I need some help in properly grinding a tool for a spherical ball turner. The tool holder for the ball turner is angled at 7°. It can accept a .250" round bit. It's a Hemingway kits spherical turning tool so it sits tool post holder and the bit goes up and over the piece from the back to the front side.
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Grinding a Cutting Tool for Ball Turner
- Thread starter ddickey
- Start date
- Joined
- Nov 5, 2016
- Messages
- 1,419
If the tool holder is like the one I made (see my recent post) you shouldn't need any front clearance because the tool bit is at 7 degrees (I made mine 10 degrees) and that should be all the clearance you need. Make sure the tool isn't over (to far above) center. Treat it just like you would any HSS cutting tool that was cutting in the conventional position. You're doing the very same operation, just rotated up 90 degrees. On the top of the tool (end) I put a small amount of positive rake, maybe 10-15 degrees or so. Again, treat it just like you were turning a piece of stock in the conventional position.
That should give you a starting point. If you get chatter, you might want to have less rake or possibly even more rake. It's pretty much trial and error and YMMV depending on how rigid your setup and tooling are.
Good luck,
Ted