Cylindrical square from a lathe tailstock.

[tonyfoale]

-Wow! Thanks, Tony for yet another inspiring and educational video!
For years I've been on the lookout for a 1-ish ft long, 2-3" dia hydraulic piston at scrap yards for precisely this purpose.

An hydraulic piston shaft should be good, but are they usually hardened or chrome plated? I have never tried lapping chrome.

Q: I wonder about your sequence of lapping and the grits chosen - any info to share on that, please?

I do not know the grit size. I have some 1200 grit diamond but that was a bit fine for removing much metal, great for a mirror finish but my concern in this case was not a shiny finish. I had several lots of valve grinding paste and one tube emphasised that the grit was all one size (it did not say what that was), so I used that one. Not a scientific choice but a practical one.[/QUOTE]

All the best for the coming new year!

Cheers
Johan

Thanks, and the same to all inmates of this forum.