Re: [CAD_CAM_EDM_DRO] EMC problem/question

Hi Hugh,

Check the axis offsets - look at the little figures in the top right of the
window. I came across a similar problem after a new install of EMC. There is
a file of offsets under the 'scripts'(?) menu which has loads of entries
normally set to '0.00000', you may find one of these has set itself to 0.010
or something - if so, just set it back to '0' and try again.

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk

----- Original Message -----
From: "Hugh & Denise Currin" <currinh@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 04 August 2001 13:21
Subject: [CAD_CAM_EDM_DRO] EMC problem/question


> Crew:
>
> I am having a problem with EMC and don't know where to go from here. I am
> hoping someone more familiar with EMC can direct me.
>
> I've noticed my mill doesn't come back to zero after a number of moves.
If
> I repeat
>
> g01 x0.1 f10
> g01 x0.0
>
> twenty times in a program the zero is off by 0.010". If I change the
> distance moved from 0.1" to 0.2" I get the same error, .010. I can do the
> same with moves in the y direction. Double the moves (40) gives double
the
> error 0.020". I changed the feed rate to F5 and the errors are the
> same. I changed the default and maximum accelerations in the .ini file
> from 10 to 5 with no effect. Finally I wrote a program with
>
> g02 x0.2 y0.0 i0.1 j0.0 f5
> g02 x0.0 y0.0 i-0.1 j0.0
>
> a circle of 0.2" diameter, repeated ten times. This gave a final offset
> error of .005" in both x and y. Finally I did this last again using
> g03. The errors were the same and in the same direction (+ reading on DRO
> in all cases). I did a small move from and to zero to eliminate any
> backlash as:
>
> g01 x.05 y.05 f5
> g01 x0.0 y0.0
>
> I have a hard time believing this is mechanical since it happens to the
> same degree in the x and y directions. Likewise the stepper motors and
> drivers are separate for the x and y, leading me to believe the problem is
> not there. That leaves the software EMC.
>
> I am running Red Hat linux (2.2.14), rtlinux 2.2 and the Aug 11, 2000 EMC
> on a 450 MHz P3 with 64M. The drivers are 5A Camtronics running half step
> to steppers of about 750 oz-in. These connect to ballscrews through 2:1
> timing belts on a 9x42 knee mill.
>
> Any ideas or suggested tests?
>
> Thanks.
>
> Hugh Currin
> Klamath Falls, OR
>
>
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