DIYbanter - View Single Post - Grinding a blank lathe tool for parting or cutoff

Al Patrick

wrote:
Ive used some 3/8 & 1/2 square tools that were factory ground to
about 1/16 on the end for parting
and cutoff. They work great but when I tried to reproduce one from a
blank, well the results werent very good and it takes forever to grind
away that much material. Has anyone ever ground there own ?

I knew a fellow who had to custom make some special shaped lathe bits for a factory. They
furnished some blanks which were close to what they wanted but needed modifying. What he
had to do was soften them up, grind them as desired and re-harden them. The "softening"
and the "hardening" is in the cooling process.

IIRC: A quick quince will harden them and a very slow cooling will soften them.

He used plain old lime like you use to alkalize your lawn to cool them very slowly. I
think he first got them cherry red and jambed them into the lime and left them half a day
or so to cool. I think water will make them too brittle. Oil may be what you need to get
it back to tool-hardened condition.

Don't hold me to the exact above, but that's roughly the process and I'm sure we have
several here who can tell you for sure!

Al