Milling CF

[Chris*33]

Hello,

My question is not directly knife-making related, but the thread looks appropriate, let me know if this is not the place.
I am planning on making some folder accessories from CF (clips/backspacers/scales), but before spending my money on a mill bit and a steadier collet i would appreciate any input from experienced members.
My main goal here is to get the CF scales to the desired thickness, and not any fancy machining. After that, i will shape & finish the part using a small belt grinder, a dremel and hand tools.

I'll be using my bench drill (i know it's not the tool for the job, but let's leave this out for now as i can't afford a mill at the moment) which goes up to 2450 rpm.
Apparently, that's quite low for CF, but i've read that it should be enough if i'll be using a larger bit (0.4/0.5").

Also, do you think i could use a router with a carbide flash trim to get the CF to the shape of an existing scale?
In this case i would be using an actual router so no problem on the rpm, here. You think the CF would respond well to the carbide bit?


Any thoughts/suggestions on the processes i have described would be greatly appreciated!

 

[navman]

Sharp carbide is the ONLY way to go for carbon fiber. CF is very abrasive and will wear tooling quickly. Wear the proper PPE at all times while working CF (Full face mask would be best), long sleeves and disposable gloves.

HSS may work for one or two pieces, but will likely lead to a poor finish and tear out.

 

[Daniel Fairly Knives]

You can do it! CF is really easy to work with, just very dangerous (think asbestos level) and super hard on tooling. It grinds crazy fast with ceramic belts like butter, hand sanding also goes fast. I like to do my sanding in a bucket of water under the water.

No advice on the router, I use a few for making guitars and think they are sketchy. I think you would spend a lot of money on bits. It should be easy to run on a router table with a premade thick template to follow.

No tools and silly cheap budget? buy a drill press and 1x30 grinder... drill and shape, hand sand to finish. Use regular cobalt bits, for a little more maybe get a mini drill press for under 100 as they run really high rpm for cheap and are great for carbide which you will run on it. Running carbide with a lot of runout on a cheap press will just break bits.

Slightly better budget - get one of those 1018 mini cnc routers if you have time to mess with it, learn cad/cam. They are super fun and cheap.

 

[Chris*33]

Sharp carbide is the ONLY way to go for carbon fiber. CF is very abrasive and will wear tooling quickly. Wear the proper PPE at all times while working CF (Full face mask would be best), long sleeves and disposable gloves.

HSS may work for one or two pieces, but will likely lead to a poor finish and tear out.

The PPE guidelines are appreciated and will be strictly followed, i assure you! Do you think that the 2450rpm will be OK with a larger size bit, as i've described above?

You can do it! CF is really easy to work with, just very dangerous (think asbestos level) and super hard on tooling. It grinds crazy fast with ceramic belts like butter, hand sanding also goes fast. I like to do my sanding in a bucket of water under the water.

No advice on the router, I use a few for making guitars and think they are sketchy. I think you would spend a lot of money on bits. It should be easy to run on a router table with a premade thick template to follow.

No tools and silly cheap budget? buy a drill press and 1x30 grinder... drill and shape, hand sand to finish. Use regular cobalt bits, for a little more maybe get a mini drill press for under 100 as they run really high rpm for cheap and are great for carbide which you will run on it. Running carbide with a lot of runout on a cheap press will just break bits.

Slightly better budget - get one of those 1018 mini cnc routers if you have time to mess with it, learn cad/cam. They are super fun and cheap.

I appreciate the input, the underwater sanding should make it much safer i take it, since no dust will be be created to get airborne.

Two problems with buying machines for me: i live on a small island (Cyprus in the EU) where you can't really find machines like that -or any type of machines suitable for knife making such as belt grinders, disk sanders, drill mills, etc, so even if i buy something from within the EU the shipping is actually killing me (being an island i mean). I was lucky enough to find a local guy who made a homemade 2x60 belt grinder because he wanted to try to forge-weld steel, and after a knife or two he decided to sell it. So any purchases without trying it out first our out of the picture at this moment.

 

[JV Knives]

An added tip is to select an end mill designed for "composite" material. Google makes that easy to find. The design of the flutes and cutting edges are optimized for cutting composite plastics, such as carbon fiber. Don't worry too much about your spindle speed limitations as you can somewhat compensate by reducing your feed rates. (Speed + feed) / cutting edges = chip load. If you can hit close to the optimal chip load then the only thing that will be reduced by your spindle speed limitation is the time it takes to perform the cut.

Finally, if cost is a consideration (it always is), spend your money on the right breathing PPE. As others have said, carbon fiber is no joke and the dust will do short and long term damage. You don't want lungs full of that crud or you will have a bad few days to remind you not to do it again. Good luck!

 

[Chris*33]

An added tip is to select an end mill designed for "composite" material. Google makes that easy to find. The design of the flutes and cutting edges are optimized for cutting composite plastics, such as carbon fiber. Don't worry too much about your spindle speed limitations as you can somewhat compensate by reducing your feed rates. (Speed + feed) / cutting edges = chip load. If you can hit close to the optimal chip load then the only thing that will be reduced by your spindle speed limitation is the time it takes to perform the cut.

Finally, if cost is a consideration (it always is), spend your money on the right breathing PPE. As others have said, carbon fiber is no joke and the dust will do short and long term damage. You don't want lungs full of that crud or you will have a bad few days to remind you not to do it again. Good luck!

Appreciated!

 

[navman]

not really the speed that I would be worried about, more the rigidity of the overall set-up. The reason a mill is recommended is because the colum/quill is more rigid and can stand up to side load required for milling. While it may not be an issue in a "softer" material like CF, it may lead to some destroyed projects because of chatter, flexing , etc. When machining materials speeds are a part of the equation, FEED rate is the other.

edit: just saw JV addressed it.

 

[Chris*33]

not really the speed that I would be worried about, more the rigidity of the overall set-up. The reason a mill is recommended is because the colum/quill is more rigid and can stand up to side load required for milling. While it may not be an issue in a "softer" material like CF, it may lead to some destroyed projects because of chatter, flexing , etc. When machining materials speeds are a part of the equation, FEED rate is the other.

edit: just saw JV addressed it.

I agree with you but no other option at the moment. I'll experiment on scrap pieces from hard wood laminates/G10/ micarta whatever i can find to see if it can be done smoothly (as possible..) and find the appropriate feed rate, then.
Thank you for your input navman

 

[navman]

Just food for thought: I started with a bench-top mill/drill from Sieg (many of them are rebranded as Grizzly, HF, LMS...) and it was perfectly adequate. I eventually sold it and bought a J-head Shop Fow, but that was more for gunsmithing.

 

[Chris*33]

Just food for thought: I started with a bench-top mill/drill from Sieg (many of them are rebranded as Grizzly, HF, LMS...) and it was perfectly adequate. I eventually sold it and bought a J-head Shop Fow, but that was more for gunsmithing.

Sieg is the brand that i've come across quite a few items as far as budget mill drills go, actually. They still start from 450 euros (510 USD) which is good for an entry level machine i guess, but still a considerable investment for the time being. If i do like the process and decide to take the next step i'll be getting a slightly better model from the get-go (still from sieg), maybe at 750USD more or less, since it would be more more stable, powerful, with a larger work area and also with a brushless motor, and most importantly, at that point i would really know that it will be an investment and not an experiment!