Piston Ring Locator

[Toolmaker51]

My first homemade tool post!

So I whipped up this little tool from a used piston to make it easier. The length between the top and bottom of the tool is within .003" all the way around, so much more accurate.
As I get in other engine types for rebuild, I will make the same tool for each.

Very good idea. I believe you could solve the .003 OOS issue easily.
The process of manufacturing washers [punching ID, stamping OD] does not insure flat parts. Next, surface of cast piston is likely not dead perpendicular to skirt, especially in 3 locations. Finally, small relative area of cap screw could 'dent' each washer into different cup shapes.

Use 3 smaller, narrower [there fore stiffer] contacts held the same way. 3/16" keystock, dowel pins, etc. 3 points of contact is always stable, yet no assurance each is on same plane.
Just like surveyor's tripod, adjustable legs AND leveling jackscrews.