Re: [CAD_CAM_EDM_DRO]Screw drive

At 15:51 29/03/2003 +0000, you wrote:

>I too am perplexed at what the thing looks like, but I guess that the
>three screws are set so the heads act like threads in the larger
>leadscrew.
>
>Since I didn't see any reference to bearings, the unit would wear
>quickly.
>
>Dave

Dave -

Its hard to visualize without a diagram or pic, so take a look at this:

http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/Tony%27s%20files/screw%20drive.JPG

There are three short lengths of threaded rod (they don't have heads!)
arranged in a triangle around the leadscrew. Each of the short rods run in
needle roller bearings & have thrust bearings at each end (as Alex has
indicated, the latter could possibly be plain bushings, although the
article talks of using cheap plastic caged ball races). The top screw is
adjustable to take out any slack between the leadscrew & the "screw nut".


Regards,
Tony