Re: [CAD_CAM_EDM_DRO] Ball/acme screw question

JJ,
You do not use the O.D. of the screw in the I.D. of the bearing. The
ends of the screw are machined or ground to the next standard size down, to
a snug fit in the bearing I.D.. My R & D in this kind of thing, is usually
done in the McMaster-Carr web site. www.mcmaster.com . They have bearings of
every size and shape available.

Marv Frankel
Los Angeles

----- Original Message -----
From: "JJ" <jj5412@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, October 29, 2002 4:23 PM
Subject: RE: [CAD_CAM_EDM_DRO] Ball/acme screw question


> Thanks for all the info everyone!
>
> One last (for now) question: Are acme screws their true diameter? Ie. If
> I buy a 1/2" screw, do I plan on using 1/2" ID bearings?
>
> Okay, one more: Does anyone make small mounting flanges for acme nuts? I
> just can't see a 2.600" flange for a 3/8" rod.
>
> Thanks again,
> JJ
>
> Be Kind, Be Careful, Be Yourself
>
>
>
> > -----Original Message-----
> > From: Marv Frankel [mailto:dcdziner@...]
> > Sent: Monday, October 28, 2002 11:11 PM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > 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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> > > http://groups.yahoo.com/group/jobshophomeshop I consider
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> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
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> 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........
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> 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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>