Re: [CAD_CAM_EDM_DRO] Ball/acme screw question

In a message dated 10/28/2002 3:55:00 PM Central Standard Time,
jj5412@... writes:

> Why would you choose a multistart screw over a single start screw?
>
> Are acme thread screws more efficient that generic threaded rod?
>

JJ:

I am NOT a "trained" machinist; I am just one of those hobbiests who THINKS
he "can DO that!". So, lemme try to answer your questions: First, a two-
to four-start screw causes MORE linear move (of the "nut") per turn. A
"four-start, 1/8"-pitch screw" causes a full 1/2" per turn move! I have used
some "four start" from BSA on a couple of plotters I have built, and the
"speed" of movement of the pen is significantly greater than you might have,
say, on a little mill or X-Y Table, etc., with only single-start!

Second question: Certainly! That is why the stuff exists! a "V-thread"
"jambs up" somewhat, when "tight", and you do NOT want this in any kind of
"CNC machine", etc! Even the BETTER ordinary vices have ACME thread!

Besides, "gerneric" threaded rod---you mean the rolled, zinc-plated stuff
from Home Despot? UGH! That is for FASTENING, not
MACINE-lead-screws!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

HTH! Jan Rowland, old ugly troll


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