fine/coarse threads question

Sep 09, 2005 2 Replies

When do you use a fine thread? Why?



Afaict there is no real strength or accurate placement difference as long as more than a few threads are mating.



Okay it's going to be a lot easier to tap a 22x1.5 mm hole in 3/4" stainless than a 22x2.5 mm hole (I tried the latter earlier, I am still sweating and there is now a spanner apparently welded at right angles to the tap), but are there any other advantages/disadvantages?



Thanks



Coarse threads are used in low-strength materials as they are less likely to pull out, and also less likely to jam when inserting, and quicker to manufacture.

Many engine makers used coarse threads on one end of a stud to go into alloy and fine for the steel holding down nuts.

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

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