NO ONE has yet to realize a HUGELY important band rigging method possible for roller guns. I cannot believe that NO ONE else has figured out this simple and easy method. I got this idea and tried it out on my RA roller conversion and could EASILY pull over 400%. In the end I had to lengthen my roller bands cause my hand kept getting bruised from the recoil.
Isn't the point of the roller to eliminate most of the recoil, if not all?
Isn't the point of the roller to eliminate most of the recoil, if not all?
Correct you are.
I used that extreme to illustrate how EASY my roller band rigging idea is to achieve over 400% with a roller.
Next, we could talk about the advantages / disadvantages of the shorter spear out of a roller gun. :rolleyes1:
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.
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.
That sucks to bad you didn't have some numbers and video from your build.
Any one else going to try?
Correct you are.
I used that extreme to illustrate how EASY my roller band rigging idea is to achieve over 400% with a roller.
Next, we could talk about the advantages / disadvantages of the shorter spear out of a roller gun. :rolleyes1:
Do tell, what is this EASY idea you speak of?
Do tell, what is this EASY idea you speak of?
Aaaaaaaw parker-- I think I'll keep this secret to myself a little longer brother. Lets see if someone else can figure out how to EASILY stretch a single stage roller band to over 400% WITHOUT using any mechanicals.
C, I just gave u another clue;)
Aaaaaaaw parker-- I think I'll keep this secret to myself a little longer brother. Lets see if someone else can figure out how to EASILY stretch a single stage roller band to over 400% WITHOUT using any mechanicals.
C, I just gave u another clue;)
Well, I missed the clue then. I'll be patient, but look forward to learning.
If you choose to look at it that way then it should multiplied by 4 not by 2.
The 2 in that equation has nothing to do with the number of bands/segments it comes from the equation for kinetic energy 1/2(m)(v^2). In my calculations the bands are being modeled as simple springs.
Hau careful when you get to 400% elongation or more. Depending on the rubber you have this is pretty close to the elastic limit. Beyond that it becomes harder to pull the rubber but it will start to cause permanent deformation to the band. This has two problems, one is a dramatic decrease in band life and two because the band does not completely return to normal it ends up being slightly weaker than the amount of force needed to stretch it that far.
As for pre-tensioning, it will improve the power but as Dan mentioned it usually makes it more difficult to load than it's worth. Some guns like the Beuchat have the long main band and then multiple smaller bands on the bottom. This makes loading easier (and slower) but allows for you to increase the overall force slightly.
The force is not generated per segment. It is a total force applied to the wishbone. If two bands applied 360 lbs of force then each would be 180 lbs and 90% of people could not load them. Either way the bands are the same. When you stretch the same rubber by the same amount you get the same force.
I love this discussion! :thumbsup2:
All of these equations has me feeling like --> :crazy:
When you reduced the 115 band stretch by 38.5 you conceded that there are 4 bands instead of two. Think about it.
Uhhhhh....well.....maybe.....uhhhh....and then?.....yep. I think I got it. Four bands would take longer to load, right? 
But seriously, I tried to understand the equations but didn't quite get it......ok....I was completely f**kn' lost.
But I think the greatest yet to come innovation in speargun function would be a band that actually slowly increases speed after you pull the trigger to eliminate the jolt recoil that we deal with now. I simply under power my gun....at least by Fricken Jake's standards. But I like that feel.
But....as much as I laid in bed last night trying to think how the band could start soft and end pulling hard....I don't think it can be done.
So, DA-LS x 3N=FA
DA = dumbass
LS = lack of sleep (I flew in from Hawaii last night)
3N = three nights
FA = f**k all...:D As you can see, I flunked algebra......
reminds me of these . . .
When you reduced the 115 band stretch by 38.5 you conceded that there are 4 bands instead of two. Think about it.
Whether you call it 2 bands or 4 bands it doesn't matter. Either can be modeled as 1 spring that applies a force to the shaft. The roller gun would also have 4 segments. The 2 segments on top that pull on the shaft and the 2 segments on the bottom that pull on the top two segments. Forces are additive so the force of the bottom 2 segments adds to that of the top 2 segments and you get the same result. As you said the bands are the same and I treated both sets the same. In my calculations both guns have two 77 cm bands.
I started with a force value of 80lbs which is a fairly reasonable estimate of an actual band. This number can be higher or lower based on the exact band used. Then using your statement that the bands on a roller and a conventional gun where exactly the same, along with the assumption that the bands where perfectly linear, I calculated the force output of a roller band based on elongation relative to the conventional band.
