Ball turning on my Rivett watchmaker's lathe

cazclocker

Purveyor of cheese.
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I just got done trying out a tool that is (sadly) NOT mine, and I have to return it to its builder/owner tomorrow! It's a radius-turning tool that mounts into the quill of the lathe. He's a friend and a fellow Rivett nut, so he loaned it to me and I'm posting my first try at using it. Tom (the builder) says it's an "up-and-over" design based on an article from Model Engineer magazine.
I'm never sure what order the pictures are going to upload. But basically I'm attaching pictures of the tool laying on my bench unmounted, then closeups of the cutting head, then mounted in my lathe's quill, then of the final product.
The tool has a round cutter bit, ground at a slight (10-degree?) angle. I found that the round profile of the bit was WAY too easy to bite into the end of the work behind the ball, when approaching the end of the ball where it joins the handle. Also, the round profile cuts a tiny radius at the handle/ball junction, instead of the sharply-defined corner I would have preferred. I suspect a square graver bit would solve both of those issues.
Anyway, it was simple to operate, very well engineered (almost OVER-engineered), and did a fine job. I ended up with a couple of boo-boos from the cutter bit hitting the handle behind the ball, but I got most of them out (and sharpened the handle/ball junction) with a small india stone.
Fun stuff! I wish this tool was mine!

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Here's a link to a video I took for part of the ball turning operation. You'll notice I put a piece of masking tape over the tapered part of the handle, right up to the ball. That was because twice I accidentally scored the handle next to the ball with the round cutter bit. The tape helped a little bit but I still had to watch the cut carefully to make sure I didn't go too far.

CLICK HERE
 
Very cool tool. You watch maker guys always amaze me. I like how the cutter works on this.

Jeff
 
Lovely little tool. It looks like one of the boring head based turners I have seen. If you decide to build your own, that may be a place to start.
 
Thanks guys for comments. It does seem to resemble a boring head, doesn't it? I have to say though that it seems over-engineered, given the intended function which is just ball turning. I can't help but feel that somehow there must be a simpler way. Maybe in a year or so I'll have designed and built a simpler ball turning tool. In the meantime, I have been privileged to have a friend who would loan me such a gorgeous bit of his own work just so I could have a bit of fun playing with it. That makes me a lucky boy!
...Doug
 
It's over engineered if you just want to make decorative objects, but if you want accurately sized spheres, then this is just the ticket. Because you have graduations on the dial, you can adjust things very accurately. Also, sometimes the joy in making a tool that nice is in having done it ;)
 
It's over engineered if you just want to make decorative objects, but if you want accurately sized spheres, then this is just the ticket. Because you have graduations on the dial, you can adjust things very accurately. Also, sometimes the joy in making a tool that nice is in having done it ;)

Yes, I suppose you're right - it was the dial's graduations that made the tools so brilliantly simple to use! I probably shouldn't have made that remark because in truth, as soon as I unwrapped it from the package (when it was sent to me), I spent quite a few minutes just examining it, and admiring the work that went into it! I took a LOT more pictures of it than I included into my original post.

My friend Tom, who loaned the tool to me, is a machinist, woodworker, model engineer, and former university physics professor! So the tool is right up there with the kind of thing he likes to create. I wish I had his talent and experience!
 
Thanks for the post. I think I have all the parts to make one ,so its on the list of things to do.
Brian
 
A special thanks from me as I've never seen anyone turn a ball or sphere on a lathe! It's given me some things to think about!

Your equipment is gorgeous too!! :man:
 
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