In a message dated 9/22/2009 9:07:59 PM Central Daylight Time,
tr3driver@ca.rr.com writes:
> Acme threads are stronger than V-threads of the same pitch and major
> diameter, because less of the diameter is taken up by the thread (larger
> minor diameter). But the advantage mostly disappears when compared to
> V-threads of finer pitch; and oddly enough, standard V-threads are finer
> pitch than standard ACME threads.
>
> I thought about using ACME rod; but Home Depot doesn't carry it, and the
> 3/4" V-thread rod I used is such total overkill anyway (tensile strength
> around 20,000 pounds) that it just didn't matter. I guarantee it can pull
> your 3/8" ACME in half without even noticing the load (though I might need
> to get out the strong impact gun instead of the wimpy one).
>
Another advantage to Acme rods is that they will last longer. The threaded
rod at the hardware stores is all grade 2 and with the locking threads
(V-threads) they wear out. The one I used was good for about two spring
changeouts. The ACME version has done at least 6 and look good as new.
The coarser pitch of the ACME thread is an advantage when using a hand
wrench. If you are going to use an impact wrench (which, BTW is advised
against
by the makers of store bought compressors) you will need a REALLY DEEP
socket.
Maybe you can't buy ACME threaded rod off the shelf but McMaster-Carr will
gladly drop some off on your door step tomorrow.
One other thing, ACME thread being the way it is, you can't double nut the
top side and expect it to stay. So I drilled a hole and use a pin to lock
the top nut in place.
Dave
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