Radius turning fixture?

[Net30]

My lathe has a single 3/4-10 bolt that runs from the compound T-nut through the tool post. I wanted to make a radius picture that can go on using the same T nut and this is what I came up with. Probably won't be able to finish it for a while but I think it looks cooler than most of the ones I've seen so far. I'm just not sure if I'll be able to secure it to the T nut and if so, how secure the dovetail will be. Anyone do anything similar?

 

[Janderso]

My lathe has a single 3/4-10 bolt that runs from the compound T-nut through the tool post. I wanted to make a radius picture that can go on using the same T nut and this is what I came up with. Probably won't be able to finish it for a while but I think it looks cooler than most of the ones I've seen so far. I'm just not sure if I'll be able to secure it to the T nut and if so, how secure the dovetail will be. Anyone do anything similar?View attachment 500126View attachment 500127View attachment 500130

I like the tapered bearing. Nice job.
I made a simple radius turner a while back. I believe this came up in the forum about a year ago.
Very useful tool.
Keep us posted.

 

[Net30]

Now I need to be able to freely rotate the top without unscrewing one end. I thinj i need a set screw to capture the pin. Easiest way would be on a new t nut but then I think I'd make the taper bearing useless. Any suggestions? I'm all ears.

 

[GeneT45]

That looks a lot like the "Holescreek" ball turner. You might search for those drawings to see if they have any ideas for you.

GsT

 

[rwm]

At least on my machine, the compound top surface would be much too tall for such a tool. What is the distance you will have from the top of the rotating tool holder to the spindle centerline?

 

[talvare]

That looks a lot like the one I made about 10 years ago. I don't use it a lot, but it has come in handy several times. With the one I made, I remove the compound slide and replace it with the radius tool. Couple of photos of mine attached.
Ted

 

[rwm]

I love the scale you put on that!

 

[Rex Walters]

Ball turners are fun and surprisingly satisfying to use. They really dress up a lever arm (tapered or straight shaft).

At least on my machine, the compound top surface would be much too tall for such a tool.

I'm limited to 1" diameter balls with Jim Sehr's simple ball turner design. It mounts on the compound of my 10" lathe. It's perfect for ball-handled levers. I used it just the other day to make this ball handle on a surface grinder I'm restoring:

@Net30's design is adjustable and can face the end of the stock, unlike Jim's design. Jim just uses a flat topped piece of HSS or carbide as the cutter. I don't find either to be a real limitation in practice, and I've not yet needed to turn a ball larger than 1" diameter. It wouldn't be hard to modify the design to add some relief to the cutter to allow facing, or a step in the base to turn larger diameters if I had a need.

EDIT: I forgot that I wrote an entire thread and a blog post about the design!

 

[rwm]

On my 10" the distance from the compound is about .900. But then you have to subtract the thickness of the rotating platform for the tool. I guess as long as you have .500 left you could turn 1" spheres no problem. I love the tapered bearing idea! I was just wondering, why not mount it on the cross slide?

 

[Rex Walters]

why not mount it on the cross slide?

The compound is a real PITA to remove and reattach on my lathe, and some hobbyist lathes don't make it easy to mount anything to the rear of the cross slide. I actually built an entirely new cross-slide for my lathe expressly to be able to mount stuff on the rear. Sane people probably wouldn't go that far.