On Sun, 2009-04-26 at 10:54 +0200, [email protected] wrote:
> Hello to the List, I'm Fabio from Italy.
> Sorry for my pooor english:)
> I'm building a nc mill machine together with a
> pair of friends. Motors on 3 axis are steppers,
> drivers are MD542, interface is parallel port.
> I have mounted encoders on
> steppers to stop the machine on following errors
> and it works. Now i'm dealing with homing process.
> I'd like to do home on index of encoders, but i'm
> having following errors. Home switches are NC, in
> series and I perform homing axis per axis.
> Conventional homing is fine, if I activate home on index
> I have following error on the axis being homed.
> For example on z I have home at 180mm, home offset at
> 190 search vel 5mm/s latch vel -.2 final vel -2,
> rapids are 16. Tried also final vel 2.
> If I raise ferror and min ferror to 100mm I don't
> have following error but behaviour is strange:
> the axis goes to switch at search speed, then goes
> down off switch at latch speed, then for some reason
> accelerates axis to some high speed for about half a
> second and finally goes to (wrong) home position at
> final speed. Since the machine is about 30km away
> now I'm testing motors on my bench and I'm activating
> home switch by hand.
> I don't want to write a huge message, how can I attach
> my seutup files?
> Thanks, Fabio.

Halscope can be useful in trouble shooting homing and other problems.
http://www.linuxcnc.org/docs/devel/html/hal_tutorial.html#sec:Tutorial%
20-%20Halscope
(short URL) http://alturl.com/k4if

You can connect the home switch, index and encoder position signals, to
see what happens, and when. Then you can compare this to the
documentation here:
http://www.linuxcnc.org/docview/html//config_ini_homing.html#fig:motion-homing-sequence-diagram
(short URL) http://alturl.com/zja4

You can also pastebin the Halscope traces using (from the desktop)
"Applications / Accessories / Take Screenshot".

-- 
Kirk Wallace
http://www.wallacecompany.com/machine_shop/
http://www.wallacecompany.com/E45/index.html
California, USA


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