Re: Ballscrew mounting

Sounds like a good plan, Joel. I never considered drilling the ballscrew
and inserting another piece with the features already turned on it. The
darn screw is so hard it would be very difficult to turn and thread it.
Great idea! Question: what do you plan to drill the screw end with? I
tried it tonight on a scrap piece of ballscrew and even using a HSS stub
bit the hole was still slightly off center. It just didn't want to bite. The
point at which the tip of the bit hits the material seems to be the
critical issue. If it walks at all any other drilling will be off...

FWIW, I've taken apart the table and reassembled it. The Y axis is
mounted exactly the same as the X except the end of the lead screw is
just floating in space. The tricky part is reassembling the nuts - you have
to plan ahead :)

Good luck. I'll post pictures of my progress on my website one of these
days.

http://www.swayze.org/shop

-Jeff

--- In CAD_CAM_EDM_DRO@y..., "Joel Jacobs" <jj@n...> wrote:
> 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