Cutting Carbon Tube in a Lathe

General Composites Discussions Composites Talk
#1

Hello,

I am using a 10mm carbon tube as a shaft inside a bearing. I have to sand down the OD of the shaft about 0.12mm to fit the bearing and also cut lots of little tubes to length. Currently I am cutting the tube with a fine tooth hacksaw and reducing the OD by sanding with 320 grit sandpaper. This seems to work fine, but I get a few small splinters where I pass through the far side of the tube. I think the tube is extruded because the splinters/fibres run parallel to the tube axis.

If I have to make a few more of these RC aircraft parts I’m thinking about getting a mini lathe to make the cutting easier/neater. Would a hacksaw still be the best way or would some sort of cutting bit be better? I’m thinking that hacksaw blade + lathe may be better because the cutting pressure will always be from the outside inwards. I’d have to be careful not to clamp the tube too tightly because the wall thickness is only 1mm. I know carbon dust is bad for electrical equipment.

Thanks.

Thanks.

#2

Definitely a rotary tool with a cutting wheel. It’s all about the speed, a cutting wheel you can use high rpm to cut it and you won’t get the splintering.

#3

Sounds like you have a pultruded tube where all fibre is longitudinal due to the manufacturing process. These can be prone to splitting depending on your application. Be careful clamping that with the jaws.

#4

pultruded, or normal wrapped tube, you want the strength to be along the length, so you will always have mostly 0 direction fibers. It’s a pain in the arse to cut. Try a cutting disc type of tool, and sand the ends well before you sand down the diameter you want. Maybe sand extra, and coat lightly with resin? Lathing CF is VERY VERY hard to do, and impossible with highly unidirectional parts.

#5

Dermal with a .5mm diamond disc tool in it. High rpm , cut like butter , never splinter , and never bite.
If you could mount the bearing , and then hold that in a jig or vise so you can spin the carbon tube would be best.
Also wrapping tube with masking tape helps a lot with splintering.

Tim

Who build rc gliders for a living :). ( gizmo 36 sloper)