Carbon fiber stocks - DIY tinkering

[hpmr]

So, I thought I would share some DIY carbon fiber stock work I've been messing around with. No prior experience working with carbon fiber and resins, so much has been done through trying and failing. And it is kinda fascinating how "low-tech" one can work this high-tech material, with basic hand tools you'll find in the garage.

My primary motivation for doing this was the lack of good after market stocks meeting my requirements. Making my own stock I aimed at combining all the treats from diffirent rifle stocks I liked. Well that was the theory atleast...

The method I'm using is to first shape a high density foam core, and then wrap it with multiple layers of carbon fiber cloth, building the outer shell. For the first rifle stock I made, I wrapped the carbon fiber around the foam core and let the resin "air dry". It worked out OK, but it wasn't optimal. So for the second build I added a vacuum sealer to the mix.

The basic tools used: polyutherane/pvc foam, carbon fiber cloth, resin, knife, scissors (carbon fiber cloth really dulls them fast), wood file and sanding papers. I later added the vacuum sealer machine, breather cloth and peel ply:



In order to get the necessary thickness (and to improve stiffness) I cut out carbon fiber cloth matching size of the foam and then stacked the polyurethane foam plates and sandwiched them with carbon fiber wetted with resin.







For maximum bonding it was wedged between some stiff boards and clamped down and left over night:



Once the sandwiched core was done I started to shape it according to the sketch. The stock was supposed to be "ergonomic", and a hybrid adapted for both off-hand competition shooting and hunting... (The mk1 turned out way too bulky):








13.8 oz, so its pretty light. However, I screwed up while bedding the action/chassis in this one, and at the same time I realized that the ergonomics wasn't quite there yet. So back to start...

 

[BCsteve]

Following...

 

[IdahoFF]

If you haven't already found this during your research, for strength alternate the orientation of your plies. I.e 45,90,45,90, etc depending on how many plies you use. Off to a great start. Pm me if you have any questions about CF layup, was a CF technician for about 8yrs, however I wasn't building stocks.

 

[hpmr]

If you haven't already found this during your research, for strength alternate the orientation of your plies. I.e 45,90,45,90, etc depending on how many plies you use. Off to a great start. Pm me if you have any questions about CF layup, was a CF technician for about 8yrs, however I wasn't building stocks.

Yes, I've been trying to alternate the direction through the different layers (trying to get the last layer somewhat straight for "the looks" - which seems to be alot easier said than done...) I later switched to braided carbon fiber tubing, which seems to be great for stiffness.

 

[FlyGuy]

Very cool

 

[hpmr]

After the initial attempt (with the failed bedding) I decided to do some changes. The first rifle I was bulding a carbon fiber stock for was a Blaser R8 straight pull. The action on that rifle somewhat special, as the barrel is fixed to a small "chassis", and the bolt locks directly to the barrel.



I found it hard to bed this "action" to the stock, especially making the sidewalls stiff enough.



A solution and work-around for me was to sacrifice the original stock, which was kinda rough, worn down and ugly anyway. I cut out the section that holds on to the action, and joined it to the carbon fiber reinforced foam core. The foam (white) I used on this stock is called Bonocell. I would not recommend it, as it is a bit to soft. I later switched to Divinycell PVC (green) which is a whole different league.

After I glued together the foam and the stock middle section, I began take two on the design:



When I was happy with the stock design, it was time for carbon fiber cloth. I brushed resin on the foam core, waited a couple of hours for it to become sticky, and then wrapped the cloth on the core. This was then wrapped in peel ply and breather, before everyting got tucked into a vacuum bag and sealed off.



I wasn't sold on the grip area, so this needed some modifications (excuse the mess):


After I was done with the adjustments, it got a couple more layers of carbon fiber:



I gave this stock a finish of epoxy top coat, some sponge camo and matte clear coat. I probably could have / should have done some more work on the finish, removing some dings and scars, but I was to eager to finish it up and go shooting. The grip areas was done by mixing epoxy and blaster sand.



