In a previous life I had to make cutters for cutting wooden parts in the piano industry, now don't just yawn and go back to sleep. Believe it or not these were precision parts. The maximum tolerance we were allowed on any part was plus or minus two thou and this was the blank cutoff.
Holes had to be bored to 1/2 a thou, all day, day in day out on tens of thousands of components.
Most of our cutters were shaped form tools not unlike involute cutters, with special shapes, serrations etc.
Most of the special ones were made from 2" blanks of oil hardening steel as this was all we could manage to work on site.
Previous attempts of having these cutters made out had turned out to be unsatisfactory in term of shape and tolerance and also very, very expensive.
So we blanked a soft cutter out , gashed it and finished it using a full sized 1" bore Eureka attachment. Then it came to hardening.
These were sent away to be professionally hardened and tempered at a local company who did a wonderful job, they came back with a completely even straw colour. We then ground the face gash up to get a sharp cutting edge and they went into service.
Although they started off cutting well even on wood which when you are using exotic species can be abrasive they never kept the edge and gradually got worse.
We eventually put this down to the fact that the grinding whilst being done dry like most T&C grinding operations was reducing the temper which isn't high to start with. So the next cutters were hardened only and the heat put into the cutter from grinding was the tempering operation.
These were quenched immediately from grinding and fitted to the machines.
This increased the life between regrinds considerably.
Now brass and alloy is not far removed from wood it terms of machinability so the same method will work on these materials and will increase cutter life.
