Re: [CAD_CAM_EDM_DRO] more on broken taps

Marcus & Eva wrote:

> What is your source, and how are they described in the catalog?

What I've used are custom ground from round. I do have a Cuttermaster
and can grind my own, also have access to a Deckel single lip cutter
grinder. MSC calls them "split end blanks. I usually just grind the
split myself.
I grind to a dia just under tap drill as previously mentioned.
A few degrees of side clearance is ground and releived all the way
around, even though the tool cuts only on the bottom.
Bottom back clearance is ground to about 5 degrees, with a flat bottom.
At this angle, if you rotate the tool a few degrees and take a pass, and
continue until you have reached the other side of the tool, you will
have a flat bottom tool that cuts to center.
I don't make the split any deeper than needed, to increase rigidity.
This will NOT drill like a normal drill, you are taking a series of
spot-face cuts as you work your way through the tap. I did take out a #4
once with the cutter in a 1/2" Albrecht chuck, but I really recommend
using a collet. I've drilled out #4 through #10 taps this way. I'd post
a pic, but don't have any at the moment. Since I can make these as I
need them, all the ones I have made have since been reground into boring
bars or other custom tools.

Jon