A NEW IDEA FOR AN OLD TOOL!

[Philip Davies]

I like this a lot! But I doubt I shall need to make one! I expect I shall find something like that soon, if it’s not in a box of odds!

[rgsparber]

Rick, thanks for the interest again! Yes, any vise with uneven jaws in height (or with longitudinal clearances) can cause this and other position errors. As this device works with tangency points, it would be interesting to at least ensure that these points are reliable (or work with some type of templet as I have shown). Manufacturing tolerances must also be observed, in this and other cases.

Attachment 38319

A simple question, just out of curiosity: how did you check the accuracy of your center finder?

https://rick.sparber.org/acf.pdf

That tool has evolved into https://rick.sparber.org/UniversalCenteringTool.pdf

To test, I would drill a holed in bar stock. Put a pin in the hole, and measure the altitude of the pin on a surface plate. Flip the bar the over and measure again.

Rick