Engraving hard plastic

[nosplinters]

Hi all,

I'm attempting to engrave on a Swiss army knife and I'm not getting very good results.

I'm using a 60 degree cutter bit; however, I'm not getting a clean cut. I'm running the spindle at around 4K RPM. Should I be running max (10K RPM) for engraving hard plastic or do I need a different type of bit?

I want to ask before I screw up another knife.

What type of bit should I use to engrave onto Stainless steel as well (Diamond dragging?).

Thanks!
-Ed

[stratcat50]

I've not had much luck with those 60 deg. cutters in plastic.
Onsrud (www.onsrud.com) make a 0-Flute engraving cutter that seems to
be the ideal thing. I've got one ordered for engraving acrylic & polycarb.
I can't get my P/C 7310 router down to a plastic-friendly speed even running
on a Variac outputting 30 Volts (7500 RPM). Below that, it has no torque.

I get good results with a 2 flute upcutter but it's 1/8" diameter.
Too big for pretty stuff but cuts very clean.

Emory