Gunsmithing wrapping with carbon fiber yarn

[GasLight]

Wondering if anyone has done any of this. I am particularly interested if there is a specific type of yarn that will enhance the thermal conductivity of the finished wrap, or if this is based in the wrapping technique and/or the type of epoxy used to bind the yarn? Also, does anyone know the best place to aquire carbon fiber yarn?

Thanks!

Dave

 

[gathert]

Re: wrapping with carbon fiber yarn

You can get a carbon fiber weave and sheets of fabric from some R/C plane companies. I've used some to strengthen the wings on m planes. Would be helpful if we knew what you were wanting to do specifically.

 

[GasLight]

Re: wrapping with carbon fiber yarn

I am wanting to wrap a tube with it.. heat transmission and lightweight are the draw to the carbon fiber.

Thanks

 

[former naval person]

Re: wrapping with carbon fiber yarn

Look in boat building sites...West Marine or Jamestown Supply both sell unidirectional carbon fiber for strengthening stuff. Look under "West System Products" for the book on usage and epoxies.

 

[JJones75]

Re: wrapping with carbon fiber yarn

I have a few miles worth of carbon fiber ribbon around here some place , let me see if i can find it and i'll donate to the cause

 

[gathert]

Re: wrapping with carbon fiber yarn

Fiber glass epoxy should work fine to harden up the carbon fiber. Mix it kind of thin and give it an even coat once you have wrapped the tube. Here is a link to some stuff, but by all means go for the free stuff.

http://www.fiberglasssupply.com/Product_...and_kevlar.html

 

[Shortdraw]

Re: wrapping with carbon fiber yarn

Carbon fabric is a whole different animal than the carbon thread used on the ABS barrels. Carbon fabric is a very effective insulator and is less than ideal for a rifle barrel used for other than hunting. Epoxies vary in price, characteristics, and uses. Carbon has many sizes, forms, grades, and uses so you can't just use what you have for structual stuff. You can do a carbon fabric or ribbon barrel yourself with a fiberglass epoxy resin but it won't provide you with the desired results. If you are going for an ABS style barrel, you will need to do a ton of testing and research to get the job done right. My best friends mother is the head of composites for a major aerospace company and my good friend is a composites pro with the USCG. I have picked their brains for projects for quite a few years so I have a bit of knowledge in the subject.

 

[turbo54]

Re: wrapping with carbon fiber yarn

The barrels I've seen done in CF did not have uni-directional thread wrapped around the barrel, at least not visually. It had about 3oz weave, running parallel/perpendicular to the bore.

If I were to do one, I would use uni (for hoop strength) on the inside and layers of weave 90 and 45 over that.

Also, don't even CONSIDER using dry CF and wetting out with resin. Don't even consider it. This is a prepreg only application.

 

[GasLight]

Re: wrapping with carbon fiber yarn

Yes, I definitely don't want to use fabric or sheet at all. Not what I am going for. I appreciate all the input, and I am definitely not trying to dig for some proprietary information here, I am just wanting a very general answer. I haven't seemed to get that just yet, so maybe I'll pose it a different way and can get a more definite answer:

Does the heat dissipation properties of a carbon wrapped barrel come from: (pick one or more of the following)

a. The heat dissipation property comes from a specific type of carbon fiber filament.

b. The head dissipation property comes from using a specific wrapping technique or pattern.

c. The heat dissipation property comes from using a specific type of epoxy or other bonding agent.

I am not wanting the cool look of the checker board or weave pattern of the carbon fiber sheet, I am looking only to reinforce a tube and I want it to have the lightweight and heat dissipation benefits that are similar to what ABS and others are using (not Christensen

)

Thanks again for any help or input.

Dave

 

[turbo54]

Re: wrapping with carbon fiber yarn

The answer is a combinatin of both b and c, but mostly c.

All materials have a coefficient of thermal conductivity.

Carbon has one
Each epoxy will have one, and they will differ

The thermal conductivity will therefore be a combination of which epoxy you choose, and the geometry/arrangement of carbon/epoxy you use.

Thermal energy (heat) moves (and its movement is resisted) through materials in the same way that electricy moves through a circuit.

