Northern Hardness Tester how to calibrate

[ruralearl]

Please tell me how to calibrate a Northern Hardness Tester circa 50's-60's so that the tester reading indicates test block specification. Thank you

 

[eKretz]

It says how to do this in your 4th photo. Assuming you have a known test block, you put it in the tester and load it, then there's an adjustment on the bottom so that you can set the dial to agree with your known test block.

 

[ruralearl]

I saw that, but misunderstood it. Thanks for the response, Earl