Re: Lead Screws...where do you get them???

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<davemucha@j...> wrote:

> One thing we don't often mention, or don't mention enough is that
> leadscrews are precison shafts with threads. ACME screws are

similar to all-thread (threaded rod) but with a different screw
pattern..............

If a person plans to use Acme screws, there are a few things to look
for in order to get the best results on your machine. Some Acme
stock has cut threads and some has rolled threads. Avoid the cut
thread material, because it's surface finish doesn't compare to
rolled threads, and will begin to wear the mating thread
immediately. Rolled threads offer a superior surface finish and
much smoother movement. Rolled thread stock is available in 1018
and 4140 alloys. Go with the 4140 due to it's higher surface
hardness (Rc 24-32), as this will also increase the wear life. The
final variable is lead accuracy, or in other words, a measure of how
accurately the screw will place the table where you think it did
based on your motor input. 2C class Acme stock is readily available
with lead accuracies of .009"/ft, and .003"/ft. The .003 stock
costs roughly twice the .009, but really gets you into the range for
close work. Nook Industries makes a range of leadscrew quality Acme
stock and nuts, and MSC is a ready source http://www.mscdirect.com
A 3 ft. length of 3/4-5 4140 .003 lead accuracy stock and a bronze
nut will cost about $50. For comparative accuracy, the lead error
of standard precision (not ground) ball screws is .004"/ft.

Cliff