Re: [CAD_CAM_EDM_DRO] Ballscrew mounting

Hi Jeff,
I'm in about the same place with my mill/drill and I'll share my ideas for
the conversion with you. I got 48" of .75 X .200 screw from McMaster-Carr.
The thrust bearings on both axis will be just two stacked 5/8id deep groove
ball bearings with shims between the inner races. I will make new end
blocks to house the bearings and clamp the outer races. I will machine stub
shafts with a shoulder and threaded portion to fit the bearings. I will
attach the stubs to the screw by drilling about a 1" x .375 or .5" hole in
the end of the screws and a machining the stub for a slip fit and use 271
loctite to secure. The y axis will only be secured at one end. The x axis
will have these thrust bearings only at one end with the other (motor) end
exiting through a single ball bearing. With the thrust bearings oppisate
the motor end I will be able to fiddle with the shims without removing the
motor.
For mounting the nuts - On the x axis I'll make a block about 1" thick,
bore a hole in it and thread it to fit the nuts and thread a nut in each end
so there will be two nuts. I'll slot the block and put a bolt through so I
can clamp the nuts from turning after I get them adjusted.
I haven't figured out the y nut mounting yet because I can't see in there
very good. I need to take the machine apart and get some ideas. I do have
a single circuit nut that I was lucky to get with not more than .001 lash
and I'll use it on the y. I won't need to double nut that one. I may get
some half thou oversized balls and polish the screw till I get a real nice
fit.

Wish me luck!

Joel

----- Original Message -----
From: Jeff Swayze <jswayze@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, March 17, 2001 10:01 PM
Subject: [CAD_CAM_EDM_DRO] Ballscrew mounting


> Hi Folks,
>
> I've assembled nearly everything I need to implement my mill/drill CNC
> conversion, but I'd like to draw on the experience of this group to find a
> solution for mounting the ball screws. I've got the Harbor Freight version
> of the RF30 mill/drill - you can see pictures on my website
> (http://www.swayze.org.shop/ ).
>
> Y-Axis:
> I've disassembled the table and found that the leadscrew has no
> mounting on the far end - just a thrust bearing at the handle. My original
> plan was to provide bearings at both ends, but now I'm considering
> putting bearings just at the front and letting the rear hang freely. Even
if
> the saddle is cranked forward as far as it can go, the ball nut will still
be
> in the center of the ball screw. How have others approached this?
>
> X-Axis:
> Since this ball screw is so long (approx. 36") I'm going to support both
> ends with dual linear contact bearings, each separated by 3/4" or so.
> Though the information was tough to come by, I found some info on how
> to configure the linear contact bearings on the web.
>
> In general, have others removed the existing mounting brackets and
> simply made a new housing using the existing mounting holes? Is it
> possible to rework the mounting flanges already present? I've seen a
> couple of pictures of people using the 3" square steel tubing to mount
> the motors, but it seems like once it was bolted to the saddle/table
> there would be no room for the bearings. Pointers?
>
> Sorry if I rambled a bit, but I'm having a hard time getting my arms
> around the whole mounting issue. Any help would be greatly
> appreciated.
>
> Thanks,
> Jeff
>
>
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