RE: [CAD_CAM_EDM_DRO] Re: Backlash

Vince.

Are you still using the 1 thou DTI to show the start of movement like in the
video. My 1 thou DTI needs quite a lot of movement just to get it moving.

Have you tried you 1/10 thou DTI between the saddle and bed, back the screw
out one way until the DTI moves, then move the screw back in until the DTI
moves 1 thou, your back lash is given by the angle moved by the screw less 1
thou. Moving the screw by jogging with the CNC should give you this figure.







Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Vince Endter
Sent: 25 March 2007 16:12
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Backlash



The backlash is the same regardless of where in the travel the
ballscrew/nut is. For the backlash to be caused by flexing, the
ballscrew would have to deflect .215". I can garentee that the
ballscrew is not flexing that much. As for twisting, the pully in the
video rotates almost 4 degrees before the table starts to move. The
table takes about 40 pounds of pressure to get it moving and about 5
pounds to keep it moving. Hiwin said their ballscrew have a working
range well over 400 pounds.

Vince

>
> If you do the test with the screw fully extended and fully retracted
> can you not differentiate between flexing/twisting of the screw and
> flexing of the yoke. Maybe even extrapilate the error back to an
> effectively zero length screw to filter out ther screw error.
>
> Regards
> Phil

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