So I decided to make bands for my gun rather than buy to save a bit of money. I have a mares bandit 75cm gun, and I did the measurements on the stock band and it is way to long. So I cut 16mm bulk rubber to an average length for that length gun. The problem I'm having though is the bridle inserts for the dyneema wishbone came out when I tried loading the gun. I tied a constrictor knot on each side with some extra 1.9mm dyneema that I made the wishbone with. These were the inserts I used. https://www.amazon.com/gp/product/B00701REB0/?tag=deeperbcom-20 I'm just wondering if these are not that good of inserts or if there's something I may have missed in the process. Any help is appreciated.
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Problem with making bands
- Thread starterFreshwaterspearo
- Start date
Thread Status: Hello
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From the looks of them I don't see why the inserts wouldn't work, but it does say that they are for 1/2" pole spear rubber. Large ID band runbber has a 1/8" hole, and small ID rubber has a 1/16" hole. But on the other hand they should be too big rather than too small, and if you can get them into the hole, then they should stay as long as the constrictor knot is tight. Maybe you aren't pulling hard enough? Or maybe that line is not good for the purpose. I used waxed twine that is much thinner.
If you do need inserts, here are some nice stainless inserts for large ID rubber.
www.makospearguns.com
And here are the ones I use for small ID.
www.makospearguns.com
They're expensive, but they should last forever.
If you do need inserts, here are some nice stainless inserts for large ID rubber.
Stainless Steel Wishbone Inserts for standard 1/8" ID tubing
These stainless steel wishbone inserts for standard 1/8" ID tubing allow you to quickly change your wishbone cordage without having to retie your bands.
www.makospearguns.com
And here are the ones I use for small ID.
Q8 Stainless Steel Wishbone Inserts
These stainless steel wishbone inserts allow you to quickly change your wishbone cordage without having to retie your bands.
www.makospearguns.com
They're expensive, but they should last forever.
Maybe I'll try getting some thinner line, and maybe a dab of glue wouldn't hurt. I definitely check those inserts out for future bands. Thanks for the reply.
Correction on my original post I was using 2.2mm spectra cord. Not 1.9mm dyneema. Not sure if that changes anything.
2.2 mm cord for a constrictor knot would be extremely thick. That is more like for wishbones. I bet that is the problem. Look on the Mako site for the thinner stuff that they use.
I've never used it, but its looks close to the stuff I use. I alway put a drop of super glue on the constrictor knot.
Band Tying Line | MAKO Spearguns
Perfect for tying double constrictor knots when making your own power bands. Sold by the foot.
www.makospearguns.com
I've never used it, but its looks close to the stuff I use. I alway put a drop of super glue on the constrictor knot.
Just ordered some 1mm constrictor cord. The stuff that's made of woven kevlar. Will give it another shot when that comes in. Thanks for the reply.
Good luck. When you pull the thin stuff really tight it will looks like its going to cut the band but it won't. Just keep pulling as if you wanted to break it.
Got the constrictor cord in and got the wishbone on the band. Pulled it back by the wishbone and the bridles stayed in the band, so the change in cordage there helped. My problem now is figuring out the proper length. I thought I had it figured out doing the proper math but the band is way to short and very difficult to pull back to the first shark fin. Its 16mm bulk rubber with 1/8 id. My gun is a mares bandit 75. Doing the math with elongation being 250% put the length at 19.8in (50.29cm)
The equation I used is
L= band length
D=distance between band eye and closest fin or notch
Wbl=wish bone length
E= Elongation
L=((2D-WBL)/E)+1
Did I do the math wrong or is that equation off? I've looked on many different forums and sites for equations and this was the best that I could find that made sense to me right now as a beginner. Any help is appreciated.
The equation I used is
L= band length
D=distance between band eye and closest fin or notch
Wbl=wish bone length
E= Elongation
L=((2D-WBL)/E)+1
Did I do the math wrong or is that equation off? I've looked on many different forums and sites for equations and this was the best that I could find that made sense to me right now as a beginner. Any help is appreciated.
This is a chart from our website, but it is for 14.5 mm bands which are easier to pull and you MIGHT want to stretch a heavier band a little less. I ddin't check you math/formula, but this might serve as a somewhat independent reality check on your bands..
Speargun Band Length Chart for 14.5MM Diameter Bands
Speargun Band Length Chart for 14.5MM Diameter Bands
| Speargun Model | Length |
|---|---|
| 50cm | 13.66" |
| 60cm | 16.33" |
| 70cm | 19.00" |
| 80cm | 21.66" |
| 90cm | 24.33" |
| 100cm | 26.66" |
| 110cm | 29.66" |
| 120cm | 32.33" |
| 130cm | 35.00" |
| 140cm | 37.66" |