Ball Turner Experience

Jimsehr said:
search this ball turner by Jimsehr. Jan 21 2022
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That turned out to be harder than you'd think, but I finally found the posts you meant.

For the record:
Here's a better thread with a link to a (slightly) higher resolution photo of that last bit:

www.hobby-machinist.com

Hemispherical radius cutter I made

Home made tool for cutting radius. https://photos.app.goo.gl/AtZUvTlcEwBGx8Y33
www.hobby-machinist.com www.hobby-machinist.com

Note that I misunderstood Jim. He didn't split or turn back the puck, he just used a puck diameter smaller than the radius in the end of the part. The puck rides on a base that doesn't stick out as far, and the puck goes into the cavity of the bowl on the end. The maximum depth you can cut is the distance from the tip of the cutter to the left edge of the base (once it contacts the edge of the bowl, you're done). The radius of the arc is the distance from the tip of the cutter to the center of the puck.
 
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If you don’t have any 1/4 round blanks for cutters I looked on ebay and found some For cheap. And if you buy a few they will last for years. Warning if you want to shorten them you can score them and hold in a vice and with a guick blow of a hammer they break at score line. But for safety cover with a rag before hitting as sometime chips will fly in your face.

Jimsehr
 

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Jimsehr said:
you can score them and hold in a vice and with a guick blow of a hammer they break at score line.
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You want to score all the way around, or you risk having a chip break off the side. Ask me how I know.

A cut-off tool in a Dremel or angle grinder works better for me than the corner of a bench grinder wheel.

Just finished an updated 3D model with drawings. This slight modification allows up to 1" diameter balls on my lathe:

Screenshot 2023-07-27 at 5.58.19 PM.png

As promised, I created a new thread here: https://www.hobby-machinist.com/threads/jims-truly-simple-ball-turning-tool.107341/

I'll now stop spamming this one!
 
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Jimsehr said:
Rex
When I made my ball turner I thought how often does a hobby guy need to make a ball?
Do I need a bearing for an axis just to make a few balls? NO. Does it need to be hardened and ground? NO. What size would most home shops want. How many hobby guys would ever make a 6 inch ball? Very few. So I went with my motto( Make It Simple ) First I made a ball turner that I could adjust the ball dia and it worked great. But you still have to fiddle around to get it to size. Also I had never seen the end of a round cutter used as a cutting tool. So I tried it. It worked and takes no skill to grind. It can turn the ball or an od but it can not face. I can make a radius on a hss tool within a thousand of being true. With out all the hassle of heat treating. If I want I can make a radius .265 .When I made my Jimsehr ball turner I also made a few extra blank blanks so if I wanted to make some thing like a metric radius I was ready.
First pic is hand made radius tool second is blanks to make different size radius cutters. And to me it is faster than adjusting an adjustable cutter.
lf I needed a thousand balls I would make them on a CNC.
jimsehr
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Jim,
After watching your video I began planning the build in my mind. My first thought was to add a thrust bearing top and bottom.
You say it’s not required. I’m having a hard time visualizing the simple design working smoothly without chatter or too much movement, yet, I just saw it used with my own eyes.
I need to make one!
 
Janderso said:
thrust bearing
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Yup. I was also worried about friction, especially if puck and base were dissimilar metals. Thought I’d want at least a nylon washer as a thrust bearing.

Turns out it’s not a concern at all, at least up to 1 5/8” dia pucks. They turn smooth as anything as long they are truly flat, have a reasonable surface finish, and have a pivot hole that is pretty tight but still a slip fit.

Just stone a wide nose radius on your facing tool.
 
Janderso said:
Jim,
After watching your video I began planning the build in my mind. My first thought was to add a thrust bearing top and bottom.
You say it’s not required. I’m having a hard time visualizing the simple design working smoothly without chatter or too much movement, yet, I just saw it used with my own eyes.
I need to make one!
Click to expand...
I work hard at making a tool as simple as I can and that can be harder than making a more complex tool. As Rex knows my goal is
MAKE IT SiMPLE. Seems like many people try to improve on my tools without trying them as I made them. For example everyone said a round tool straight up would not work. As seen in video round tool cuts just fine. And needs no skill to grind. After machining for 70 years I still have a few tricks up my sleeve.
 
As many of my ideas come when I can not sleep at night I think I dreamed up a new version that is even a little more simple than the one I have been using for years. I will have to make new version and try it out before posting a video.
jimsehr
 
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