Gunsmithing making a composite stock from scratch?

[1shot2kill]

if i wanted to make one from scratch what sort of materials would be the best to use?
its 4am and i have a hamster in my head running on the wheel with potential project ideas

 

[sixpack340]

Re: making a composite stock from scratch?

I know this has been discussed before, but I'd search for something like surf board material. That shits pretty stiff and wouldn't be too hard to rough in to a shape and then finish with a body putty of some sort. Though I wonder if you should add some sort of steel or aluminum reenforcemrnt??

 

[LRI]

Re: making a composite stock from scratch?

You start this sort of project by making/getting a "plug". A plug is the shape of the part your trying to make.

Then you make your molds. Each side done individually.

How you lay them up depends on what your after.

A great place to get ideas for laying up stocks is visiting an RC airplane forum. Without too muxh effort you can find build threads where guys are scratch building planes using some rather sophisticated processes.

None of its easy/cheap, but they sure do come out nice.

Good luck

C.

 

[jrm850]

Re: making a composite stock from scratch?

I built prosthetic sockets for a few years using a technique that would probably work well for a one off composite. We used plaster for a sacrificial plug, but in this instance the plug would stay put and is probably pretty important for rigidity. I'm not sure what the grey stuff McMillan etc uses but it would be a good start if you can figure it out. If not, I would just make a rough mold and fill with some two part polyurethane foam. Carve the plug to shape leaving it undersized enough so that your layup will be at final dimensions. Your layup will be applied to the carved core using fiberglass/carbon fiber/kevlar or whatever else you want to use. Then comes the tricky part of pulling a PVA bag over your concoction. We used ready made sleeves but you may have to make your own to account for the different diameters needed for forend and butt. Roll your PVA bag in a damp towel to soften it and make it liable. The pva tube is open top and bottom. The bottom opening is sealed to a vacuum pump and the top is where you pour your epoxy when you are ready. have a couple of short pieces of 550 cord handy for tying off the top opening when you are ready for full vacuum and for pulling the epoxy down over your layup. pour enough mixed epoxy in the top of the pva bag to saturate your layup.Pull it down to the bottom of the stock with the 550 cord. Once the epoxy is staged, tie the top of the pva bag off to prevent sucking any air into the setup when the vacuum is on. Turn on the vacuum pump and use either the 550 cord or a small roller to work the epoxy into your layup and push all the excess to the bottom. Be careful not to let any epoxy into your vacuum pump.

let it kick over while the vacuum is running and you have a blank. I would plan on doing all of your inletting on a mill becasue the pva bags don't like sharp corners and would be likely to rupture. The surface finish is fantastic with carbon fiber and you do not end up with excess epoxy in the layup.

 

[vvillium3]

Re: making a composite stock from scratch?

I've always wondered how good stock companies put the two halves together. Obviously they must fiberglass/carbon the two halves together, but they must do it from the inside. I've never seen a seam line on a McMillan, and the transition from one side to the other always looks great.

To the OP, there is a great site with a ton of composites information readily available:

Compositescentral.com

Good luck

 

[seanh]

Re: making a composite stock from scratch?

what jrm850 says.

Go do some research on wet layup vacuum bagging techniques.

As mentioned, this is common in RC circles...

ridged polyurathane foam for the core with a CF, Kevlar or fiberglass cloth overlay and maybe one of the following resins
http://www.smooth-on.com/Urethane-Plastic-a/c5_1120_1325/index.html

http://www.smooth-on.com/Urethane-Plastic-a/c5_1120_1208/index.html

http://www.smooth-on.com/Urethane-Plastic-a/c5_1120_1156/index.html

ridged foam to consider...call them first to get an idea of stiffness.
http://www.smooth-on.com/Rigid-and-Flexible/c10_1122/index.html

http://www.shopmaninc.com/foam.html

 

[1shot2kill]

Re: making a composite stock from scratch?

Thanks guys