Carbon Fiber on Stocks -- How to?

[nilebartram]

Has anyone used or laid up carbon fiber on a rifle stock? I have some un-finished Lee 6 stocks and I was thinking of using carbon fiber to finish them. Am I biting more than I can chew? I have some sail boat buddies and they say it is harder than fiberglass. I have a lot of experience with fiberglass. please advise. nilebartram

 

[Dusty Stevens]

Has anyone used or laid up carbon fiber on a rifle stock? I have some un-finished Lee 6 stocks and I was thinking of using carbon fiber to finish them. Am I biting more than I can chew? I have some sail boat buddies and they say it is harder than fiberglass. I have a lot of experience with fiberglass. please advise. nilebartram

You can lay it up like fiberglass and its basically the same except harder to cut. The issues come in when actually molding and curing it like for actual structural parts like a boat (which i have experience in) or higher end car parts. It is actually cured at a very high temp in an acetylene atmosphere. When you just use the cloth and add the resin its simple if youve done fiberglass. The difficulty comes in using the impregnated resin in the CF weave.

 

[Texas10]

Not hard at all if you have some basic equipment like a vacuum pump and bagging supplies, peel ply, batting, etc. The problem with CF is you're going to be using epoxy instead of polyester or vinylester which are much more "sticky"and tend to hold down reinforcing cloths better. Epoxy, combined with the inherent stiffness of carbon fiber will want to lift off the stock where it is on a curved surface. To keep it tight against the stock you'll need to use a vacuum bag or tightly wrapped peel ply. There is also a shrinking wrap that you can use that will tighten up as heat is applied, frequently used on tubular layups.

Since you have experience with fiberglass, you may decide to make a mold of your stock and vacuum bag the CF into the mold if what you are looking for is a CF appearance on the final product.

There are some really cool carbon fiber/ colored fiberglass blends of cloths. I've also used a carbon fiber and kevlar blend that produced a yellow and black weave appearance on a project.

Most of what you'd need is available at this company: https://www.acpcomposites.com/

A inexpensive vacuum pump can be made from a vacuum pump purchased online and some 4 inch PVC to act as vacuum holding tanks along with a vacuum switch. https://www.amazon.com/dp/B012CFTYX4/?tag=accuratescom-20

A standard shop vac is also quite effective, albeit extremely noisy. A *hot box* made of a cardboard box and a hair dryer is essential to warm the project as it cures.

 

[butchlambert]

Al Flores helped me build 2 BR stocks. One was redwood and carbon fiber cloth. The heavy stock was done in walnut and carbon fiber cloth. Yes, we used vacuum bagging and highly recommend it. I liked the look of wood and did not want the cloth covering the outside.
Al was able to hand select the redwood to find the lightest pieces. All wood do not weigh the samed.

 

[MClark]

I have done barrel channels on a couple rifles, all with full stocks.
Carbon fiber is stiffer than glass when doing lay up and tends to fall apart at edges.
If you are asking these questions I would suggest practicing on a junk stock a few times before the real one.

 

[rickiesrevenge]

If you just want it to look like carbon fiber you could have it dipped.

 

[Downhill]

Just a question. If applying carbon fiber cloth with the epoxy and not curing at the high temperature, as Dusty mentioned. Would the Strength of the carbon fiber cloth be no better than the epoxy used to apply it? I am under the assumption that it needs the high temp to achieve its strength and stiffness.

 

[MClark]

High temp cure resins are used for a couple reasons.
The epoxy needs to be cured at a temperature higher than the part will be used.
To layup large parts that take a long time to assemble.
When using Prepreg carbon (pre impregnated with resin). The prepreg is shipped cold so it doesn’t cure, By requiring high temp cure it increases shelf life, plus it’s likely to be used in parts used hot. Also it has the correct amount of resin so excess doesn’t need the be sucked out when vacuum bagging.
the correct room temperature cure resins works near as well. What we are making doesn’t require the strength of a jet plane wing.

 

[Texas10]

Just a question. If applying carbon fiber cloth with the epoxy and not curing at the high temperature, as Dusty mentioned. Would the Strength of the carbon fiber cloth be no better than the epoxy used to apply it? I am under the assumption that it needs the high temp to achieve its strength and stiffness.

What you are describing is called tempering, and the type of epoxy used will alter the outcome. Most epoxies you'd buy commercially are more than strong enough for reinforcing a stock, so you really don't need to go to extremes like used in autoclave cures.

