Re: [CAD_CAM_EDM_DRO] Ball/acme screw question

Yep, I'll take a 101 from anybody. some think of a nut by its length i
consider a nut by the amount of thread engaged. If i used a 4 lead screw and
put the same amount of thread engagement on one of 4 threads then the nut is
long but stronger..cul brian f.

----- Original Message -----
From: "Marv Frankel" <dcdziner@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, October 28, 2002 11:11 PM
Subject: Re: [CAD_CAM_EDM_DRO] Ball/acme screw question


> Brian,
> Actually, I'm somewhat of an expert, and the reason for a
multi-lead
> screw is this. You want a nut that will advance 1" in 4 revolutions, but
if
> the shaft is fairly small in diameter, the depth of the thread, if you cut
> it for a normal 4 threads/inch, would weaken the shaft considerably.
> Instead, you cut it 4 threads/inch, but at the depth used for 8
> threads/inch. You then have spaces between the threads in which to cut an
> additional lead at the 8 threads/inch depth. You then end up with a screw
> that appears to have 8 threads/inch, but the nut will advance 1" for 4
> revolutions. The whole thing has to be done on a lathe, and sounds
> complicated, but it really isn't. In the past, I've generated screws with
as
> many as 4 leads. They looked like the threads were very fine, but the nut
> would fairly fly down the screw.
> You just had a lesson in "Screwing 101".
>
> Marv Frankel
> Los Angeles
>
> ----- Original Message -----
> From: "Brian" <ka1bbg@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Monday, October 28, 2002 2:41 PM
> Subject: Re: [CAD_CAM_EDM_DRO] Ball/acme screw question
>
>
> > Hi, I am no expert but a few things to think about. Multiple lead acme
> > screws means you have several threads instead of one so they tend to
last
> > longer and are stronger. Rolled acme thread has been going on for a long
> > time and the acme rods i bought the other day are nicely finnished and a
> > quick check says their ok on the length. a "v" thread begins to wear
> quickly
> > and once it gets sloppy it weakens as it wears out. an acme thread stays
> > rugged even as its wearing to a point. As for efficient i cant answer
but
> > there are ground threads of all kinds out there some last for many years
> > even if they are "v" or acme or even buttress thread. Each has a best
use.
> > Take a look at the size you want and then look at the different grades
> > available. 1/2-10 acme b2 is the cheapest because of so much use, if you
> > order a 15/16-16 thread custom made to your spec's then expect to pay
> > premium big bucks. Sometimes the nut and the retaining method(back to
back
> > bearings or nuts) is the most important part. cul brian f.
> > ----- Original Message -----
> > From: "JJ" <jj5412@...>
> > To: <cad_cam_edm_dro@yahoogroups.com>
> > Sent: Monday, October 28, 2002 4:53 PM
> > Subject: [CAD_CAM_EDM_DRO] Ball/acme screw question
> >
> >
> > > (Hoping this is on topic)
> > >
> > > In my quest for constant upgrades to my CNC mill/router/pcb thing, I
> > > have a couple of questions:
> > >
> > > Why would you choose a multistart screw over a single start screw?
> > >
> > > Are acme thread screws more efficient that generic threaded rod?
> > >
> > > ADVthanksANCE,
> > > JJ
> > >
> > > Be Kind, Be Careful, Be Yourself
> > >
> > >
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if
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> > http://www.metalworking.com/news_servers.html
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> > http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
> sister site to the CCED group, as many of the same members are there, for
OT
> subjects, that are not allowed on the CCED list.
> >
> > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
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>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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>