PDA

View Full Version : Ball turning tool



Gavin
03-30-2009, 12:16 AM
Stumbled across this idea for a ball turning device. The idea appealed to me as mounting in the toolpost means that I wouldn't have to remove the toolpost every time I needed to turn up a ball.

http://members.optusnet.com.au/moreshedstuff/Media/Projects/BallTurnP1220009.jpg

Whilst thinking about how to build it I had a thought that the reaction to the cutting forces would be back through the cross-slide leadscrew and nut because of the geometry of the tool rather than down through the ways as in a "conventional" cut.

Am I correct in that assumption and is this adverse for the lathe, would it place too much strain on the cross-slide screw & nut - or am I worrying over nothing?

I'm talking about running it on a chinese 12" x 24" lathe so it's not big heavy iron but it's not a mini-lathe either.

dp
03-30-2009, 12:46 AM
Worrying over nothing. The lathe can handle it. You can also use an off the shelf boring head such as this:

http://bbs.homeshopmachinist.net/showthread.php?t=33808

barts
03-30-2009, 12:47 AM
Stumbled across this idea for a ball turning device. The idea appealed to me as mounting in the toolpost means that I wouldn't have to remove the toolpost every time I needed to turn up a ball.

http://members.optusnet.com.au/moreshedstuff/Media/Projects/BallTurnP1220009.jpg

Whilst thinking about how to build it I had a thought that the reaction to the cutting forces would be back through the cross-slide leadscrew and nut because of the geometry of the tool rather than down through the ways as in a "conventional" cut.

Am I correct in that assumption and is this adverse for the lathe, would it place too much strain on the cross-slide screw & nut - or am I worrying over nothing?

I'm talking about running it on a chinese 12" x 24" lathe so it's not big heavy iron but it's not a mini-lathe either.

This is a pretty common design. Most ball turning is pretty light duty stuff, and you're not moving the lead screw when the load is applied, so that wear is avoided. If you're going to hog out 2 5/16" trailer balls, maybe a different design is called for, but not for a few ball handles...

There are some nice examples of these built to slide right onto a Aloris style tool post kicking around on the net..

http://www.haythornthwaite.com/Ball%20Turning.htm

He uses a boring head - pretty simple and very easily adjusted.

- Bart

Gavin
03-30-2009, 01:07 AM
Thanks for the reassurance - I'll start building it tonight....the other beauty about this design is that the block that fits in the toolpost is drilled and reamed using a drill chuck held in the lathe chuck, therefore the bore is exactly on the lathe centreline, and lends itself to being used as a boring bar holder when not in use for ball turning.