Hard time w LCA's Today

[ShadowsPapa]

Also make sure you are torquing the nut, not the bolt.

That only matters if the surface area of the bolt touching the metal compared to the surface area of the nut touching varies or differs. If the contact areas are the same (hole on each side is the same size for example, and the nut surface and bolt head surface are the same) it won't matter.
In other words, if the bearing face is the same for both nut and bolt, it won't matter unless there are other factors.
If the bolt is an interference fit in the hole, torque the nut.

Basically, there is no simple answer to this as in some instances, it is perfectly acceptable to tighten the bolt head while holding the nut in place. In other situations, it’s fine to tighten the nut. It all depends on the application and the condition of the product or material being worked with. While in some situations you can apply torque to either bolt head or nut and enjoy a tight connection, there are circumstances where you should apply torque to one and not the other.

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[Pescatoral Pursuit]

That only matters if the surface area of the bolt touching the metal compared to the surface area of the nut touching varies or differs. If the contact areas are the same (hole on each side is the same size for example, and the nut surface and bolt head surface are the same) it won't matter.
In other words, if the bearing face is the same for both nut and bolt, it won't matter unless there are other factors.
If the bolt is an interference fit in the hole, torque the nut.

Basically, there is no simple answer to this as in some instances, it is perfectly acceptable to tighten the bolt head while holding the nut in place. In other situations, it’s fine to tighten the nut. It all depends on the application and the condition of the product or material being worked with. While in some situations you can apply torque to either bolt head or nut and enjoy a tight connection, there are circumstances where you should apply torque to one and not the other.

This appears to confirm:

https://www.boltscience.com/pages/nutorbolttightening.htm

It's a little more comprehensive than the old mechanic's class "draw the bolt to the nut" explanation.

 

[ShadowsPapa]

This appears to confirm:

https://www.boltscience.com/pages/nutorbolttightening.htm

It's a little more comprehensive than the old mechanic's class "draw the bolt to the nut" explanation.

Yeah, in a nutshell - it's logic. The idea is bolt stretch and 85-90% of the torque is the thread interference or drag.
So if something will cause the nut to drag more (like a flange nut for example) tighten the bolt. If the bolt head surface and nut surface are the same, then ask - is the bolt snug in the hole, etc.

That link is excellent - great pictures/diagrams and explanations.

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