Hi Thanks for the information, unfortunately i couldn't get any sensible numbers out of pilotltd I dont think its quite the right tool for the job.

Im going to try the Mega Electronics tool £10 each and if not there is a Bantum 0.003" engraving bit on Digikey for £30 each.

I tried these:
https://www.eternaltools.com/carbide-engraving-bits
30 degree 0.1mm, but again very poor cut quality.

Regards
Dom