Bolt Questions ???

[Sterff]

Is there a certain reason one would use a fine thread bolt over a nc bolt? I have always wondered why both are needed. Also what are common fine thread bolt sizes to stock up on? Thanks

 

[Travis E.]

I use coarse thread bolts in softer materials (plastic, aluminum, etc)and fine thread in hard materials (steel, stainless, etc...)depending on what I am building. What size fine thread bolts to stock depends alot on what you are doing. What do you regularly do that you might need fine thread?

 

[Sterff]

Right now I am using all nc bolts and use them from anything from equipment repairs to small mowers, etc.

 

[adam728]

Fine thread bolts are stronger because their minor diameter is larger.

If tapping holes, fine threads are easier in hard materials.

Course threads are better in softer materials, plastic, aluminum, etc.

Course threads assemble faster, and are more difficult to damage / cross-thread.

 

[Elroy]

Fine thread bolts are stronger because their minor diameter is larger.

If tapping holes, fine threads are easier in hard materials.

Course threads are better in softer materials, plastic, aluminum, etc.

Course threads assemble faster, and are more difficult to damage / cross-thread.

What he said

 

[Ign]

Also what are common fine thread bolt sizes to stock up on? Thanks

Yeah it really depends upon what you're doing. I'll often tap 1/8" plate for 1/4-28 and 1/4" plate for 1/2-20. I like to have some 3/8-24 on hand too. Not much scientific behind any of that, more like personal preference.

 

[yhprum]

Fine threads resist vibration induced loosening.

 

[Bigpigdave]

Fine threads resist vibration induced loosening.

Not necessarily true. Any fastener that is properly "stretched" will not loosen. Though, achieving proper "stretch" is often difficult.
Dave

 

[creativecars]

One reason to use fine thread fasteners is to have a need for more threads per inch. Especially when working with thin mterials. For example if you tap into a piece of plate that is 1/4" thick a 5/16 bolt with 18 tpi (UNC) it will have about 4 1/2 threads holding it in place, with 24 tpi (UNF)it will have 6 threads to hold with. UNF will also allow for a finer adjustment when using for holding presure or tension.

It is nice to keep some 1/4, 5/16, 3/8, and 1/2 around.

 

[Elroy]

Not necessarily true. Any fastener that is properly "stretched" will not loosen. Though, achieving proper "stretch" is often difficult.
Dave

Nice try but you're a little short on your facts

The clamping load from the fastener must exceed the load on the joint. If the the clamping loading is too small the fastener will fail.

Failure mode would be determined by the nature of the load and geometry of the joint.

http://www.boltscience.com/boltinginfo/pages/QuizExample.html

 

[srmofo]

Right now I am using all nc bolts and use them from anything from equipment repairs to small mowers, etc.

you probably wont find too many fine thread bolts in everyday equipment.

 

[t100]

may I recommend, there's a wonderful company called Air Craft Spruce, go to its website and order a Free catalog, here http://www.aircraftspruce.com/contactus.php

it won't cost you a dime, but, their catalog is literally a mechanic/engineer's reference book. you will find all the info you will ever need, not just fasteners, also on material and production method.

 

[Griff93]

Another reason for using fine thread pitch is the mechanical advantage when using as forcing screws for pullers and stuff.