[poster]

I am trying to grind some countersinks (more of a small relief approx. 1/16" deep) on top of some 1/4" holes in a very hard material. I have tried every insert known to man, carbide spot drills and carbide countersinks multi flute and single, single and double cut. Some of these have worked but it is slow and tool life isn't long enough to complete one part. I would like to try grinding them with maybe a diamond grit countersink, but am having trouble finding them. Does anyone know a supplier that may carry something like this? angle is 90 degrees, shank size can be up to1"

[KilrB]

1. You say you are trying to grind a c'sink, then list a variety of carbide tools you have tried to use. Which is it ... grind or cut?

2. You say the material is "very hard". How hard is it?

3. What machine are you trying to do this in?

4. 1/16" is going to be a long way to lap.

Unless you have hard-milling capability your best bet sounds like it's going to be sending it to someone who does, or has a sinker-edm.

[ERUS]

I would try one of these. - Harvey Tool - CBN Miniature End Mills - Ball

Its a CBN ball endmill. You might be able to use a surface toolpath with the CBN ball.