Composit stock help? Fiberglass and Carbon fiber

[coyotehunter]

I'm wanting to build a fiberglass/carbonfiber stock using the Whidden Gunworks bedding block. Anyone build a composite stock? I would appreciate any help I can get not much online.

 

[BoydAllen]

To do it right will take a larger investment than any potential savings, and be more involved than you might imagine. If you just want a stock with a built in block, check out the Manners Stock website. http://mannersstocks.com/

 

[coyotehunter]

I want the personal satisfaction of building one like doing things myself. I was just trying to see if anyone had any pointers. I can get the whidden block for 109 and figured I would go from there.

 

[Hamo]

I have done it... a couple of different ways.

1) (easiest and cheapest)
get some Balsa wood or closed cell foam (divinycell is best, should be able to get if from a fibreglass supply place).

carve/build the stock you want, perhapse about 1mm smaller (as you will be covering it in carbon/glass).

cover the stock in at least 5 layers of 200gsm cloth, think thats about 8oz but its all metric over here. Use woven cloth as chop strand is messier, and unless you are really experienced will give a really bad finish. I suggest you take your time and do no more than 3 layers at a time, unless your really confident. Mask off all the other areas (eg, if your doing one side at a time) so you dont dribble resin everywhere. I would suggest that you use at least 15 layers around the action. The way i do it is i cover the action in release wax, and cover any holes in masking tape. I then build up layer after layer over the action building an upside down U shape. If you go to far you will lock the action in there forever. After 10 or so layers let it cure. If you want more strength (suggested) i would put a few more layers on it. This will be your 'bedding block', trim it to shape

cut a hole in the balsa/foam with generous space for your bedding block. and put LOTS and LOTS of carbon around it. (10 ish layers). Once its cured, line up the block in the carbon fibred hole and epoxy it all together.

Its a cheap way to make a good stock, but you do have alot more finishing etc this way, and the weight of the balsa. Note: balsa tends to drink resin, so do a thin coat of it and let cure before you glass the stock so the resin doesnt get sucked out of the mat.


2) The hard way: molding it

Essentially, i would make a stock blank exactly as the previous method stated, or find a stock that you like and want to copy. If its for a mold, it doesnt need to look pretty, or weigh anything etc. its just for shape. Use car filler to fill holes etc till your stock is exactly the way you want it.

to make a mold requires some thought. The ones ive seen for a rifle stock are 3 piece. One above for the barrel channel and bedding, then one for each side. they all sort of bolt together to create an internal mold.

the easiest way is probably to make 2 sides, then cut the barrel channel and inlet for the action. If your using an alloy bedding block, and the stock is hollow, it should be easy to wedge it in.

to make the mold, i would suggest cutting a piece of perspex so that the blank fits snuggly in the middle of it, so theres half sticking out one side. Fill in any gaps with modelling clay as smoothly as possible.

RELEASE WAX. Lots of it. Add more. pollish, more wax. i cant say this enough.

put a layer of gellcoat down, and about 2 hours after cover it in chop strand so that its very rigid. probably around 2000gsm

after its cured, prey and hope that it pops off.

remove the perspex, and put the stock back in the mold. wax the stock and the completed mold half, and lay more gellcoat and glass on this. Take it off and you have a completed mold. (3 piece mold just do it again for the top)

IF you are good you can lay a complete stock in one go, or one per mold then join them together.

I would suggest using 5 layers of 200gsm bidirectional Carbon and 2 layers of unidirectional carbon 200gsm. Fibreglass i would use woven matt totalling 2000gsm


Just a side not, i have made about 6 molds so far, and am yet to have good success for a rifle stock... something always goes wrong.

GOOD LUCK.

Its a great project, but take your time and do it right. Dont forget rubber gloves, its messy stuff

 

[Tozguy]

If you have already worked with fiber reinforced resins then you must have an idea of what you are getting into. If not, you may want to visit a place that does that kind work and size it up. Knowing where to buy the right materials is a challenge in itself. If you plan to use ordinary polyester resins as sold for auto body work, be aware that once the first application has cured a second layer might not stick too well to the first layer because of wax-like stuff that migrates to the surface. You are in for a great learning experience and I am sure you will get satisfaction from trying it.

 

[Hamo]

Theres different types of resin...

Laminating resin is used when its an inner layer... its designed to be sticky when you add more laminates on top.

Finishing resin is used for the final layer and resin does not stick as well to this.

Of course, Epoxy is my preferred choice. Its more expensive, but gives a harder and more durable finish. you don't need to worry about different resins for different laminates.