For example, consider a very simple circuit with a source and a lightbulb (resistor). The electricity will flow very easily through the copper conductor, and then with difficulty through the filament of the light bulb, so that heat will build up and light will be given off.

Heat dissapation is a function of the thermal gradient, and the specific heat of the substances (we are not even getting into radiaton here, which is ok, as emissive power is a function of temperature to the 4th power....and we're talking about relatively low temps).

My suggestion: Pick the strongest prepreg you can, and let the thermal conductivity and heat dissapation chips fall where they may.

 

[bigsky23]

Re: wrapping with carbon fiber yarn

These guys sell kits for any application with fantastically strong epoxies. I've used them on carbon and stainless pipe.


http://www.cittech.com/prddiamondwraphp.html

 

[bigsky23]

Re: wrapping with carbon fiber yarn

These specific epoxies work very well.

http://www.cittech.com/prddwspecialties.html

 

[ejg]

Re: wrapping with carbon fiber yarn

I would approach in the following manner.
With every lay up of fibers one has small inbetweens where there is only resin. To generally improve the heat transfer through the resin I would add a small ammount of aluminium powder (ex. 45 micron) to the resin. The ammount must be judged in such a way the the overall volume will not increase because of the viscosity change.
Resin, I would choose a possibly thin flowing laminating resin with a long pot life and that has a temper profile that you can achive. (sometimes laying a epoxy piece on the dash inside the car can provide enough heat in the summer if one doesn't have an oven.)Aerospace approved resins are mostly very good, I wouldn't use any other.
Fiber, depending on the load that you will have on the part one can use more of one than the other.
I would use one or more layers of woven carbon tubes. These tighten nicely when pulled at the ends.

Then wrap carbon rovings around also to compress and squeeze excess resin out. The higher your carbon content vs thickness is, the better your heat conductivity.

edi

 

[Cegorach]

Re: wrapping with carbon fiber yarn

http://www.6mmbr.com/gunweek092.html

There is some information near the bottom of this page that talks a little about process and application.

 

[TOPO-sniper]

Re: wrapping with carbon fiber yarn

If you want a shooter buy a barrel already professionally done. One of the qualities of CF is the ability to custom tune the bending characteristics of the structure (tube). The mechanics of composite materials are graduate level engineering, fiber to matrix ratios and how they're laid up matters. Without a high temp/pressure lay up you will probably fracture off the matrix, you may see it and you may not (voids between the barrel and the composite). Definite possibility that the POI could change on the barrel as you put it through heating cycles. YMMV

 

[WhiteDingo]

Re: wrapping with carbon fiber yarn

So everyone assumes that's it's a barrel you want to wrap, but all you've said so far is "tube". If I may ask, GasLight, what exactly are you going to be wrapping?

 

[turbo54]

Re: wrapping with carbon fiber yarn

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TOPO-sniper</div><div class="ubbcode-body">If you want a shooter buy a barrel already professionally done. One of the qualities of CF is the ability to custom tune the bending characteristics of the structure (tube). The mechanics of composite materials are graduate level engineering, fiber to matrix ratios and how they're laid up matters. Without a high temp/pressure lay up you will probably fracture off the matrix, you may see it and you may not (voids between the barrel and the composite). Definite possibility that the POI could change on the barrel as you put it through heating cycles. YMMV </div></div>

This!

THIS PROJECT REQUIRES PREPREG CF AND AN AUTOCLAVE. DO NOT DO A WET LAYUP.

 

[E. Bryant]

Re: wrapping with carbon fiber yarn

Unless you are substantially increasing the barrel diameter (and thus the surface area), don't expect any significant change in thermal performance. Transferring heat to still air via conduction is an inefficient process, and is only minimally affected by material properties (conducting heat from a point source is different, and is an application that requires good material selection).

 

[puddlejumper]

Re: wrapping with carbon fiber yarn

You might want to consider that steel, be it stainless or chrome molly will expand and contract from heat at a different rate than the carbon fiber will. I have done a couple tensioned barrels with a carbon tube. They perform very well, do a great job of elimiating some of the harmonics and don't rely on a bond between the barrel and the carbon. Use a muzzle break with a shoulder turned on it to tension the barrel between the carbon and the action face.