough but fair rule-of-thumb is half the breaking-strain. Still, you can use knotted-rope slings provided you use an appropriate knot and rope so the sling has the required strength including safety-factor. The Figure-of-eight loop is perhaps the least weakening, hence its use by cavers and climbers; but omitted from the list above.

Splices are stronger, for the same rope, but more difficult to make than knots and not all ropes can be spliced. Books on splicing, and ropes, are available from, e.g. yacht chandlers.

I have made short single-slings in hawser-laid rope, with an eye-splice at each end, for lifting relatively light but awkward items in my workshop. I do though also have a selection of commercial round-slings, shackles and eye-bolts for more serious lifting.

 

When you have operated over-head cranes professionally, had to use a lot of ingenuity to re-erect your workshop machinery after a house move, and have oft-times dangled on rope high above the floor of a cave shaft, you tend to gain some respect for lifting-gear, slings and rope methods and safety…  It ain’t worth gambling with them!

[Bo’sunParticipant @bosun58570]

Good morning Nigel & Dave.  Just curious, but why does a knot weaken the strength of the parent rope?

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