Washer under a bolt head or not? What is your opinion?

[cuemaker]

I was gonna jump in and help Darryl with the science behind bolt torquing and how it works with yield and tensile strength. I reserve any thoughts on common hardware grade stuff, which is probably what your talking about.

I believe that most bolts and nuts that fall into an ASTM/ASME classification, have a washer face on them. F436 washers are only sometimes used. If conditions cause creep, belleville washers are super common.

[flylo]

Youse guys don't hold the head with a wrench and turn the nut?

That's what I do whenever possible. Nuts get turned, the bolt stays steady. Just seems better to me, always has. Besides, the nut usually has a washer under it................

Washer under the head if you need to make up distance with an AN fastener when the threads cannot be in the joint so you use an over-long bolt.

That's the way I do it too if possible but most people don't & screw up the finish.

[Glug]

An assortment of AN (aircraft) washers is invaluable. They're cheaper than hardware store junk washers, and the thickness is consistent. Aircraft Spruce is one supplier.

[elf]

Are you including machine screws in your bolt definition?