Newbie + PCB + conical cutter = horror

[MGPL]

Hi,
I'm new to PCB milling.
I have a 0.1mm, 25° HSS three-sided precision CNC cutter, going 0.1mm deep,
F600, RPM:8000 and the tips keep breaking, where am I going wrong?

I'm starting to run out of drill bits and I don't want to keep breaking them,
has anyone done PCB cutting before with this kind of HSS 0.1mm tip tool before?

depth of cut, RPM, and feed rate would be much appreciated

[DSIF]

F600.0 IPM in fiberglass with a .2mm HSS cutter. ARE you kidding me? Fiberglass eats carbide up!

[MGPL]

Alright.. so is it doable at a super slow feed rate or with a tiny stepdown?
If not, what do i need? diamond?

[jeffrey001]

Have you checked spindle for run out.

Tu use such a small tip tool, you need to have absolutely no run out at all.

If feeding too fast, just the weight of the cnc milling head is enough to break the tip.

You need to have a pretty solid machine to run fast.

If spindle can rotate faster, try increasing RPM to at least 20000 to 25000.

Just a tough.

Jeff

[kn6za]

Definitely do what Jeff says. But keep in mind you are using HSS and that is not the proper tool selection for cutting circuit board material.

You need to get carbide tools to get a descent tool life.

I sell carbide tools at: www.drewtronics.net

Good luck

[MGPL]

thanks Drew, but I'm in China and the exchange is brutal I found some spade cutters like those you sell here in China.

I found a solution to the problem although I will look to get carbide for the future. Didn't try to push it further because I only had two drill bits left. The machine is mostly entirely made of PVC, so it's not the most sturdy of thing. Only needed to test out some schematics.

Solution for now
tool specs: 0.1mm tip, HSS spade cutter
copper line thickness: 0.5mm
material: PCB
Feed rate: F60
Plunge rate: F10
Stepdown: 0.0125mm each pass

[kn6za]

MPGL,
Glad you got if figured out.

Andrew