Knots Vs Knots, Joiners Vs Joiners

The Test Rig

Sometimes you know that a video is going to be controversial before you even start filming. This was one of them. 

A few weeks ago the boys at Spiralfast dropped off their test rig to me thinking I could use it in a video. Well, I got to scheming, roped in Steve Casamento and the project took shape. Over the course of a few hours, a BBQ and a bottle of wine one Friday night, Steve and I set up the rig in his factory and had fun breaking stuff. The plan was simple. Which knot is best, which joiners are the strongest? Well, it’s never that simple when you are talking about devices and knots people have invested themselves in for years is it?

Anyway, we did our best with the time and equipment at hand. It was a pretty simple test really. Each knot in turn and then each joiner in turn were strained at about the same speed until their breaking point, measured by a load cell. The plan was to see which ones cut the mustard. And have some fun. The results were pretty predictable really, in fact I was chuffed with the result, predicting the order almost exactly (I did put the Tex Brown over the Donald/Speed/Strainer knot…. But even that only came down to a few kilos).

There have been suggestions and requests following the video. Some good ones have included performing multiple replications (Will need more time, wine and BBQ), twisting the ends of the wire after the Gripple (even though this is not recommended and probably won’t make a single bit of difference as the Gripple fails when it cuts through the wire) and so on. So look out, if we can manage it, we might even do a follow up video….. And get more suggestions…..

So what were the results? Well, the table is below. Remember, this was not a scientific trial as there were no replications and can’t tell you the standard deviations or ANNOVA values. We did however use the exact same roll of wire for each test, set up the test rig identically for each trial and use new wire for each test. ALSO, you need to understand what “success” in this trial actually is…. Truth be told, anything that can go over 300Kg’s is probably pretty good in most stock fencing cases. So everything except the double loop will work fine (except don’t use the figure 8 with strainers…. It takes up as you release them and you lose tension). 

Having said this, there are some applications like trellis wires under tension from covers or vine trellis that’s machine harvested, where every bit of strength counts. There’s also something to be said for the two solutions that gave way without releasing the wire (the Donal Knot and the Spiralfast) as this will still keep the stock in and reduces the chance of injury to people around the fence if it lets go. Personally, I’ll always go with the strongest option, there’s nothing worse than wires stuck in your harvester or an angry call from a neighbor at 3am because some darned knot or joiner gave way….

At the end of the day, for some people it won’t matter what the results of this test were, their way will be best and the test must have been wrong for some reason. The good news from this trial is that for most applications, they are right. Everything but the double loop did it’s job as it was supposed to. So almost all of you (except the old angry guy down at the pub who has double loops in his fences) are correct. Isn’t that nice?

Thanks a whole lot to Spiralfast and Steve Casamento for the use of their equipment and facilities in the making of this video. Steve cooks a mean BBQ by the way…..

Results

DeviceBreaking / Slipping Strain (Kg)
2.5mm wire no join585
Double Loop260
Figure 8394
Tex Brown399
Donald (Speed) knot410
Gripple397
Crimp497
Spiralfast550 
This table shows the result for one time tests using the same wire reel with wire replaced with new wire for each test

See you next time over the fence somewhere.

Cheers, Tim.

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