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RE: Form tools on an Atlas 12" lathe

Bruce:

I was fortunate to learn lathe work in the early '60's when most tooling was ground from HSS blanks and the experience I got then has been invaluable now that it's a hobby. The key is to keep the clearance and rake angles as well as the feeds and speeds for the various materials in mind no matter what tool you are grinding. The trickiest tools were usually the small boring or internal threading tools made from a 1/4" or 3/8" HSS blank that had to work inside a 1" diameter blind bore 1 1/2 inches deep. Still, the basics were the same. Keep practicing, keep making chips with offhand ground tools and you'll get really good at it.

I'm not a fan of using form tools on a light lathe like my Atlas 10". It's not a matter of the horsepower, but of the chatter and the possibility of hoggin in. One approach is to nibble away at the work, where a stronger lathe would allow a form tool plunge cut. Use a ball cutter where the tool is basically single point cutting, rather than try to form cut a 1 1/2" diameter sphere. If you don't have a ball cutter make a series of tangential cuts approximating a sphere, check the form with a radius gauge and finish it with a file and wet-or-dry paper. Do a deep cutoff by making several plunge cuts with a parting tool offset by 10 thou to provide plenty of side clearance for chips and lube. In other words, get inventive and have some fun figuring out how to overcome the limitations of your machine.

The pdf of the pulley groove turnng setup is a great example of how to use an inventive setup to solve a problem. Most of all, keep making chips and have fun.