If you cure a project at say, garage temperatures in the 40's, the strength of most epoxies you'd use would be quite low. In addition, if you put the finished product in the trunk of your car and temps raised much higher, the epoxy matrix will soften and re-harden to that higher temperature. If the item is under a load, it will deform and then re harden, and in doing so relax the load. That might not be advantageous. Which is why I employ a hot box to cure my projects. 170 F is easily attainable with a simple hair dryer or two. Just make sure you put a hot air exit port on your hot box or you'll melt your hairdryer. Don't ask me how I know...LOL

 

[Seagull]

Have used it in between laminates in hand grips and barrel channels . It can add strength were needed without adding much weight to the stock.

 

[rickiesrevenge]

What you are describing is called tempering, and the type of epoxy used will alter the outcome. Most epoxies you'd buy commercially are more than strong enough for reinforcing a stock, so you really don't need to go to extremes like used in autoclave cures.

If you cure a project at say, garage temperatures in the 40's, the strength of most epoxies you'd use would be quite low. In addition, if you put the finished product in the trunk of your car and temps raised much higher, the epoxy matrix will soften and re-harden to that higher temperature. If the item is under a load, it will deform and then re harden, and in doing so relax the load. That might not be advantageous. Which is why I employ a hot box to cure my projects. 170 F is easily attainable with a simple hair dryer or two. Just make sure you put a hot air exit port on your hot box or you'll melt your hairdryer. Don't ask me how I know...LOL

What kind of epoxy do you use?

 

[Texas10]

While there are many, I prefer the ones that have a 7 to 3 ratio. These are all based upon the same Shell Epon resin systems and are fairly tolerant of mix ratio errors, have good curing qualities when using heat, i.e. not a lot of gassing off, good shear strength and long cure times at room temps. This gives more open working time and the ability to push cure the resin with moderate heat.

Many of the tricks to working with epoxies relate to only waiting until the resin is set, but not cured hard, to perform mold separation steps, trim excessive materials, solvent clean surfaces, etc. These tricks can greatly cut time spent on a complex project. For instance, I can complete an action bedding project using Devcon 10110 filled resin in about 2 hours, start to finish without deviating from optimum mix ratios of the resin and hardener which by the way, you should never do with epoxies.

 

[Rat Rifle]

MClark, is that a full barrel bed Your showing in post #5 ?

Thanks...RR

 

[MClark]

Yes, full length bed.
This rifle has the stock attached to the barrel at the muzzle. The stock wood is pecan.
On another it looks similar but the barrel (17”) had a few layers of aluminum tape when done and is really free floated.

 

[Bc'z]

Yes, full length bed.
This rifle has the stock attached to the barrel at the muzzle. The stock wood is pecan.
On another it looks similar but the barrel (17”) had a few layers of aluminum tape when done and is really free floated.

I'd love to see some of your work compleated!

While there are many, I prefer the ones that have a 7 to 3 ratio. These are all based upon the same Shell Epon resin systems and are fairly tolerant of mix ratio errors, have good curing qualities when using heat, i.e. not a lot of gassing off, good shear strength and long cure times at room temps. This gives more open working time and the ability to push cure the resin with moderate heat.

Many of the tricks to working with epoxies relate to only waiting until the resin is set, but not cured hard, to perform mold separation steps, trim excessive materials, solvent clean surfaces, etc. These tricks can greatly cut time spent on a complex project. For instance, I can complete an action bedding project using Devcon 10110 filled resin in about 2 hours, start to finish without deviating from optimum mix ratios of the resin and hardener which by the way, you should never do with epoxies.

 

[MClark]

Here is a picture of the above rifle with carbon bedding.
Guns I make for myself are usually combined ideas I have floating in my head. Sometimes come out as more of a prototype than what some would call a "Fine Rifle".
This one I wanted the stock to be of woods found in the area of Central Texas where I hunt. The primary wood is Pecan with accents of mesquite. The mesquite was cut from a tree directly in front of one of the blinds. The layer of mesquite at the butt is not to make the pull longer, it is because Pecan is not the best wood and it is to prevent the butt from chipping if dropped.
Cartridge is 250-3000 Savage because I wanted one.
Action a Remington 700 single shot. While hunting we are forever in and out of vehicles and loading and unloading the rifle. With a single shot it’s easier to just drop cartridge into shirt pocket then to mess with the magazine. I have three hunting rifles with this action.
Accuracy (since this is the Accurate Shooter forum) with skinny barrel and the fore end attached to muzzle is a bit over 1” for three shots, if I wait till everything cools between shots it’s about 3/4”. As one would expect it has vertical stringing.
I typically hunt under 50 yards, if I’m going to have a long shot I have other rifles.
I have other odd rifle I have made.