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07-05-2018, 08:39 AM | #1 |
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Location: Stockholm, Sweden
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Band stretch. Where is the upper limit?
Where is the limit when band stretch starts to degrade performance?
I reused some old but good bands and had to cut a little. Previous band stretch was about 380%, and now it’s like 412% on the longer band and 419% on the shorter band. This is on a small 82cm gun with 14mm small ID rubbers and a 120cm 6,75mm shaft. |
07-05-2018, 10:34 AM | #2 |
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Re: Band stretch. Where is the upper limit?
When your eyeballs are popping out, it's just right!
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07-06-2018, 12:35 AM | #3 |
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Re: Band stretch. Where is the upper limit?
Does your trigger mechanism work OK under such load? What is the gun make?
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07-06-2018, 02:47 AM | #4 |
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Re: Band stretch. Where is the upper limit?
Well I guess it wound for long. Pathos. D’angelo 1 handle / trigger.
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07-06-2018, 06:02 AM | #5 |
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Join Date: Sep 2002
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Re: Band stretch. Where is the upper limit?
Primeline told me they recommend max stretch at 400%. Any more than that will cause significant damage to the tubing. For storage of latex tubing they recommend 70 degrees and 50% humidity.
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07-06-2018, 07:41 PM | #6 |
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Re: Band stretch. Where is the upper limit?
See if you can use one Primeline 14mm small ID band stretched to 360-370% on your Pathos. It works excellent on my Picasso Magnum 95. Good and consistent accuracy and penetration at 4 meters (5.6 meters from the eyes).
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07-07-2018, 07:50 AM | #7 |
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Re: Band stretch. Where is the upper limit?
I’m changing the old bands and going down in stretch. Had the wishbone inserts popping out a few times, I guess that alone is a good sign of the need for a little less stretch.
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07-08-2018, 03:48 AM | #8 |
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Re: Band stretch. Where is the upper limit?
I think about 390% is the very limit. That is when bands stop getting "stretchy". If you can load 15mm small ID bands to 390% ... you certainly have got your band loading technique optimized!
As for wishbone inserts popping out, this should never happen even with large ID bands and much higher load than 400% stretch. What line are you using to tie your constrictor knot? Best is to use line with no slippage or stretch ... such as Kevlar or Technora. If you use spectra or other line that slips, your knot will loosen and an insert can pop out. |
07-08-2018, 07:06 AM | #9 |
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Re: Band stretch. Where is the upper limit?
I’ve been using the Mako band tying line. Super rigid and unstretchy. I’ve changed out the bands and am now at 380% and I’ve been meticulous tying the bands and had no inserts popping out since.
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07-09-2018, 08:22 AM | #10 | |
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Re: Band stretch. Where is the upper limit?
Quote:
I have a Picasso Cobra Rail 100cm with 6,25mm shaft (130 or 140cm long, I can't remember) and I use 17mm primeline (small ID). Smaller guns, such as a frankengun I put together for dirty water or holes (keep in mind I don't shoot big fish) is 82cm long, 6,25mm x 115cm shaft and has a 16mm small ID band. Again, 14mm single band... meh.... |
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07-14-2018, 07:06 AM | #11 |
the deeper the blue.....
Join Date: Oct 2016
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Re: Band stretch. Where is the upper limit?
have to disagree with Majd on this one. Am super happy with my Primeline small ID bands tied at 400%, both Spearitco's black 14.4mm and Benthic's grey 14.8mm, the latter which I'm now using on all my guns from 100cm bandstretch single-band reef gun all the way up to 146cm stretch three-band Albacore shape
Granted, all my shafts have loading tab at 36cm from the tail, which for me is a totally worthwhile tradeoff in being able to swim around with so much power in such a compact, streamlined package. You've got to breathe up between dives anyway, and with practice the two-stage hip-to-gut load is pretty damn effortless at 420% and beyond yes, the rubber dies pretty quick, and you get the occasional bridle insert pop even using good SS inserts and kevlar constrictor cord. but 400% really is the sweet spot for me, lots more pop than tying at 370-380. Allows me to consistently penetrate solid fish even with single band at the 4 metre range a single wrap allows on 124cm bandstretch gun, and thats with 140 x 7mm heavy duty Hunt TIG'd flopper shaft after one cut-and-retie I transition band down to progressively shorter guns, so still getting moneys worth from that [very] expensive US-sourced rubber Last edited by kavachi; 07-14-2018 at 08:03 AM. |
07-14-2018, 08:07 AM | #12 | |
the deeper the blue.....
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Re: Band stretch. Where is the upper limit?
Quote:
Shaft is Hunt 7mm x 140cm with ultra heavy duty TIG'd flopper and cone - weighs in at 430 grams pushing all that stainless is a SINGLE 62cm band of ~14.4mm small ID black Primeline from Spearitco, tied at 400%. very short bridle. shaft loading tab at 36cm from tail makes loading super easy, and I'm not Cameron Kirkconnell or KY Tony I am consistently taking decent fish [small doggies, armor-skinned white surgeons 5kg, solid spanish and cuda] with this shaft at 4 metres range [single wrap on 124cm bandstretch railgun] No, this rig isnt going to go thru a big tuna. or penetrate a hoo at 5+ metres, but its deadly efficient on most dinner species that swim past, and soooooo quick and easy to reload all day long, esp when a suicidally curious mack is swimming round under your fins and needless to say being a 145cm loading-pad-to-speartip single band aly railgun, its pretty damn light and manouverable Hoping to get round to finally buying some ~15.7mm small ID primeline and testing out on 150 x 7.5mm Hunt shaft, seeing just how far can take the optimised single band shooter Last edited by kavachi; 07-14-2018 at 03:19 PM. |
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07-15-2018, 05:55 PM | #13 | |
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Re: Band stretch. Where is the upper limit?
Quote:
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07-21-2018, 02:04 AM | #14 |
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Re: Band stretch. Where is the upper limit?
Agreed with HurricaneBK. My Picasso Magnum 95 came with the single 17.5mm rubber cut at 330%. It was not too hard to stretch, but not too easy. So I decided to replace it with the single 16mm regular ID Primeline rubber, which I had lying around, stretched at 350%. Replaced Picasso Gold 140x6.5 shaft with Sigalsub 130x6.75 with the cone. Target shot the gun and it produced good accuracy and penetration through 3" construction styrofoam at 4 meters from the tip. Then I decided to try 14mm small ID Primeline rubber stretched at 360-370% and, oh boy, I was impressed. Same accuracy, same penetration at the same distance, but way easier to stretch and reload the gun. There is no need for me to use 2 bands for this length of the gun. One band is more than enough.
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07-21-2018, 03:02 AM | #15 |
the deeper the blue.....
Join Date: Oct 2016
Posts: 498
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Re: Band stretch. Where is the upper limit?
great to hear you guys enjoying the single small ID bands!
have to admit typo in prev post, on that rig am using single 14.8mm primeline small ID [the grey stuff Benthic sell as 15mm] not 14mm. hence the comment would love to try 15.7mm @400%, which seems to be what the 16mm small ID Primeline calipers at. may well be uncomfortable to load, or affect accuracy, but with the 14.8 being so easy to load it's worth a try |
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