Re: [Emc-developers] A clue..

[Jon E. <el...@pi...>]

Maxime Lemonnier wrote:
> Thinking to it.. the only clue I have is that the error is always in the
> same direction : the z-column always tend to move higher than it should.
>
> Fo the moment I guess the machine is usable for milling. I will limit z
> acceleration (ah it could be a nice way to find out if it the problem is
> mechanical or electronical : reduce the acceleration!)
>   
Acceleration REALLY shouldn't have any effect, even with a bad encoder.
But, yes, it may be helpful in isolating the problem.

OK, now that you've determined the shift is always in the same direction 
is interesting!
Encoders that have something wrong with their quadrature phase 
relationship often
lose counts in one direction more than the other.  I would remove the 
encoder and
reinstall with their centering procedure.  Incorrect centering of the 
read head could
cause this sort of problem.
> I know the problem is possibly not related to your product, and I'm very
> thankful that you help me out.
>
> One day I hope I can "pay back" and help you with anything (Software?).
>   
Likely you can't help ME, directly, but if you want to contribute to the 
EMC project,
that would be great.  There are MANY areas where we could expand the 
features of
it.

At some point, I am hoping to port EMC2 to the "Beagle Board", an 
open-source
CPU all on a single 3" x 3" PCB.  With a few accessories it runs about 
US $200.
At present there is no real time kernel for it, but it does run Linux 
quite nicely.
I provided a Beagle Board to one of the RTAI folks, and hope in a month or
two he can get a RT kernel running.  I will be getting a PCB back from the
fabricator shortly that will adapt a parallel port to the Beagle.  So, 
that is my
crazy development project for this winter.

Jon