Here it is dressed up with a Krieger 280AI barrel:

 

[hpmr]

...and the new stock was a shooter, and it did get to see some action that fall. Here are a few action shots.

 

[Jason Snyder]

Nice work!

 

[SCHUNTER73]

Extremely impressive…I admire your ambition.

 

[RepeatPete]

That looks awesome! I recently went down a very similar path: first using the too soft white foam, then switching to the green board foam, bonding in the inletting section of the original stock, and also using woven carbon sleeve. I couldn’t get it to conform well to my mold, but letting the first coat of resin get tacky and then using that to hold the carbon sleeve in place is a great idea, thanks! When the resin was tacky, how hard was it to slide the sleeve over the whole mold?

Custom Carbon Fiber Stock

I’ve decided to jump into the deep end and make my own carbon fiber stock. This will be going on a M700 7mm Rem mag, which currently wears a wood stock. I did a ton of research here, read a lot of @Formidilosus posts, and decided I wanted a vertical grip, negative comb stock. I’m taller, so...

rokslide.com

 

[BCsteve]

Great work!

 

[hpmr]

That looks awesome! I recently went down a very similar path: first using the too soft white foam, then switching to the green board foam, bonding in the inletting section of the original stock, and also using woven carbon sleeve. I couldn’t get it to conform well to my mold, but letting the first coat of resin get tacky and then using that to hold the carbon sleeve in place is a great idea, thanks! When the resin was tacky, how hard was it to slide the sleeve over the whole mold?

Custom Carbon Fiber Stock

I’ve decided to jump into the deep end and make my own carbon fiber stock. This will be going on a M700 7mm Rem mag, which currently wears a wood stock. I did a ton of research here, read a lot of @Formidilosus posts, and decided I wanted a vertical grip, negative comb stock. I’m taller, so...

rokslide.com

Sliding the sleeve over definitely was tricky. Once the fibers connect to the resin they start having a will of their own. The best way I found was to split the sleeve in two parts, overlapping in the grip area. This was also benefitial to the overall strength, the grip area being a potensial stress point. I compressed the braided tube all the way, making the diameter as big as possible. I then slid this «sock» over the stock without touching the resin. Once I reached the middle point of the section I was working on, I gently pulled the sleeve out to make it narrower and wrapping around the foam core.

When working on the first layer I also used thumb tacks to hold the sleeve in place while adjusting the fit and wetting the sleeve in resin. I did the same when wrapping it with peel ply, making sure the peel ply held the carbon sleeve tightly to the core. I removed the tacks when I put the stock into the vacuum bag. I used the same technique on the second layer, however as I couldn’t use thumb tacks on the all ready hard carbon shell, I replaced the thumb tacks with rubber bands holding the sleeve thight to the mold. The rubber bands stayed on through the vacuum prosess and was easily removed afterwards.

 

[fshaw]

Impressive. The pioneer spirit on display.

 

[TaperPin]

Looks great! How light did the second stock end up being?

 

[hpmr]

Looks great! How light did the second stock end up being?

560 grams (with sling studs), so approx. 19.7 oz.

 

[Antares]

Impressive. The American pioneer spirit on display.

Which part of those posts makes you think OP is from the US?

 

[fshaw]

Which part of those posts makes you think OP is from the US?

Sorry if that offended.

 

[fshaw]

(Name your country/continent) pioneer spirit on display. Guess I was showing my bias because I’m an American as are most posters here. Didn’t mean to step on any toes. Impressive regardless of the origin of the craftsperson (may not be male).

 

[hpmr]

No offence taken! I did spend a year in North Dakota while studying, but I'm from Norway

 

[fshaw]

Edited the original post, I hope the “pioneer” part isn’t too U.S.-centric. Your Norwegian ancestors would be proud. I should have looked closer to see that it was a Stag not an elk. Cool stock at any rate.