Perfecto! Now we're cooking.
A milk jug filled with sand and a measurement of spear penetration will suffice.
Posts by Dan
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Link fixed.
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About the size of a door latch <img src= " class="smiley" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x" height="23" width="23" loading="eager" data-tooltip="biggrin" aria-label="biggrin">
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Would be nice
Can we see pics of the guns side by side to whet the appetite?
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Gabriel, I'm sorry I didn't make myself clear. The retractable shark spike IS available.
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The Roller Gun will have more power and more range
That's the only part of your post that meaningful, but it's also incorrect. The rest/your description of the two spearguns is a fantasy that I can't follow. It's nice that Marco and George can though.
If you choose to retort Jon, draw a picture of those two guns. I've only seen your guns finished and in various stages of building, but I assume you draw at least some of them first. So I'm sure you can sketch something for us with minimal effort.
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I fixed it. This is the snippet you want, notice there's no s at the end of http.
Codehttp://www.youtube.com/watch?v=WOSqOyQWwRE -
Why not.
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Welcome to Speardiver. Nice pics.
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Thanks Makoa.
When talking about euro speargun lengths it's hard to know what everyone means, because there are different ways of measuring. For example often the stated length of a gun is simply the length of the barrel, be it aluminum or carbon. But if the objective is to have a clear idea of the power and range of a gun that number can be misleading. For example the handle of the Speardiver Phantom speargun because of its reverse trigger mechanism adds another 10cm of band stretch, so together with a 110cm tube produces true 120cm of band stretch.
So the only way to provide a correct idea of a gun's power/range potential is by stating the true band stretch, which is from the muzzle hole or pulley, to the furthermost tab/notch on the shaft. But this can also be misleading because different shafts have the tabs/notches in different places.
This is the reason I decided to state the length of all Speardiver guns based on the distance from the foremost muzzle band hole to the mouth of the trigger mechanism. Because theoretically you can have a shaft that has the tab/notch right at the mouth of the mech. This measurement will be consistent regardless of the shaft used.
That said, you referred to your gun as a 110 but it appears to have only 100cm of maximum band stretch potential. Probably a little more if you got a shaft with a tab closer to the mech, in all likelihood I'd call your gun a 105. If I were to build a conventional speargun to test against your roller I'd make sure it had 105cm of true band stretch potential.
Back to your measurements. You have an actual total band stretch of 141cm. Divide 141 by 48 (the band length) and you get 2.94 which means you're stretching each one of your two bands to %294, not %330. Neither Xan nor Gabriel can argue with this number. It can be considered that the tied wishbones further cuts into this number, but we'll use Xan's extra 5cm of pulley circumference to offset it
even though I think it's too much. The band is nestled in the pulley's track and there's no way half the circumference there is 5cm.What does all this add up to? You have 105cm long speargun with two 17.5mm bands stretched to a fairly conservative ratio of %294. Take that same 105cm speargun and rig it with two 16mm bands stretched to %350, and I think you will at least match if not surpass the roller in power and range, without overpowering the gun. If you'd stretch the 17.5mm roller bands to %350 you'll encounter recoil issues, the gun is now overpowered. Also with a roller you're stuck loading both bands together in one pull, this seriously cuts into how much you're able to stretch the band.
That's quite a hole in the cubera Hank.
A speargun thread with no drama and almost 2000 views, not bad
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What is the distance along the bottom of the gun, from the roller muzzle pulley to the point where the band ends when gun is loaded to maximum power please?
And the distance along the top of the gun from the pulley to the furthest tab on the shaft?
Could you please clarify what you mean by "shortened 110 roller". I assumed that you had a conventional 110cm speargun and just switched out the muzzle without cutting/shortening the barrel.
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Xan, congrats on graduation.
So Dan was right all along.
I like the sound of that. But I'm not going to pretend I understand the formulas fully. This is high school math and for me was 30 years ago. After being done with it I was happy to allocate that space in my brain to other more pertinent stuff. I could sit down and reason it out all over again, but that would take time which I'd rather spend diving or making new gear. More so because I see the calculations as unnecessary in this case, using simple logic it's evident there's no difference between the roller and conventional set ups.
Stock length and consequently band stretch are almost the same, bands are the same. The only difference is that with the conventional speargun each of the two band's two half segments are contracting simultaneously towards the muzzle YES THAT'S 4 HALF BANDS CONTRACTING AT THE SAME TIME, and with the roller each of the two bands is contracting completely from end to end. I see no way for that in and of itself to increase the band's pulling power. Reduce recoil.. maybe slightly, but in reality a more significant portion of the recoil is reduced because the roller bands are stretched less, which makes the roller appear more manageable.
Makoa, I didn't really expect you to go through with all that building. I recognize the good intentions but most of us have busy schedules and when we have free time we'd just rather be diving. So spending time and effort just to prove something quickly loses its appeal. But something does need to be pointed out again: in this case power is synonymous with range. So when I focused on proving that a roller is not more powerful than a conventional speargun, this also encompassed the myth of the roller having more range than an identical length conventional speargun.
Also your 110cm roller's band length can't be 48cm. That would make it %450 stretch.
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Nice mutts.
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When you reduced the 115 band stretch by 38.5 you conceded that there are 4 bands instead of two. Think about it.
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In any case your calculation is wrong, I just grabbed the most obvious number. If you're going to subtract 38.5 from 115, then it should be (320) not (160), because looking at it the way you're doing there are 4 band segments.
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Why not pre-tension the band(s) to 150%? Wouldn't that yield a higher velocity shaft leaving the gun?
Because then it becomes very difficult to load.
One rail gun and a roller muzzle is all you'd need. It wouldn't take long to swap out the muzzles
Well and bands for each muzzle type.I already did it, two years ago actually. The results are this thread. I was just so disgusted with the whole thing I disassembled the gun immediately. These are pics of the gun I built.
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If you choose to look at it that way then it should multiplied by 4 not by 2.
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Xan, in 2(160)(115-38.5) why did you subtract 38.5?
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A euro speargun in its most conventional form is a chest loading speargun with a hollow pipe for a barrel, a rear integrated handle/trigger mechanism, and a simple double notched shaft. The shaft has a round notch to match the trigger mechanism round sear.
There are intricate wood euros, with enclosed track and tabbed shaft. The only common denominator you will find here is a rear handle and chest loading.
A Riffe euro even has a butt extension, I think that pushes it past being a euro.
The phantom will be just like your cressi, just newer.
You don't even know what model Cressi he has, nuff said
