Moulds/Carbon Fiber/Custom Stocks

[hueyville]

Over the years I have purchased quite a few custom stocks for project rifles. Some have been good, some bad and some great. But none have been perfect. I have tried adjustable stocks but they tend to be heavy and unattractive. A month ago or so started going through the vaults and pulled the five or six rifles with my favorite stocks. Some I like certain features, others its fit and some styling. I took the actions out of them and carefully photographed in four different axis and took every measurement I could.

I imported all of the photos into my.favorite 3D CAD program, sized them properly to the actual stocks and rendered each into full 3D models. Once this was done I started overlaying them on each other and combining the features I wanted and dimensions of best fitting. After a full day I ended up with a fully rotateable model of what I want to try for a stock on my next build. So now I have it in SolidWorks and no matter how I spin it all looks good.

All I have to do now is render it into G code for the CNC machine to make a mould. I met with my carbon guy to see how he wanted it split into the A and B mould and tolerances, etc. I thought I was done. Now he wants to know if want to use wet process or dry process carbon. Dry process you put the carbon in the mould the using a vacuum you pull the resin through the carbon fiber. With wet process you put carbon that is already impregnated with resin and then use positive pressure I believe to activate the resin.

According to wet or dry there are some different things I have to do to machine the mould. Any of you guys ever made a carbon fiber stock and if so, which process and why. My guy says each has pros and cons. He says wet is easier but dry looks nicer. So what gives? This is new territory for me and going to be a huge investment of time and money. I can't seem to find any info on which others use and why. Thanx for any help.

 

[esheato]

Totally cool thread.

While I have no knowledge about CF, I find this topic and your ambition and skills admirable.

Please keep us updated.

Ed

 

[Big Boy]

any way we could see the rendering?

 

[hueyville]

The modeling is done, the code rendered, simulation run to verify no tool collisions , etc. Now just to decide wet or dry carbon technique as there has to be a little different configuration of mould according to which one I decide to try. If.it works, then I can spit.out a new stock every time I can talk the wife into a new action and barrel blank. Someone seems to have a firm opinion with reasons in all the other topics so hoping to find someone with carbon stock knowledge and how to best lay carbon for them.

 

[taliv]

i did get to tour tom manner's "factory". very interesting look at how manners stocks are made. sadly it didn't make me an expert and i don't have any advice for you. hopefully someone will

 

[Greenmachin3]

I've done both wet and dry lay ups for motorsport applications.

Dry (pre-preg or pre-impregnated with resin) is better if you have an autoclave to put the vacuum bags in. It's much less messy, and much easier to cut into the shapes that you need for the lay up if you have an automated laser cutting table. They also typically come with a peel-ply so putting on the different sections is almost like putting together a layered jigsaw of band-aids.

If you don't have an autoclave and only have a vacuum system, then wet (you mix the resin/epoxy and paint, roll and press it into the weave) is the way to go in my opinion. The best advice I can give you if you are doing wet layups is go a little heavy on the vacuum pressure instead of light and make sure you get all of the air bubles out. Also, go with a slower acting hardener at first until you get your lay-up process down, you'll want time on your side. There's no worse feeling than to pull a cured layup from a mold to find small bubbles in the CF on side that shows. They're kind of like fish-eyes in the clear coat on a car, except they're full of release agent so they tend to look like little white dots.

There are several different sizes, 3k all the way up to 24k threads per strand in the weave. There are also many different weaves, spread tow, tri-axial braid, V weave, harness, "regular", twill, and other applications specific weaves. All have different uses for different strengths, weight, and contouring ability. The larger the size,the harder it is to contour around tight radii.

Most people cover the part (put down as the first layer) in one lage part covering piece of small weave so it will have the CF look while not looking puzzled together and only having one seam.

If you want, I can PM you a cutaway of a CF push-rod we did for some race cars a few years ago so you can see how we used different weaves next to each other for strength and can explain some of the techniques.

 

[hueyville]

Greenemachine, yes would like to see. I want the stock to look slick. If possible like there is not a single seam. As to equipment, my vendor has the correct equipment do it right. He just advised I get some info from someone on which is best for a rifle stock. He mostly does car and motorcycle parts. Want to leave enough bedding area that if pleased, can put a variety of actions in same design without cutting fresh moulds. If it works, will hook up my friends. My plan is to buy some 30 cal match rifle blanks and 3 reamers. Then I have a new hobby as my back is slowly rotting away.

 

[Greenmachin3]

PM sent

 

[rodensouth]

That sounds like a stellar idea. I can't wait to see the outcome, but I'm too ignorant to offer input!