Machining Carbon fiber sheet tips?

[klabeaume]

What is the best way to hold the material, adhesive sheets?
Any particular brand?
Rpm and feeds?
Type of cutter?

Any help is appreciated. Thanks

[skin6061]

How thick is the material? If it's only a couply ply thick then you can get away with a dremel and a cut off wheel. And the sanding discs to clean up the edges. As far as holding the material, I just hold it in my hand to cut what i need, i suggest gloves, carbon splinters suck. If you need any help let me know. Ive been working with carbon fiber/ fiberglass for the last ten yrs

[klabeaume]

I have a cnc mill so I am looking for a way to hold down some .062" material.

[skin6061]

Ok i can help there but not much since I haven't done alot of milling with carbon fiber. Hold it down like you would hold any other material down, just be carefull about how tight you torque it down. To tight and you can splinter the material. Basically you want just want it snug. If you can place something in between the clamps and the material that would be best. A piece of rubber is what i have found works best. Now when it comes to speed i have found the faster the better, kinda like making finishing passes of alum parts. Take small amounts off at a time, but this will depend on how tightly compact the material is so you might have to experiment here. I say no more than 10,000 at a time. As for the bit no course bits, this will cause splintering and could catch and break the part. A fine bit if best or a diamond grit bit.

There are few companies out there that are starting to make specialty bits for composite work in the automotive and aircraft company so you can check them out but i bet there pretty pricey.

When It comes to machining composites it's fairly new, so alot of people are still doing r-d for what works best for them. It took us about 3 months to perfect cutting carbon and fiberglass boards on a wet jet.

I hope that helps or at least give you a good starting point to work off. I would like to see what you have built of plan to build with the material. Like i said i have been doing this for ten yrs and love to see new projects. I once tried to build a nitro head for my rc10 6 yrs back. It was a disaster but fun

[BigSki]

One of the most important things about working with graphite ( cured carbon ) is to WEAR A RESPIRATOR, DO NOT BREATH IN THE DUST. The dust is a carcinogen, it is very nasty stuff.

[skin6061]

Originally Posted by BigSki

One of the most important things about working with graphite ( cured carbon ) is to WEAR A RESPIRATOR, DO NOT BREATH IN THE DUST. The dust is a carcinogen, it is very nasty stuff.

Yes that is very true, even worse if your allergic to it. Plain carbon with out the resin will make make most people itch, and sometime people will break out in little hives. Nothing to serious though. But what can turn serious is being allergic to the resin that the company used to make the laminate, i have seen everything from simple red itchy skin like a rash to severe allergic reaction where they stopped breathing. The thing is there are 1000's of different resin formulas out there, you may not be allergic to the one but you may be allergic to others. You just don't know till you start working with it. Not to scare you off or anything just warning you of the potential problems.

[rlockwood]

if it's sheet, use double stick tape, with as much surface area add you can.

[Crawling Calvin]

I know this is for after but putting thin CA glue on the edges is really smart. I broke the edges on some CF parts with like 1,000 grit sand paper WET sanding and it did good. Let the parts dry and put thin CA glue on the edges with a Q-tip.

I have cut my CF (with proper breathing protection on!) under a "water mist" and that did a good job of keeping the tool cooled down and the dust down. I used "Double cut carbide burrs" from McMaster carr. $5 a pop and they didn't last more than 1-2 parts before dulling but they got the job done for way cheap.

I know like Harvey Tool sells tools for composites in an old catalog I got from them

[SMR 510RR]

As far as tooling I would think something like a 6 flute EM would probably be the best, should help keep chipping to a minimum while you cut it.

Definitely stick it down with double stick, just make sure you cut the face of the plate you are sticking it to so it is flat. I got some double stick a couple years ago from mcmaster and stuff was so strong I had to hit it with some alcohol to get it to release the part.

[bigstu]

Has anyone used a vacuum table when machining carbon fiber?
My aunt's husband purchased a 4' X 8' CNC router table years ago. I helped him learn 3d Autocad to generate the tool paths he needed to run the monster. I asked him how he was going to hold down the laminated MDF panels, for making presentation podiums, cabnets, etc, and he said he was going to build a vacuum table. The table would be set up so the top could be repalced whenever it needed and used a small vacuum pump to hold the material down.
Has been in the back of my mind for cutting lexan and delrin sheets, so why not carbon fiber?
Something small that would hold something just big enough to make carbon wheels maybe?

I was also thinking that a shop vac with a REALLY good filter and a dust mask were going to be a must.

[rlockwood]

vacuum tables work great in some scenarios, but they're relatively expensive and require somewhat dedicated fixtures.. the vacuum plate needs to seal without leaking, so the ports all need to fall under finished material. Its also very surface area dependent.. and compared to the cost of double sticky tape..... but it certainly has its place-- they're not too intricate to DIY on a small scale either. For most people with a desktop mill, it probably isn't cost effective

[binaryterror]

Originally Posted by Crawling Calvin

I know this is for after but putting thin CA glue on the edges is really smart. I broke the edges on some CF parts with like 1,000 grit sand paper WET sanding and it did good. Let the parts dry and put thin CA glue on the edges with a Q-tip.

Depending on the material grade you use this is almost a non-issue anymore. Even many of the on-road and oval guys running CF chassis are now skipping this step.

Never a bad idea though. Also instead of CA, clear nail polish from your wife/gf used to be a trick back in the day as it drys a touch slower and yields the same results.

[klabeaume]

My main concern is holding it down, I heard people say they use an adhesive transfer but I am unsure what I need.

[BTF]

Originally Posted by klabeaume

My main concern is holding it down, I heard people say they use an adhesive transfer but I am unsure what I need.

give me a call i can help.

[JohnRobHolmes]

I use the force of sheer willpower!

[klabeaume]

Originally Posted by JohnRobHolmes

I use the force of sheer willpower!

Can you box some of that up and send it too me?

[jdobb]

where do you buy your carbon fibre sheets from. looking to get some. Thanks

[Stealthshooter]

I use my Vacuum table and a down cut bit to cut my composites.

[billet works]

I use an mdf fixture that the cf is bolted to in strategic locations to hold on to it. I've been cutting with 093 carbide 2 frlute end mills and they last a long time...but I need to track down some descent down bits for more new production cf work now

[Bad Attitude]

Originally Posted by billet works

I use an mdf fixture that the cf is bolted to in strategic locations to hold on to it. I've been cutting with 093 carbide 2 frlute end mills and they last a long time...but I need to track down some descent down bits for more new production cf work now

Onsrud makes some really good down flute endmills.