Proofing a square

[Maryak]

what about a rigid square to a thou or less?

We used to give them a judicious tap with a copper hammer or a piece of hardwood. :

Best Regards
Bob

 

[gilessim]

Here's my granddad's square, sorry for the bad pic, the good camera took a drop down the stairs but it does say 1911 on it !, he also told me about the down and dirty "judicious tap", laid as in the pic, on an anvil ,hitting on the corner inside or outside, depending which way it's out

Giles