Travel Rollergun Build

[Otolithco]

I was able to dive for a couple hours this weekend but the vis was poor and not much life. I took a couple calico and the gun worked great. Only downside I need to try to address is that it's a little muzzle heavy.
Hopefully I can get some video footage soon

[ShootIt]

That is amazing work.

[FreediveCA]

Originally Posted by Otolithco

I was able to dive for a couple hours this weekend but the vis was poor and not much life. I took a couple calico and the gun worked great. Only downside I need to try to address is that it's a little muzzle heavy.
Hopefully I can get some video footage soon

If I were to have guessed one end was heavier I would have guessed the butt end with the dowels and all on that half. You going to do anything to fix that, or is it not too bad?

[Otolithco]

Originally Posted by FreediveCA

If I were to have guessed one end was heavier I would have guessed the butt end with the dowels and all on that half. You going to do anything to fix that, or is it not too bad?

Right now, it's usable, just annoying.

Both ends were too negatively buoyant originally. I replaced the stainless trigger mech pins and roller axle with carbon fiber rod. I also made a foam loading pad that fixed the back end. I'm going to try to replace the stainless dowels with carbon fiber which should fix it. If/when I build another, I think carbon fiber dowels would be the right way to go. Other option would be keeping more wood which somewhat goes against the purpose of small, traveler gun.

[spearq8]

I think for the dowels Ti64 would be a good alternative to CF or SS. It is very light and very strong. I don't know but CF for rods that will be removed and installed many times seem like not the best.

[Jamil]

Originally Posted by Otolithco

The dowels are 3/8" and the sleeves are just a hair over 3/8" ID. I glued the sleeves although they were snug as is.
It is a little tricky when installing these as you need the whole system to be perfectly parallel AND a perfect match to the other side or your stock/track won't line up. Otherwise, it might never fit together without cracking the wood. An option would be to drill slightly more than necessary for the sleeves, then glue them in place with the dowels installed, and shaft in the gun. The only danger here is that the dowels would be slightly off parallel and you would never get the gun apart.
I made a little stencil to ensure I was drilling in the exact same location for all the sleeves. I still think it was part luck that it fit together so perfectly.

Another thing to consider regarding stock thickness is that the forces are different on a rollergun. Rather than on a regular setup, where the bands are trying to bend the gun, the force in a rollergun is parallel with the stock (just pushing the two halves together). You won't need nearly as much thickness as you think (however, it still needs to float). Not to mention there is very little recoil so you don't need a lot of mass.

Thanks. What was the length of the dowels? I will go a different direction to ensure i don't have issues with alignment. You were lucky as you mentioned, i might not be so i will do the sleeve/dowel step on the blank (after its cut in half, before i do any cuts/slots/shaping). then i will use the router for the cuts/slots. I believe this direction is safer. I see your thickness comment but I'd still want to make the gun a bit beefy at first to ensure i can play with ballast. I do not want the gun to be but or muzzle heavy. Especially that I'll be using Neptonic systems roller which is heavy by design.

Jamil

[pernicia]

Originally Posted by Otolithco

Right now, it's usable, just annoying.

Both ends were too negatively buoyant originally. I replaced the stainless trigger mech pins and roller axle with carbon fiber rod. I also made a foam loading pad that fixed the back end. I'm going to try to replace the stainless dowels with carbon fiber which should fix it. If/when I build another, I think carbon fiber dowels would be the right way to go. Other option would be keeping more wood which somewhat goes against the purpose of small, traveler gun.

Not sure if some divynicell plugs would help much, or routing a deep channel on the bottom side, epoxying some divynicell piece (6" (L) x 5/8-3/4" (W) x 5/8" (H)) may help.

[Otolithco]

Originally Posted by Jamil

Thanks. What was the length of the dowels? I will go a different direction to ensure i don't have issues with alignment. You were lucky as you mentioned, i might not be so i will do the sleeve/dowel step on the blank (after its cut in half, before i do any cuts/slots/shaping). then i will use the router for the cuts/slots. I believe this direction is safer. I see your thickness comment but I'd still want to make the gun a bit beefy at first to ensure i can play with ballast. I do not want the gun to be but or muzzle heavy. Especially that I'll be using Neptonic systems roller which is heavy by design.

Jamil

That's a good idea Jamil. That way, you would only need to make sure the dowels are parallel to each other. The dowels were originally 3" per side then I cut them to 2".

[Otolithco]

Originally Posted by pernicia

Not sure if some divynicell plugs would help much, or routing a deep channel on the bottom side, epoxying some divynicell piece (6" (L) x 5/8-3/4" (W) x 5/8" (H)) may help.

That would probably do the trick. Hoping I can correct it without cutting into the stock though. As-is, it's probably not enough of a problem for me to do that.

[Jamil]

you have gotten me thinking a lot on this man which leads to more questions:

Did you leave any clearance/tolerance between the dowel and sleeve? am worried that if i make it a perfect fit, it wont let air go out when inserting the dowel inside the sleeve! (think like pneumatic pump concept, which holds oil inside the sleeve).

did you consider permanently epoxying one side of the dowels to one half of the gun (without the sleeves)? this way you will minimize chances of loosing the dowels during transportation and make it quicker to install. Am thinking of going this direction but worry on loosing structural strength by eliminating the sleeves from one side!

I might go with 6" long dowels. any thoughts?

By the way if you want i can create a new thread for this (not to high jack your post) but i thought it would benefit readers who check your post. what do you think?

thanks,
Jamil

[Otolithco]

No worries on high jacking the post. I like this sort of discussion.

To your questions
The dowels and sleeves were very tight when installed. So much that they make a vacuum popping sound when you pull the gun apart. It wasn't enough to prevent it from working smoothly though. I suppose you could cut/grind a small groove down the dowels to ensure there isn't a problem.

I did epoxy one side of the dowels into the gun. They are permanent on the back piece. My thinking was the same as yours here in that it keeps things simple. Also, I have dowels AND sleeves permanently fixed in the rear half of the gun so you could go that route if you're worried about strength

You mean 6" dowels on each side? Or, 6" total? In my opinion, either would be overkill. I have cut mine down to about 1.5" exposed and it makes no difference from the 3" exposed. Now, if this weren't a rollergun, I might want a little more dowel length.

Hope this helps!

Originally Posted by Jamil

you have gotten me thinking a lot on this man which leads to more questions:

Did you leave any clearance/tolerance between the dowel and sleeve? am worried that if i make it a perfect fit, it wont let air go out when inserting the dowel inside the sleeve! (think like pneumatic pump concept, which holds oil inside the sleeve).

did you consider permanently epoxying one side of the dowels to one half of the gun (without the sleeves)? this way you will minimize chances of loosing the dowels during transportation and make it quicker to install. Am thinking of going this direction but worry on loosing structural strength by eliminating the sleeves from one side!

I might go with 6" long dowels. any thoughts?

By the way if you want i can create a new thread for this (not to high jack your post) but i thought it would benefit readers who check your post. what do you think?

thanks,
Jamil

[Jamil]

Very much so Otolithco, thanks .

[Otolithco]

[Jamil]

Great catch. How's the gun performing? Any valuable learning, comments you fix it recommend after trying your gun?

[Otolithco]

Originally Posted by Jamil

Great catch. How's the gun performing? Any valuable learning, comments you fix it recommend after trying your gun?

Really happy with how the gun is performing.
Something to think about is the bottom-rear wishbone catch. This connection will be shock loaded over and over. My connection here raised slightly at first but hasn't failed. I took a very simple approach to these but I'm sure there are several methods.
Good luck and keep us posted