Survivalism & Self Sufficiency Topics > Do It Yourself - Projects, Ideas and How To

Beginners guide to nuts, bolts and threading

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ryerle23:
Great write-up, thank you for your hard work.

ncjeeper:
I would also add to use anti-seize in the freshly tapped hole just before you install a bolt for good. Otherwise it will rust together and it will be a bear to remove.

LvsChant:
+1 from me, too, Ohio Oz. Stop by the intro thread if you get a chance! Glad to have you here.

ohio oz:
Thanks for all the kind words guys, I'm glad you liked it.  It took much longer to do the writing and editing than to do the little project and photography!  I hope someone will read this and be inspired to repair that old "whatever" in the back of the garage, just like grampa used to do.

Is there interest in a similar article on metric hardware and/or pipe fittings?


--- Quote from: ncjeeper on June 13, 2010, 01:58:28 PM ---I would also add to use anti-seize in the freshly tapped hole just before you install a bolt for good. Otherwise it will rust together and it will be a bear to remove.

--- End quote ---

Good call!
Even if you don't use anti seize, it's important to use some kind of lubricant on threads, even a dip in engine oil or a squirt of WD-40 helps.  A bolted joint is used to compress two things together enough that they don't move in relation to one another.  In other words you are adding more force to assure the friction between the two parts is enough that the bolt(s) never try to bend or ideally don't even try to shear the bolt in two.  If you thread a bolt in a dry hole, most of the effort you put into torquing the bolt goes into overcoming the force of friction between the threads and under the head of the bolt.  It may seem nice and tight, but it may not apply enough force between the two parts to do it's job properly. 

That's why important assemblies specify one torque to be used with a specific lubricant, and another torque value with a different lubricant. A better lube allows the right force to be developed at a lower torque.

I work in an engine rebuilding shop, and just the other day we had a customer with a very expensive engine (a 540ci Merlin BBC for you gearheads, more $$$ than a few entire new cars!) with all the best in aftermarket parts.  A connecting rod bolt had broken, and after disassembling the engine it was clear that the original builder hadn't used any assembly lube on the bolt.  As the bolt was tightened, the force of friction caused the bolt's threads to constantly weld to and tear the base metal on a microscopic level.  All this welding and tearing takes a lot of force, so the builders torque wrench said everything was tight enough, though it wasn't compressing the parts like it needed to.  Less than 1300 miles later it's back in the shop being fixed...

Goatdog62:
Great, informative thread! Outstanding! +1

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