Completed my ball turner...now how to use it?

[Threadkiller]

So I've been working on a ball turner for a while when time allows and I finally completed it yesterday. Its a typical design you see of ones that are already out there, I just copied the overall design but with all my own measurements. I had to make a special base for it since I have a South Bend 9A with the tapered mount. I wanted to make it out of steel but I had the right size aluminum in stock so I just made it all out of aluminum minus the part that does the actual cutting.

My question now is, what is the best way to use one of these? Do you zero the dials and adjust the turner to the desired radius? I was thinking of doing that but then backing the cross slide away to manage cutting depth and maybe setting up an indicator to come back to zero? Anyone thats used one of these please chime in.

P.S. ignore the bolt as the handle. Haven't had a chance to make one yet.

 

[markba633csi]

The answer is both- the ball turner sets the final diameter of the ball but you do use the cross slide a bit also since you
don't complete the ball in one pass usually

 

[RJSakowski]

I had made a ball turner where I could mount the tool on my com[ounfd to take advantage of the micrometer feed for adjustment of the radius but it didn't work too well. There wasn't enough travel on the compound to allow turning a larger ball and the device was too bulky and the chuck interfered with it which limited turning on the headstock side of the ball.

However, I had used the compound on my Atlas/Craftsman in the past to successfully cut concave surfaces which was very similar to what you are doing . to cut a true ball, it is important that the pivot point is directly below the spindle axis. To check that, I would make a preliminary cut and then rotate the cutter so it was at the rear of the center line. For a true spherical surface, the cutter will just touch the back side. If is is clear of the backside, the cross slide need to be backed out. If it is dragging, you need to advance the cross slide. Once this is done, you can zero the cross slide so you can return to that position for your final cuts.

If you are cutting only a half sphere, you can move the carriage to the right of your final position and advance it towards the left for eaxh successive cut. If you are cutting ore than a 50% sphere, you will want to lock the carriage and back the cross slide out from your previously zeroed position so you can make multiple passes.

To check my radius of cut, I would make an initial cut and measure the result with calipers or with a micrometer and adjust according. This can be done from the end if you have centered tha cross slide as described above.

 

[Jimsehr]

I have made many ball turners and I will tell you a good way to set radius size.
Turn a radius to make a ball. Looking at your tool try for a 2 inch ball.
Once you have a known size Say 2 inch ball or 1 inch radius. Take your turner to the mill and mill turner base and end of adjustable cutter holder flush.
Now you know when base and cutter are flush you have a 1 inch radius.
Now if you slide your cutter .100 to the center of axis you have .900 radius or
1.800 ball.
Now it is simple math to set radius of your choice.