Question: how to finish carbon fiber scales.

K

Ken Cox

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Greetings.

Over a year ago I started to make a knife almost entirely by hand.
I drew it with a CADD program and then had it cut out by water-jet.
From that point on, though, I have used only files and sheets of sand paper.

Since I chose BG-42 as my steel, I sent it to Thomas Haslinger for heat treatment in his vertical salt bath.
Now it has come back and I have spent many enjoyable hours polishing it.

My question involves the .25" thick carbon fiber scales I intend to put on it.
I had already had the scales cut to shape by water-jet and the pin holes drilled.
The time approaches when I will need to shape and finish them.

I had planned to use my files and various sandpapers for shaping the scales.
However, I have recently read some things that have me wondering about the safety of filing and sanding carbon fiber, as well as the effectiveness of these techniques.

Would someone please share their experience with shaping and finishing carbon fiber scales?
I want to stay with hand tools and I want to stay safe.

Thanks.
 
Ken, WHATEVER YOU DO, WEAR RUBBER GLOVES!!!! After I worked on my very first CF handle, I had the most aggravating rash develop in the webby parts where my fingers attach to my palm. The itching was so severe at one point, I though that scratching them with a fresh 60 grit on my sander would have felt like heaven. If it does that to toughened skin, imagine what it does to lung tissue so at least where a good respirator.

Hugh
 
Thanks, Hugh.

How does the carbon fiber respond to filing and sand papering?
What grits of paper did you use and at which stages?
Can I shape with sand paper or just finish with it?
 
Carbon Fiber is some seriously nasty crap, but its not very hard to work. It makes a mess, but works quickly with sand paper...
I dont have a problem with rashes, I dont wear gloves most times, but you can get these little slivers that will bug the hell out of you, and your hands will be blacker than a tire if you dont.
I sand mine up to about 400-600 grit starting with 120, and then buff on a hard buff, then a soft one with black magic. Heres what it looks like when done this way...
http://alpharubicon.com/~fixer/images/tracea.jpg
You can bead blast if for a textured feel but honestly I think it looks like crap, and G-10 would work better for that IMHO.
I would never try to shape it by hand with paper but I have lots of equipment. Figure out a way to shape most of it on some sort of machine, and then do final finish by hand.. Always wear a mask on this stuff.. Hope this helps ya..

Take Care
Trace Rinaldi
www.thrblades.com
 
After profiling on my grinder I've hand finished carbon fiber to 600 grit with good results. As far as hand shaping goes, files and sandpaper should work fine. Backing up the sandpaper with a small block levels out the surface. Wear a respirator and clean up good afterwards.
 
I wouldn't hesitate to use files and cloth-backed abrasives. Do the rough shaping with progressively finer files (bastard/second cut/smooth), then clamp the blade horizontally and use strips of shop roll to remove the file marks, using them like a shoe-shine cloth. Unless you have a buffer, I would quit at 400 grit for a nice matte finish.

DC_FxdBld-cfagent-501.jpg


This is one of mine rubbed out to 400 grit. Knife is 5" overall.
 
I would go real easy with files, unless you need to take alot off at once. CF sands real easy and comes off quick. There are different types of CF. I get mine from Les Halpern. I don't were gloves and have never had a problem. I do wear a resperator and have a vac system installed. I have never gotten a splinter from Les's CF. I however have gotten some aerospace CF that was a different type of weave and it felt like I was petting a porcupine when I was done grinding! ;) Different types out there and you will know what type you have real quick! :) I profile mine, slack belt with a Wilton square wheel. 80 then 120 grit. Then I go to hand sanding with 240/400/600. Then polish with green rough. If your looking for satin finish rather than polished, use Don's sugestion and go to 400 grit. Leaves a nice finish.
 
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