Carbon fiber stock build

JimmyO

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Dec 16, 2015
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Is the carbon fiber going to be exposed when finished?

I assume this is going to be a 2 piece mold. Do you plan to vacuum bag the two halves separately or do you have a plan that would enable you to do it as one piece?

If molding separately, how do you plan to join the two halves? I have watched a YouTube video where Sako uses a carbon fiber "sock" over a foam plug to make everything seemless. They then injection molded the entire sock covered foam "plug" in a mold.

I would think getting a pair of exact matching "halves" will be very difficult using hot glue. Instead of the hot glue to hold it in place, have you considered using threaded steel rods? I would think two rods screwed into the recoil pad mount holes and 1 into the forend tip would work perfect. Then when you are ready to mold the 2nd half you could just flip it over into the second mold. You would just need to make sure you pour your epoxy exactly half way each time.

Kudos to you for undertaking such an awesome project!
 

Tommo64

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Is the process similar to GRP, building up in layers of CF and resin? I assume that you will be filling your mold then shaping the finished stock as you would with timber, is that how it works? Pardon my ignorance on the subject.
 

Mram10us

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Rather than reply to each, here are the answers, gents.
1. The mold will be done in two halves. They will be done like mcmillan does in their video.
2. the hot glue is just a dab to hold the stock in place while pouring the epoxy resin around the stock.
3. to join the halves, the butt stock section of the the mold and where the barrel channel is will be removeable to allow me to put some cf and epoxy to attach the sides.
4. While in the mold, inner pressure will be added to the cf and epoxy with either a long air bladder or spray foam. Not sure what will work best

open to ideas :)
 

nksmfamjp

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Look up vacuum bagging and or hand layup videos. The vacuum bagging process has been successfully used to make professional composites in a home shop. It helps you get around the lack of a good mold.
 

Mram10us

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Look up vacuum bagging and or hand layup videos. The vacuum bagging process has been successfully used to make professional composites in a home shop. It helps you get around the lack of a good mold.
isnt making a mold easier then making multiple foam stocks to wrap and vacuum bag?
 

Tidus56

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We made a three piece mold. But we are using 3 d printed parts to hold the in letting so we can avoid having to do any CNC work. We also are making our inlet/chassis area out of compressed carbon fiber. Here is a foam with a CF chassis in it. We are doing hand layups not vacuum bagging. I wanted to learn how to vaccum bag just haven’t got to it. We designed the CF chassis to fit rem 700 SA. It works with my TL3 as well. Chassis weighs under 6 ounces and we have driven trucks over it. Total stock weight is 18.5 ounces without a butt pad. We still have refining to do to make it awesome lol.
 

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nksmfamjp

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isnt making a mold easier then making multiple foam stocks to wrap and vacuum bag?
Maybe I misunderstood. I thought you were doing 1/2 molds?

My thought was you would hand lay dipped sheets in the 1/2 mold, then bag it, then vacuum to draw air and excess epoxy out of the workpiece.

Letting the epoxy degas naturally doesn’t work very well in my experience...(limited)
 

JimmyO

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Vacuum bagging does not help you get around the lack of a good mold. What comes out of the mold is hopefully going to be an exact impression of the mold.

You vacuum bag the pieces while they are in the mold so that it draws out excess epoxy, it also helps eliminate voids in the epoxy. Ultimately, vacuum bagging is going to make a lighter and stronger product.

Carbon fiber derives a lot of it strength by being one continuous piece. If you are using a lot of pieces you will have to do multiple layers of cloth, which will add weight. I don't know how well it would work, but I would look at using carbon fiber sleeves in your mold somehow.
 

Mram10us

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We made a three piece mold. But we are using 3 d printed parts to hold the in letting so we can avoid having to do any CNC work. We also are making our inlet/chassis area out of compressed carbon fiber. Here is a foam with a CF chassis in it. We are doing hand layups not vacuum bagging. I wanted to learn how to vaccum bag just haven’t got to it. We designed the CF chassis to fit rem 700 SA. It works with my TL3 as well. Chassis weighs under 6 ounces and we have driven trucks over it. Total stock weight is 18.5 ounces without a butt pad. We still have refining to do to make it awesome lol.
Keep giving your input, brother! Good stuff.
 

Mram10us

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Maybe I misunderstood. I thought you were doing 1/2 molds?

My thought was you would hand lay dipped sheets in the 1/2 mold, then bag it, then vacuum to draw air and excess epoxy out of the workpiece.

Letting the epoxy degas naturally doesn’t work very well in my experience...(limited)
I plan and laying up the cf in each half mold, pressing together and adding a form of internal pressure. Think vacuum bag process from the inside. The stock will already be together when removed.
 

Mram10us

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Vacuum bagging does not help you get around the lack of a good mold. What comes out of the mold is hopefully going to be an exact impression of the mold.

You vacuum bag the pieces while they are in the mold so that it draws out excess epoxy, it also helps eliminate voids in the epoxy. Ultimately, vacuum bagging is going to make a lighter and stronger product.

Carbon fiber derives a lot of it strength by being one continuous piece. If you are using a lot of pieces you will have to do multiple layers of cloth, which will add weight. I don't know how well it would work, but I would look at using carbon fiber sleeves in your mold somehow.
This could be another option. If i cannot get the mold process down as planned, I can use the cf stock formed in the mold as a blank of sorts. Put a sleeve over it and vacuum bag . Hoping the internal pressure presses out any excess epoxy. I'm figuring out the epoxy thing a bit with the barrels and think there won't be much extra when laying up the stock. We'll see though :) anyone want to buy my first 4lb cf stock?
 

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