Re: Ball Screw Options

Message: 6
Date: Thu, 14 Nov 2002 21:47:30 -0800 (PST)
From: Jim Brown <jagco1998@...>
Subject: Re: Re: Ball Screw Options


Reidtool.com has a decent selection of Nook and Thomson ballscrew for a fair
price,though Mcmaster has a larger selection of course.
And Ebay usually has a guy on there selling complete X and Y assemblies for
Bridgeports for aroung $800.00

Hi Mark-

[I've gotten Bridgeport parts from High Quality Tools. They came through
with a clockspring for the quill after I struck out with Bridgeport itself.
They sell a "drop-in" preloaded x-y ballscrew assembly for $650, which is as
cheap as I've seen. See: http://www.hqtinc.com/accessories_b.cfm#ballscrews
These only fit the standard 42" and 48" tables, though- I guess you'd have
to cut one off for the 32" machine you've got. They recommend using two sets
of their #1173A precision bearings to install them (at $85.55 per set),
which makes the project more expensive- but you got such a good deal on this
machine, you've got money to blow, right?]

Ballscrews for a machine of that size is not really going to be cheap to
begin with.
You get what you pay for. If you want accuracy and repeatability, youre
going to have to pay the price.
You can make preloaded nuts for your existing leadscrews, but they will not
hold tolerance very long, and you will be adjusting them quite often, and
soon be replacing them if used daily. But with ballscrews, if you get a
preloaded set or make your own preloads by buying 2 cheaper ballnuts and
preloading them, the only lead error you have to worry about will be the
lead error on the threads of the screw(usually around 0.0005"/ft and varies
with manufacturer).
Youll probably get another mill before they fail on you, provided you keep
them properly lubricated and clean of debris.

[High Quality Tools also sells Goretite way covers for Bridgeports- probably
a good investment, if you get the ballscrews.]

If money is your concern then you are definately in the wrong
arena...........very very expensive little hobby we have!
Regards,
Jim

>
> ----- Original Message -----
> From: "natchamp_87"
> To:
> Sent: Thursday, November 14, 2002 8:38 PM
> Subject: [CAD_CAM_EDM_DRO] Ball Screw Options
>
>
> > Well, I've taken the plunge and purchased my mill for the CNC
> > retrofit. I bought an older Bridgeport with an M head. It has a
> > 9x32 work table and its perfect for me because I get the full 12"

Y

> > travel but the overall machine will fit in my garage much better

than

> > a full 9x42.
> >
> > Amoung other things, I'm trying to resolve is what I'm going to do
> > for the ballscrews. I would really like input on what my options
> > are. I've looked into the archives and am starting to get the

angle

> > of the dangle.
> >
> > 1) Is one option to install anti-backlash nuts on the existing

stock

> > screws? I've read about making/installing anti-backlass nuts but
> > can't figure out if that applys only to ballscrews.
> >
> > 2) If I were to install new ballscrews and nuts what specs should

I

> > look for? Is 5 tpi the standard? How about the diameter?
> >
> > 3) If I do #2 above am I right in that I have 2 options, either

buy a

> > bolt in kit or buy the ballscrews and fabricate how the nuts

attach

> > to the table?
> >
> > 4) What do I have to do/consider for attaching the ends to my
> > servo/stepper motors? Do I have to do any machining to them for

this?

[I believe the ends of the kit ballscrews are ready to accept the bearings.
However, if you need to cut one off, machining the end will be a problem,
since it's difficult to remove the screw for machining without losing the
balls. If there were some sort of giant pencil-sharpener you could stick the
end into to grind it down to size, that would be best...]

> >
> > I came across Nook Industries www.nookind.com. Has anyone used
> > these? Are they the most cost effective ones? Is there such a

thing

> > as a cost effective bolt in? The only price I've seen is in

McMaster

> > Carr for @800 buckies. I sure wish I could do it for less. Any

help

> > greatly appreciated!
> >
> > Mark took the plunge

[Did MMC have a 32" model, or would you have the same problem with their
kit? Does it include the bearings?]

Andrew Werby
www.computersculpture.com

> >