Engineering principle behind this type connection

[jwmelvin]

Yes try what rabler suggests. The rotating piece should not rock. A cone spring (Belleville washer) will help, as would a plastic washer between that and the rotating piece. It may be an easy way to what you really care about. Some friction may be good for these, to dump vibrational energy.

What materials are you rotating piece and the stationary mating piece?

 

[Maplehead]

Yes try what rabler suggests. The rotating piece should not rock. A cone spring (Belleville washer) will help, as would a plastic washer between that and the rotating piece. It may be an easy way to what you really care about. Some friction may be good for these, to dump vibrational energy.

What materials are you rotating piece and the stationary mating piece?

Mild steel

 

[aliva]

Where is the placement of the bearing?
Do I bore out a space for it at the bottom of the cavity where the ball turner's rotary "disk" sits?

Yes. Bore between the top and bottom disk and plate

 

[Jimsehr]

I like simple. I don’t think you need a bearing to make the tool better. I think I could make the tool so it could have a longer life if I wanted . I made it thinking I would only make about 100 balls in a home shop. So I was not planing on production runs. Maplehead I think you saw a video of one of my radius cutters or ball turners working. I don’t remember if it was vid of cutting a ball or vid of cutting a radius into the od of a bar. I have made radius cutting tools where swing axis of the cutter was soft leaded material and the mating base was also plain steel plate. No heat treating at all. I just used a little oil and it worked.

If you want my advice email me and I will try to help. Jimatcf@hotmail.com

 

[Jimsehr]

Maplehead
If I was making the balls I would use easy to cut leadloy material. I think I have ball turner that will cut 3/4 ball so maybe I will cut a few just for fun. Leadloy will give a good finish and cost is probably same as mild steel. Also it might be easier to form a 3/8 radius.

 

[Jimsehr]

I hand ground and formed all these balls in my avatar.

 

[Maplehead]

I like simple. I don’t think you need a bearing to make the tool better. I think I could make the tool so it could have a longer life if I wanted . I made it thinking I would only make about 100 balls in a home shop. So I was not planing on production runs. Maplehead I think you saw a video of one of my radius cutters or ball turners working. I don’t remember if it was vid of cutting a ball or vid of cutting a radius into the od of a bar. I have made radius cutting tools where swing axis of the cutter was soft leaded material and the mating base was also plain steel plate. No heat treating at all. I just used a little oil and it worked.

If you want my advice email me and I will try to help. Jimatcf@hotmail.com

Hi Jim
I took the advice of others here and used what I had on hand to update the existing turner. I didn't use any bearings as I don't have any but I did make a brass bushing and fit that in. I also drilled out most of the "hockey puck" from the middle so that the lat 1/4" of the diameter is what contacts the base. All seems to make it better but I still have one issue. I cannot keep it tight. I don't have belleville washers so I used a concave washer. The washer is on a bolt that faces up and screws into the puck. No nut involved. Maybe I need to redesign that to include a nut?
If I can just set the jig to a certain tightness, while still having smooth rotary movement, then I know it will work well now.

 

[Jimsehr]

Hi Jim
I took the advice of others here and used what I had on hand to update the existing turner. I didn't use any bearings as I don't have any but I did make a brass bushing and fit that in. I also drilled out most of the "hockey puck" from the middle so that the lat 1/4" of the diameter is what contacts the base. All seems to make it better but I still have one issue. I cannot keep it tight. I don't have belleville washers so I used a concave washer. The washer is on a bolt that faces up and screws into the puck. No nut involved. Maybe I need to redesign that to include a nut?
If I can just set the jig to a certain tightness, while still having smooth rotary movement, then I know it will work well now.

I am going to go out to my shop this morning and see about making a guick and dirty 3/8 ball turner. Maybe even a form tool to see if that works better.

 

[jwmelvin]

I cannot keep it tight. I don't have belleville washers so I used a concave washer. The washer is on a bolt that faces up and screws into the puck.

Do you mean if you tighten it, the motion locks (too much friction) or the screw works itself loose?

If the former, a compliance like the Belleville washer or a plastic washer may help. But your concave washer should do the same thing, right? If you mean the bolt loosens, what about some threadlocker?

Sounds like you got the mechanism fitted better, so that’s good.

 

[Maplehead]

Do you mean if you tighten it, the motion locks (too much friction) or the screw works itself loose?

If the former, a compliance like the Belleville washer or a plastic washer may help. But your concave washer should do the same thing, right? If you mean the bolt loosens, what about some threadlocker?

Sounds like you got the mechanism fitted better, so that’s good.

I can only tight the screw to a certain point before adds too much friction to the rotary motion. However, when I start to add a load to the jig, meaning I start cutting, I notice the rotary motion is looser which allows for a slight wobble. I want zero wobble.