P.S. Sorry if my calculations are confusing/boring. I tried to explain as I went along and show most of9 my math. Also in case anyone was curious as to my background in this, I study mechanical engineering at Georgia Tech. I graduate in two months (kinda excited).
. . . ., I study mechanical engineering at Georgia Tech. I graduate in two months.
Oh my! That was my major too, but 30-something years ago - and at Auburn.
Are we forgetting something here? I'm fascinated by the scientific brilliance that is manifested on this thread. But I am beginning to wonder what we're overlooking. As I have been planning how I will rig my guns for this little experiment, I have realized that I will be chasing an objective that is irrelevant to the purpose for me for having converted my longer pipe gun to a shorter roller gun. The debate that is being presented here, and that I am being challenged to prove through video presentation, has to do with the power of one being equal or greater than the power of the other. While this argument is interesting, it is not why I chose the roller muzzle concept. Dan, if I am to make all things equal, I will be putting bands on my conventional guns that I don't normally hunt with and that would potentially cause my gun to be over powered with too much recoil and muzzle lift. For example, I found I could put a 17.5-18.0mm band on my roller at 320-350% stretch and have a gun powerful enough to make open water shots on bigger fish while using a gun that is shorter and more desirable on the reef, in caves, ledges etc than my longer guns rigged with 2-3 16mm bands. My shortened roller gives me this ability with minimum recoil/muzzle lift. So in my application I have already gained an advantage by using the roller muzzle concept over using my standard gun and set up. How you ask? By having a gun that is better suited for tight, close work without sacrificing taking a longer range shot when I'm out in open water. Sure, I could use my standard gun (and have for years!) in those same environments, but it is always a trick to maneuver the longer gun and take shots with your thumb while the handle is back behind your head. So we have taken shorter guns out with us to hit the reef and holes, but not had the range for the open water shots. I'm sure I could increase the range of the shorter guns by increasing band diameter and shortening the band length, but then we get into the issue of an over powered gun. So that is why I have found the roller muzzle to be the perfect tool in that scenario. The idea of the roller conversion didn't originate because I was looking for more power than my conventional guns, but to have a manageable gun with the ability to take longer shots when needed. I would never shoot 17.5-18.0mm bands on my traditional guns (unless a big tuna gun with 3/4" shaft?), but on the roller that size band is manageable and gives me the rage I need on a shorter barreled gun. Swimming from shore as we usually do on the Big Island, it is routine to hit all of the reef, lava rock caves and ledges, pinnacles with pounding surf and surge, while eventually reaching deeper water and open water game. So having one gun that is a "crossover" in ability is really convenient. Launching from a boat as we typically did in Florida hitting mostly open water a conventional gun is a perfect tool. Does this make sense?
So while I will be glad to rig the guns with equal power configurations for this experiment, I'm afraid that I will be making comparisons between guns with set-ups that I would never realistically shoot. So while I am happy to assist in the practical debate of "Equal or Greater Power", I need to let you all know that It occurred to me that this is not my objective for choosing the roller gun concept. I still love my conventional guns, especially my DIY Hybrid. But for the applications of low vis, tight space in reef and inside reef caves, I am thrilled with the results of having a shorter gun and the penetration/range of the 17.5-18mm band..
I have enjoyed the debate. It's human nature to find an explanation and validation in choosing between two different models of a given tool. I race two stroke dirt bikes. I like the "power band" of these beautiful bikes and can out ride a four stroke all day long. But on single track and long steep hills, give me my four stroke to get the job done. I can't argue which bike concept is better, but I know which is better for me in my given circumstance.
The 110 I have is ready with both muzzles. The roller muzzle for the 90 Pathos is in the mail. I'm not sure I will have the wood conversion done for this experiment. I would prefer to build a wood gun around the roller muzzle design for better hydrodynamics. Maybe a later video showing the wood gun comparison?
I hope I made my explanation clear. Also, I hope you all will continue to work out the physics of it all as you continue to debate the topic. You guys are crazy smart!
Dan, the band length on the 110cm roller is 48cm which is a coefficient of about 330% (3.3) based on the Aimrite trigger being front-latch and not rear. Let me know what lengths, band width and stretch coefficients you would like to see in this video. I will accommodate, then I will compare the set ups I normally shoot to show how in my application the roller has been effective. 
Aloha,
Makoa
:laughing3::laughing3::laughing3:
reminds me of these . . .
Well said makoa. Different strokes for different folks. I still think 3 x 14mm would be much more pleasant to shoot on your DIY Hybrid while still offering plenty of range and power for a double wrap of line.
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