Re: rigid coupling, stepper to leadscrew

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <eexgs@...>
wrote:

>
> Again on the subject of the KT150 table conversion:
>
> http://www.indoor.flyer.co.uk/kt150conversion.htm
>
> I was wondering exactly how bad an idea coupling the leadscrews (2mm
> pitch 10mm diameter ACME) directly to the screws would be?
>
> The screws are unsupported at the other end.
>
> Obviously the motors would take end loads but they have bigger
> bearings than I would use for thrust bearings even on the small ones I
> have, they are also dirt cheap. Endplay is had to detect but then I'm
> only pulling and pushing on them by hand.
>
> Alteratively what is the shortest and thinnest method of adding a
> bearing to the end of a screw? I'm considering two thrust bearings
> and a needle roller to make the machining super simple (just one hole
> for the needle roller).
>
> Graham

I'm not sure I follow the question.

to fix one end, and not use a dual angular contact bearing to
eleminate axial movement, you could use other things.

A pair of standard ball bearings, mounted in a block, seperated by
wall would do a lot.

a screw on the end of the shaft would squeeze both bearings and get
the balls to ride slightly on the sides of the races.

these are not as stong as angular contact bearings, but can handle
some pretty decent loads.

the wall needs to be ridgid as that is the one constant location.

To make the end short, you can tap the screw and use a button head
screw, or even a flat head. Adjust the screw inside of the leadscrew
to pre-load the bearings.

Dave

>