Making a lathe tool

[JohnHaine]

I wouldn't try that if I were you - that's an awful lot of grinding! 3/4 sq HSS is tough stuff - and do you have the height to accomodate it?

Better would be to use a bit of thinner gauge plate or an old file - in the latter case get it red hot and keep it there for several minutes to soften. Then you could form the profile and harden. You might get away without to rake if you take it slow and use lots of coolant. Of improvise a kind of "inverse ball turning fixture" so you can use an ordinary turning tool and move through an arc.

Easiest if you have only one to do would be to form the curve by a series of small steps then smooth out with a half-round file.

[cropwell]

You are right about the piece of HSS, it is too thick to go in the tool holder, maybe only by a mm or 2, but that would mean a time on the surface grinder. It might be easier to get a smaller piece (1/2 x 3/4) or nearest metric equivalent.

I have an initial batch of 10 to make, and probably another 10 after that. I would like to get them all the same, so I thought a profile tool would be the easiest. The grinding facility I have is a wet linisher with 100mm x 3 metre belts. That is at a friends workshop, and he is retiring this year, so he isn't worried about the belts.

I have been meaning to make a ball turner for a couple of years now, I have the stock to do it, but not the impetus.