How would YOU go about this job.

[Suzuki4evr]

Hi all.

I know how I will do this job,but other input is always welcome. The pics below are of a windmill rotation mechanism and the client wants me to open up the groove for the balls from 10mm to 12mm balls. There will be space for about a 1/4 ball less but that leaves space for more grease right.

What I will do is use a 12mm ballnose endmill and use the rotary table on the mill. The other option is the lathe and form tool used in a trepanning way,but I am not fond of trepanning.

Your thoughts???

The bottom half.

The top half.

I just added some balls for perspective.



Thanks for viewing.
Michael.

 

[wayback machine]

I think I would do it in a lathe, with a specially ground form tool - But as always, YMMV

 

[mmcmdl]

Mike , I would go with the ball mill in a RT . Trepanning that radius will chatter quite a bit , specially in a smallish lathe .

 

[extropic]

Your approach sounds reasonable to me and it should be easy to maintain the same diameter race on both halves.

It would be a good idea to install a short length (2mm?) of Teflon tube between each of the new balls, as separators, so the balls don't rub on each other.

 

[Parlo]

The tracks could be a truncated vee, giving a 4 point contact on each ball. Should be simple enough on the lathe with standard tools and the compound slide. Just note the settings for the first one and repeat on the other. It will leave room for grease too.
Edit: spacers betwen the balls will make a big difference, the adjacent ball perimeters are moving in opposite directions.

 

[benmychree]

I would do it in the lathe with a form tool, but then, I have a heavy lathe ---

 

[Cadillac STS]

Me, I would not work the metal but get a ready made thin thrust bearing where the balls go. In a lathe maybe face off flat to make room if needed.

Washer-bearing-washer. That type.

Thrust bearing is made for that and will take a heavy load.

 

[fixit]

Me, I would not work the metal but get a ready made thin thrust bearing where the balls go. In a lathe maybe face off flat to make room if needed.

Washer-bearing-washer. That type.

Thrust bearing is made for that and will take a heavy load.

I agree, this would be the best way to solve the problem.

 

[OTmachine]

The spacers are a good idea, but I don’t think it is required. Bicycle frame head tubes, crane house pivots and such do not use them. Where the rotary motion is minimal in any direction, the balls do not have much chance of racking up to act like a sprague clutch.

 

[Suzuki4evr]

Mike , I would go with the ball mill in a RT . Trepanning that radius will chatter quite a bit , specially in a smallish lathe .

I do have a big lathe and small one,but still like the mill method more.