Re: EMC .0001

Ian

I had the same screen manifistation, if not the same problem. I don't know
why I should be annoyed by a tenth of a thou -- most of the machine folk I
know would be happy with a bit more slop than that -- probably because it
shows up there on the screen.

If you're running Matt's 64step378.ini there is a .0010 backlash on X in
the stock version. I took out the backlash comp in the ini file and the
.0001 went away. I tried several runs of cds.ngc with MDI g0 x0 y0 z0 at
the end and it went back to .0000 every time.

Backlash comp is a quick and dirty mathematical/mechanical substitute for
no backlash. But it can do strange things for both the math and axis
travel. I had a control engineer explain it to me once over lunch but the
food and drink was much to good for me to remember much about the problem.

Ray Henry
From Michigan's (now beautiful and buggy) Upper Peninsula>

-----OM-----
From: "Ian W. Wright" <ian@...>

>Subject: Re: Aug-30-99 EMC release set free
>

>
>I tried both commanded and actual and get the same result although, as
>my machine will use stepper motors I would expect to use commanded
>values until I get a DRO set up. The reason I mentioned it is that it
>only seems to affect the 'x' axis and happens
>even when there is nothing connected to the port. If the resolution is
>reduced to 0.0100 per step or less, it seems to correct itself but, for
>anything finer than this it seems I would have to home it then change
>resolution to 0.0001 and jog the axis to exact zero manually. As the
>other axes don't exhibit the same effect I thought it was probably a
>minor software problem but it may, of course, just be an anomaly with my
>machine. I expect other users could comment on this. Also, is it normal
>for the digits on the screen to noticeably flicker as a g-code script
>runs? I assume it is a factor of the refresh rate but wonder if it could
>be stabilised in future developments. I noticed your comments on 4-axis+
>use of EMC in another post and didn't understand a word of it! Since I
>will need at least 4 axes, is there any chance you could do a kind of
>short 'idiots guide' to setting this up please - I'm sure others on the
>list would also be very grateful for this. Thanks,