Re: Is this an unreported bug in EMC?

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Clint Bach wrote:

> Soooo.....  What are some of those rather disturbing bugs in TKEMC?  If
> I know about them maybe I won't be so alarmed when they bite me!

Well, there is really only one that has me worried.  I was cleaning up an edge,
and entering this sort of sequence in MDI.
Y-.02
X17.25 F10
Y0
X0 F45
and then repeating it with a slightly different Y, until the edge was cleaned up.
On 3 occasions, when I entered the Y-.02, I got a long move in the +X
direction, probably with slow motion in the -Y.  I suspect it was going to
X17.25 Y-.02.  This looks more and more like the phantom axis move
problem we had about 6-9 months ago, now that I describe it again.
That was fixed by Fred Proctor about July 1999, if I remember, maybe
even earlier.  I was hoping to never see that one again, but I fear it
has come back.  (It used to be a pretty solid, reproducible problem,
that when you entered a move in one axis only, then maybe flipped from
MDI to manual and back (aborting the move), and then entered a move
in a different axis, it would keep the first axis go-to point (because it
never 'got' there), and then combine both coordinates, making it into
a 2-axis move.

I may have done this, although I don't specifically remember aborting
the move 3 times, I'm pretty sure I did it at least once.  I think aborting
the move was necessary to cause the bug previously.  I will have to
test this sequence to see if I can come up with a script to induce the
error.

Anyway, I used TkEmc again tonight, and had no problem with it.
Other than the above, there are just a few very small quibbles with the user
interface, itself.  And, those should be fairly easy to change.

> I sure wish there were individual maximum speeds for each axis in EMC
> like with AHHA.  On my machine I have about 1000 steps per inch on x and
> y and about 3760 steps per inch on z.  It's a shame to have to slow x
> and y down that much...  Especially since z rarely travels very far at a
> time.  Oh Well.

Well, this is a stepper limitation, really.  I wouldn't have that limitation
on my system, for instance.  But, when combining rotary and linear
axes, it looks like it could become a very big problem, indeed.

Jon