View Full Version : zero or minimal runout - shaft part

05-12-2012, 10:58 PM

curious if anyone with more cutting / CNC knowledge can share some light on this. How hard would it be to get zero or minimal (below 0.05mm) runout on a part like this:


Material is stainless steel, the part will be supported in the highlighted sections, diameter is 20mm and 14mm on the bottom part.


Robin Hewitt
05-12-2012, 11:57 PM
Could the collar become a circlip?

06-12-2012, 10:25 AM
I'm afraid not as I need something to rest the bearing on.


Robin Hewitt
06-12-2012, 12:19 PM
Isn't that what circlips do best? Perhaps you are misunderstanding 'circlip' ?

The stainless will give out before the circlip does unless you are using some fancy grade.

Could you replace the end spigot with a circlip?

Do you really need stainless?

If you could use a 20mm linear rail with two circlip grooves cut in it... concentricity ceases to be a problem, the circlip grooves will not deform under load, you get a perfect fit in your bearings and the whole thing will be more rigid.

06-12-2012, 12:30 PM
Indeed Robin, confused circlip with a type of pin for whatever reason:)

Spigot stays, there's a part which mounts on the end.

Stainless isn't necessary, although it will work in a rather moist environment, so steel is out of the equation (can't use oil or anything like that to protect it from moisture either).


06-12-2012, 02:09 PM
Provided you use some metal that is stress reliefed, then 2thou run out is fairly easy.

I can't remember of the top of my head if the usual stainless bars (303, 304, 316) are stress reliefed or not. Non-stress reliefed can be used, however it may distort over time, or if subject to heat/cooling cycles.
You may want to change the design so there's a slight reduction in diameter between the bearing surfaces to make bearing installation easier.