Re: [CAD_CAM_EDM_DRO] Ball screw cost and sources

----- Original Message -----
From: <JanRwl@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, May 25, 2003 1:21 PM
Subject: Re: [CAD_CAM_EDM_DRO] Ball screw cost and sources


> In a message dated 5/25/2003 10:42:52 AM Central Standard Time,
> acortez@... writes:
>
> > Just wondering about the approximate costs of the precision rolled
> > ballscrews and preloaded nuts that would be involved and the names of
some good
> > suppliers. I'll probably only need about 20" for the X axis and about
12" for the
> > Y axis.
>
> Cortez: I have bought precision-rolled ballscrews and ACME screws from
BSA
> in San Jose, CA (www.bsa.com??? Not sure!). They offer ready-to-use
"screw
> kits" ONLY for Bridgeport machines and knock-offs. For the little ENCO
you
> mention, you would need smaller-diameter screws and end-machining. You
CAN buy
> "cut to raw-length" screws with nuts (never forget! PRELOADED
double-ball-nuts!)
> and then do the end-machining yourself, IF you are enough of a machinist
to
> do that turning. It IS a task!
>
> I do not know what the approx. cost for what YOU need would be, if
> end-machining were available, but I would GUESS several hundred dollars.
Just for the
> raw-cut screws with preloaded ball-nuts, for YOU to do the ends, perhaps
around
> $200? I just don't know!
>
> There are a couple other firms that supply ball-screws with nuts, the only
> one that comes to mind right now is Thomson, the same firm that made
itself
> famous with the linear ball-bearings and hardened shaft-ways. I do NOT
have a
> clue what their pricing is like for sizes. Probably "up there", as I am
guessing
> the only screws THEY offer would be very precision, perhaps ONLY "ground
> after rolling"?
>
> IGUS? THK? No clue! Sorry! I have built several smallish machines
with
> ACME preloaded Turcite nuts, but setting the preload so there is no
> appreciable backlash on those will result in a considerable "drag" on the
screw,
> meaning the steppers or servos you use will have to be able to overcome
this drag,
> PLUS the forces required to move the cutter into the work. But if that is
not
> a factor for you, the use of ACME screws with those preloaded Turcite nuts
can
> work fine, and save you Gigabuck$. ONE problem with those
> fiberglass-filled Turcite ACME nuts: The abrasion of the
microscopically-fine glass-fibers in
> it has TWO bad effects: It causes fine "screw-dust" to build up inside
the
> nut-threads, and the slow removal of material from the screw-steel begins
to
> become quite noticeable (screws get FINE polish on them where the nut
hangs
> around!), so the EASE of turning the screw can vary CONSIDERABLY between
the
> region where the nuts most-often reside, and the "far ends" of the screws!
All
> this kinda thing is rarely discussed to sufficient degree in the catalogs
and
> "white papers" that might come with the hardware, so that's why we OLD MEN
> sometimes shyly mention EXPERIENCE! There just isn't ANY substitute for
that!
>
> Which brings me to a closing OT trivia: Back when I was in my thirties, I
> was visiting a 30-something machinist who had perhaps 5-7 years experience
IN a
> machine-shop. We were talking nuts-and-bolts, as I was dreaming up my
first
> CNC lathe, controlled by an ancient PET. At one point, about when I had
used
> the word "ACME" perhaps the fifth or sixth time in the conversation, he
said,
> "Where is this Acme firm located? I have never HEARD of it. Do they make
> anything other than lead-screws?" And he wasn't even embarrassed (or was
a
> skilled actor!) when I told him that was the common THREAD-TYPE of
lead-screw on
> manual lathes, etc.!
>
> Hope all this is of use to anyone who reads it! Jan Rowland
>
>
> [Non-text portions of this message have been removed]
>
>
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