Setting up a ball turning attachment

[ml_woy]

Just finished building a ball turning attachment for my Craftsman 12" lathe. Now I need some help setting it up and thought that this forum was the perfect place to come to. If someone can go through the steps with me it would help.
1. center the tool height in the center of the diameter of the piece.
2. Using a 1" diameter piece of material,to make a 1" ball, should the tool post be set the distance of the radius of the ball from the center of the turning attachment?
3. Should the saddle be positioned the same radius distance along the side of the material being turned?
4. Should the tool rotate an equal distance to both sides of the diameter of the piece being turned to start with?
5. Does the diameter of the piece being turned have to be turned down to allow the tool post to clear when rotating the bit to the left when turning the left side of the ball?

First attempt to make a ball and concave cut turned out a 5 on a scale of 10. Tool cut great, but bottomed out against the left side of the material when trying to finish the ball radius. Concave cuts worked perfectly.

[f350ca]

With the one I had, I'd set up on the end of the stock, so that I could rotate the cutter front to back, adjusting the radius and in out position on the cross slide till i could touch the cutter on the front and back. This gave me the correct radius and final cross feed setting. Then swing the cutter to the middle and move the carriage till the cutter touched the end of the stock at the middle, now lock the carriage. Bring the cross feed out to clear the stock and start the lathe. Keep advancing the cross feed as you sweep the cutter from side to side. Initially your only cutting the ends, as you come in on the cross slide the cuts get longer till your touching all around the completed ball.
If the ball is integral to the shaft, yes you need to neck the stock down to the size you want the shaft before you turn the ball.
I found it easier to cut a piece of stock, drill and thread it then use a threaded arbour to turn the ball on, then thread the handle to take the ball.
These ones are threaded on to tapered shafts.



Its takes some playing the get the initial stock length right, its a little shorter than the diameter of the ball to alow for the lost curve where the shaft goes in, you can see some of these were too long and left a shoulder.



Hope this helps.

[rleete]

The key to getting a round ball is to have the center of rotation of the turning attachment right on center of the part in both directions. i.e. right along the axis of the turning, and halfway along the part (same as radius).

Adjust the tool as necessary.

[Arbalest]

This is my ball turner.



You will see there is a scribed line on the base. This denotes the axis of rotation. To turn a perfect ball this line is aligned with the axis or centre line of the lathe. I then adjust a backstop to prevent the cross slide from going past this point. The cross slide is then withdrawn to commence cutting. The other scribed line (on the turret) is used to set the diameter of the ball required - distance from this line to the cutting tool = the radius. The first (only so far!) ball I turned using this method is the one in the picture and is to all intents perfectly spherical apart from the collar.

[ml_woy]

Thanks guys for coming through with all of this help. I know now I can make the perfect ball with this information. I am going to add a scribe line to my base and tool post to help align the cutter.