Kathy Marshall
03-27-2012, 1:46 AM
This is a step by step for turning a perfect sphere as demonstrated by Keith Gotschall.
The 1st step is to turn a blank to a cylinder. Start with a piece a little longer (about 1 - 1 1/2") than the diameter.
228105
After turning it round, measure the diameter with calipers (this will be the final diameter of the ball).
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Add about 1/32" to the diameter measurement. That will give you just enough extra to give a little fudge factor and still work with a jamb chuck. If you add too much, you'll have a hard time getting it to hold in the jamb chuck.
Take that measurement and transfer it to your cylinder, then find the exact center point and run a pencil line around the cylinder. Don't do what I did and scratch it in :eek: (really, I don't know what I was thinking, but at least I made it a very shallow scratch).
228107
Use a parting tool to define the ends, then start roughing out a sphere shape, being careful not to remove too much. I parted it down in stages so I'd have more support in the initial roughing. Part down the waste to a small enough diameter to be easily sawed off, but not so small that it will easily come apart before you're ready.
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Remove from the lathe and saw or cut off the waste.
Next you'll need to turn a jamb chuck. Turn a cylinder then mount in a chuck. Then turn a hole a little smaller that the diameter of the ball, it should be deep enough that the ball doesn't bottom out and the sides should taper in (ball shaped).
Continued.......
The 1st step is to turn a blank to a cylinder. Start with a piece a little longer (about 1 - 1 1/2") than the diameter.
228105
After turning it round, measure the diameter with calipers (this will be the final diameter of the ball).
228106
Add about 1/32" to the diameter measurement. That will give you just enough extra to give a little fudge factor and still work with a jamb chuck. If you add too much, you'll have a hard time getting it to hold in the jamb chuck.
Take that measurement and transfer it to your cylinder, then find the exact center point and run a pencil line around the cylinder. Don't do what I did and scratch it in :eek: (really, I don't know what I was thinking, but at least I made it a very shallow scratch).
228107
Use a parting tool to define the ends, then start roughing out a sphere shape, being careful not to remove too much. I parted it down in stages so I'd have more support in the initial roughing. Part down the waste to a small enough diameter to be easily sawed off, but not so small that it will easily come apart before you're ready.
228108228104
Remove from the lathe and saw or cut off the waste.
Next you'll need to turn a jamb chuck. Turn a cylinder then mount in a chuck. Then turn a hole a little smaller that the diameter of the ball, it should be deep enough that the ball doesn't bottom out and the sides should taper in (ball shaped).
Continued.......