Russian machinists.

[Bented]

What effect does ball size have on finish? I have some down hole check valves that are 1.25 and 1.50:diameter, with a mirror finish.! They are harder than the hubs of hell, as they were used in an oilwell pump 6000 feet down.

They have been finish machined already.
Ballizing is a Finishing Process, you do not want to resize a bore this way. If you press a a 1.5005" carbide ball through a stable 1.499" bore you end up with a 1.500 bore with a burnished finish.

[Corbettprime]

What effect does ball size have on finish? I have some down hole check valves that are 1.25 and 1.50:diameter, with a mirror finish.! They are harder than the hubs of hell, as they were used in an oilwell pump 6000 feet down.

[plunger]

Ive seen this before using a simple bearing used for lining things in a 3 jaw .This is a heavy duty one but how do you know how much it can roll to get consistent results.

[Bented]

Roller burnishing has been used in manufacturing for 60 years in the US, Ballizing is a related process where a very precise diameter ball is pressed through a bore bringing it to size with an excellent surface finish.

I have always been surprised that more home shop machinists do not use this method as it delivers most everything that a hobbyist desires, close diameters and superb finishes. I can only assume that cost deters most from doing it.

[Tom S]

I have that same micrometer

[MattiJ]

Tool was able to shrink surprisingly thick walled workpiece by a large amount and with what looked like only moderate feed force!

edit: I think it was mostly visual trick with oil running on the workpiece. Can someone tell what he is saying at around 4:25 about size reduction?

BTW this might be a perfect use for those scrap-auto sourced tungsten carbide balls. Some CV joints have tungsten carbide balls rolling against sort of rough-finished races.

[MattiJ]

I have seen some of his videos but this was new to me. Interesting tool, newer seen one like that.

[danlb]

I've learned that Russian machinists is usually a bad idea, just like rushing your proctologist is a bad idea. After all, when they're Finnish, they're Finnish.

[plunger]

Some interesting stuff comes out of Russia.
https://www.youtube.com/watch?v=GZkpvM4kGvs