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Calibrating the Harbor Freight torque wrench.

An engineer at Caterpillar posted on practical machinist gunsmithing how to calculate max torque on a screw. He explained the whole wax, oil, and dry derating and 1.5 times the root [minor diameter] of engagement before the male screw breaks and the female thread stops stripping.

To drill and tap 10-32 holes the thin [that means the female is going to strip first, if you have not been paying attention] Mosin Nagant receiver and cantilever a scope base...
I bought an inch pounds torque wrench at Harbor Freight for $20.
I milled some mild steel to .1" thick.
I drilled and tapped 4 holes with #21 drill.
I expect that I should be ok with 52% of the usual high ratings
...a) waxed 52% of 34 in lb = 17.8 in lb, but measured a 15 and a 16 yield
...b) lubed with oil or grease 52% of 51 in lb = 26.5 in lb, but measured yield at 28 in lb
...c) dry 52% of 68 in lb = 34.7 in lb, but measured yield at 34 in lb

I put on loctite and torqued the scope base to 20 inch pounds.









Yes, I thought metric torque in my mouth was so funny, I got my dentist to pose.
I used to negotiate dental prices with his father.

Dental implant insertion torque
Minimum of 32 Ncm insertion torque was necessary for implants to achieve osseointegration. The minimum torque that can be employed to attain primary stability is undefined.

The cadaver bone stripped out. I had to go home and heal.

The next implant was cow bone, and it prospered in my jaw bone, and took the 32Ncm of torque the first time.