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Old 02-11-2019, 06:03 AM
Freemasm Freemasm is offline
 
Join Date: Nov 2017
Location: Orlando
Posts: 135
Default Basic torque rule of thumb

From my Space Shuttle Engineering days (I learned those old North American Aviation/Rockwell International/NASA specs before I learned any FAA related specs): There's a reason there's a range for torque values. I'm sticking to shear applications only.

- You torque to the mid value above the running torque (self locking nut) when you torque from the nut side. (preferred method)

- You torque to the high side when you have to torque from the bolt side as friction in the stack will add to the perceived (not actual/applied) torque

- You torque to the minimum value when utilizing a castellated nut then align the next hole (only for a non-specifically engineered application).

There is a lot margin in the fastener as the values for tension are typically ~ 90% higher. Don't forget about "Lite" washers when they make sense.

For the Aircraft Structural Engineers that may read this; yes, I simplified this and there are exceptions. I won't get into any back and forth. Remember the audience and application. I'm talking good shop practice here.
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