Re: [CAD_CAM_EDM_DRO] re:Re: Ball screws for CNC plasma cutters

Apparently we see the construction of the part differently based on the
description given.
Perhaps the original author shouold get byusy and post a couple of cross
section views of what he's describing so we'll all be able to visualize the
same thing.

>The problem with the "spring between" method you propose is as he
>mentioned... Any pressure applied greater than the spring will
>introduce backlash. To reduce this tendency, the spring is made
>stiffer. Problem then is, the spring causes the nut assy. to be hard
>to turn and adds undue wear of the screw. That is why this type of
>backlash screw is seen less and less today...

Good point!

>
>What he proposes (although I'm not sure I see it the way you
>described) takes advantage of the pressure angle of the acme screw
>that I just talked about (earlier post). That is, since the pressure
>to "close" the two halves of the split nut is applied at right angles
>to the screw, the flank angle will HELP us to get more EFFECT from a
>lighter spring pressure. Also, the axial load will again be helped by
>this flank angle (with a 10 degree angle,only a small percent of the
>force is being directed in an effort to "push the split nut apart").
>Yes, these last two sentences say the same thing; from different
>directions.
>
>The method is also easily adjusted, allows for wear, and is easily
>changed for ballscrews later(you just mount the outer cylinder to the
>machine in the same way as the ballnut ; i.e., a threaded end, or a
>mounting flange.

The split nut assembly will STILL be larger in diameter than the space I
have available for it!

Smoke

>Ballendo