Engraving Advice Please!

[novacustard]

Hi.
I have been trying my hand at engraving, but without the success I had hoped for...I bought a half round cutter with 0.003" tip - one of these:
http://www.bitsbits.net/index.php?ma...ed0a0bfb982ae3

I used it in a Bosh Router at about 24000rpm, mounted to my CNC machine:
http://www.cnczone.com/forums/attach...9&d=1164274624

To cut this: (see attachment)


Cuts were 0.004" (0.1mm), down to a maximum of 0.02" (0.5mm), feed rate was 4.7 ipm (2mm/s). Material was 1mm thick sheet silver

The other attachments show a close up of the work and two chips in the tool.
I'm guessing that the tool got damaged at some point during the cut and then the damage contributed to the poor(!) finish...

I am at a bit of a loss really. I had previously cut two of these out, but was not really happy with the finish - The first I cut probably had a better finish of cut - I used a higher feed rate of around 12 ipm.
The other difference between 1 & 2 and no3 was that I was liberal with WD-40 and removing the swarf, whil I did neither for no.3

So is that it? I should have used lubricant and removed swarf?
What about the depth of cut and feed rate?

Any help gratefully received...


Richard.

[keneuro]

engraving silver, try cutting dry depending on silver, high speed steel d/bit or carbide spindle speed about 1800 rpm feed rate slow if letters are small . You should listen to sound of cutter as you are engraving then increas feed rate if sounds ok

[mc-motorsports]

Make sure your using Carbide. I didn't see where they stated what material that engraving tool was made out of. If the one you bought is HSS, no wonder your having problems.

Plus, that's a little expensive. You should be able to get those for half that price and made out of carbide.

MC

[keneuro]

your cutting edge is stuffed try sharpening at 40deg clearance then resharpen just the cutting egde at 32 deg clearence which will give you a stronger cutting edge with more clearence also slow your plunge into material