Rollergun suggestions

[taziedevil11]

so ok im building a rollergun. nothing tooo fancy, i just want to able to dive with something i made. im thinking that i should probally pick out the size spear shaft and then build the gun to fit it. so my question is....with me mostly doing close shore kelp dives what size shaft or gun size do you all think i should try.

 

[Old Man Dave]

How long is a piece of string? You gotta help us out here. Where in the world are you diving? What size and type of fish? What sort of length/power guns are in use in your area? Roller guns can be made to store more power in a very long gun or to make a very short gun with extra power. All depends.

Dave

 

[taziedevil11]

my appologies...i dive in the pacific NW, near seattle. biggest fish ive gotten so far was just under 10lbs. mainly greenling, surfperch, lings and flounder. going for shorter/extra power for the maneuverability. most guns ive seen used around here are mainly 42'' and under, and i use a 38''. the visibility keeps shots to a pretty close distance, its about 15ft on a good day. so distance isnt an issue.
ben

 

[Old Man Dave]

Hi Ben, another over the pond member . Well I'm not an expert on building guns and also my experience is with euro and hence metric measurements. However I have had a hand in making a fair bit of gear including some guns. If you put "rollergun" into the search function at the top of the page you'll get a lot of info. You will see a nice little rollergun built by my brother Foxfish amongst quite a few others. Good luck to you and ask some more direct questions if you need to after you've read up a bit. Let us know how you get on.

Good Huntin'

Dave

 

[taziedevil11]

thanks for the help. its goin to be awhile till i get it made. heading to japan for awhile so i wont get a chance to work on it. although i will be taking my travel polespear...i'll design it, and post the plans. later
ben

 

[Old Man Dave]

My mate Ed (DB member "Portinfer") spent quite a bit of time in Japan. He was really taken with the place. He's now into building guns. See his efforts by searching "Teak 80". Never been to that area of the world myself but have been seeing the sites of the USA on holidays etc over the last decade. Really like the States myself. Last year was in New York and all places north east. Year before was in California and all places south west.

Have fun

Dave

Added link for teak 80 http://forums.deeperblue.net/homemade-spearguns/63452-teak-80-part-one-stock.html?highlight=teak

 

[taziedevil11]

yeah well ive only taken up diving in the last few years so the only place ive been is up here in washington. but im looking forward to diving in japan...i'll be most likely diving off okinawa. i guess if you can get past all the sharks its a great place to dive...
thanks for the link
ben

 

[scrounger]

you could built a gun that is the same size as you gun is but build it roller style. that way when you water clears up you will be able to poke out a bit more. i shoot a riffe mt1 that is also a 38" gun most of the time and when it cleans up i always want more gun.

 

[taziedevil11]

i guess i never thought about that...i guess for some reason i had it in my head that i needed a totally different spear for the rollergun...have any idea what size bands i should use?
ben

 

[SpeerO]

I have a question too since im also about to build a roller for the first time. My question is how do u consider/calculate rubber length for a roller, since its not the usual hole at the muzzle?

Thanx in advance
Zane...

 

[Fondueset]

Max 3.5 to 1 stretch is the general rule.

 

[scrounger]

do not forget to add the extra lenght under the gun for band stretch.

 

[taziedevil11]

ok thats one of those things i just dont understand...wood yes...bands no. what do you mean by 3.5 to 1? im assuming you mean amount of stretch to length of band. i just want to be sure.

 

[Fondueset]

Right - That's what the speargun types say. Latex manufacturors say never go beyond 300%. I think anywhere from 2.5-3.5 based on what I've read. Personally I've done zero experimentation though.

 

[SpeerO]

Taziedevil.. theres a formula to go by when choosing ur band lengths.. So u measure the distance from the hole where the rubber sits till the notch in the shaft then u multiply by 2 then divide by the coeficient wich is from 3 to 3.5. 3.5 will give u the shortest rubber length ie most power.. and the 3 gives u the longest size. So u can play with the different coeficient and see where u like it. Its good to always start with the longer setup.. 3:1 then shorten up till satisfied. Tho u have to put in mind that the shorter, the more recoil the less rubber life... so its a balance between both


Now what i dont quite get is since the hole is not in the begining of the gun how do i measure the band stretch? Do i measure the distance from where the rubbers r gonna be tied (lets say middle of the barrel) then all the way up the muzzle and down to the shaft notch?? Someone please explain

Thanx
Zane

 

[Fondueset]

If you look at a roller gun the wishbone is at rest right at the end of the barrel. So your band length will be determined by the distance between the resting position of the wishbone and the notch or fin on the shaft - in otherwords the distance you want the bands to stretch.

 

[Old Man Dave]

If the band measures 10 inches unloaded then it will measure 35 inches in the fully loaded position. This is easy with euro bands that are 2 single lengths that screw in at each end. Loop bands as favoured on american guns need a bit more calculation as you have to allow for the bit that fits through the front hole. They still strech to 3.5 times their length when loaded though. Roller guns need a bit of maths to work out as although the strech is 3.5 times it starts underneath the gun, runs forward and then back. The front anchor point for the bands under the gun is between 25% and 30% of the gun length back from the front. Any further back and the bands cannot fully unload on top and hit the nose (rollers) with too much force. Roller guns are usually short as you have to reach the very front of the gun to grasp the bands to load them.

Dave

 

[SpeerO]

Ok thanx fellaz! ill get this roller project rolling soon!!

Theres just a few bunch of guns in line before this

Oh.. another question just popped in my mind now... when putting the rollers do u put that bolt thru the wood directly or do u put some kind of sleeve into the wood then run the bolt thru that sleeve?




Zane...

 

[taziedevil11]

thanks...ok up to speed on the regular gun bands, and i would think you may be right on how the bands work with the rollers, it makes the most sence to me anyways...and ok speaking of rollers, do ya think there is a difference between mounting the rollers vertically or horizontally...most of the guns i have seen are vertically mounted. but i think the horizonally mounted rollers would offer a straiter trajectory.
ben

 

[foxfish]

Here is one I built a few months back.