How small is small?

[Halfnutz]

Ive been experimenting lately with my MiniMill and trying to engrave as small as possible. I'm trying to determine the best cutting tools for this small stuff, and would like to see what other people are doing, what accuracies they achieve, and what they are using for machine and tooling.

[wjfiles]

I am waiting for info on this subject, one of my suppliers does very smalll letterig and swears by D-bit geometry. He has recently bought a D-bit grinder just for this type of work. I have searched for info on sharpening D-bits but so far zilch.

Bfiles

[Halfnutz]

Do you mean drill bits? I have heard about using old drill bits and re grinding them, but in a different shape than a drill bit. Ive used drill bits in place of end mills in plastic and MDF, with mixed results.

[ger21]

Try this site for engraving tools:
http://www.antaresinc.net/

[Halfnutz]

OK, so " D bits " refers to the cross profile of the cutter. Basically a piece of round tool steel or carbide with a little less than half ground away, and one side sharpened. Here is directions for making one from majosoft, a great DIY engraving site.

http://www.majosoft.com/engraving/

look for "making a cutter from an old drill bit".

[sanddrag]

A machinist I know just uses a center drill. Works well.

[Geof]

Originally Posted by sanddrag A machinist I know just uses a center drill. Works well.

Do they use a center drill or a spot drill? Center drills that have the small diameter pilot followed by a 60 degree taper out to a larger diameter are not suitable for engraving because the web is too thick and the end is ground to something like a 118 degree included angle. Small, 1/4" and 1/8", 90 degree carbide spot drills will do very nice engraving down to a letter height of around 0.10".

[sanddrag]

Just a plain ol center drill. Goes in .010 or so and it comes out beautifully. Very smooth.

[wholepair]

I use these for engraving.

http://www.micro100.com/inch/rtc_two_end.html

[2muchstuff]

Check with a dental supply, they can set you up with all different shapes and sizes of carbide and diamond burrs. They have a 1/16" shank and are inexpensive. I use them in my Dremel tool.

[Halfnutz]

I have a bunch of 1/8" drill bits I use, they're OK, but I'd like to try some of those engravers points from micro100. Its really small text that gets interesting, having a small enough tip and sharp point without digging in.

[Bubbles]

we use broken cutters. we grind them down on a small bench grinder, sharpening the bit at 15 degrees, rotating the bit untill all sides have been ground. We put 1 flute on the cutter and clear the back edge.. works pretty well. I can take a photo of a cutter if u like...