Laser head walking off

[Jordan Lavely]

Hello, I'm having a problem with my epilog legend 36ext. Laser head is walking to the left while rastering at any speed. Home position is off to the left after running also. When running vector there are lines that are not connecting and placement of interior parts of a design will sometimes be pretty off. I have replaced the encoder strip and strip reader on the x axis. Also have replaced the flex cable from strip reader and the x axis belt. I've oiled everything I can think of. The gantry is straight. I have cleaned everything I can think of. Put a call into epilog support and the guy believes it might be the x axis motor. I'm not saying he is wrong but I'm not convinced enough to spend 800 on the replacement motor yet. The motor seems to be moving the laser head just fine. It seems like a placement problem. I'm far from an expert on this stuff so I'm wondering if there is any "reprogramming" that needs to be done after replacing the encoder strip. I looked at the manual and could find any good information about it. I would post pictures but I can't figure out how to on this forum. Any help is absolutely greatly appreciated. And please forgive me for my lack of knowledge on technical terms.

[Bill George]

Tighten the motor pulley set screw

[Jordan Lavely]

I forgot to mention that I did that as well to no avail.

[Kev Williams]

My GCC Explorer has servo YX motors, however, the encoders are 'clear' disks mounted to the servo motor shafts, which pass thru a slot on the readers--
498039

--closeup of the hash marks that are counted, and note
this disk is filthy! It was off the machine due to the same exact
problem you're having, kept walking LEFT--
498040

This was what the disk looked like after I cleaned it, all the black guck gone
and the perimeter of the disk pretty much transparent-
498041

--I don't know if gantry encoder strips are hash-marked like this disk, but I assume so.
But one thing is for sure, the strip or disk must be within a certain distance from the reader
so the reader can count the marks, aka an air gap, and typical is .002"...
So will all else being up to snuff, there's only 2 reasons I can think of that a reader will fail
to read an encoder--
--either the encoder has crud or something else on it 'hiding' the marks from the reader,
-or-
--the distance between the reader and the strips to be read is too far...

Since I don't know what an encoder strip or it's reader looks like, or how they're mounted,
but is it possible your air gap is 'growing' for some reason, towards the left side of the machine?

[Jordan Lavely]

You know what, that gives definitely gives me something to look into.
First of all, I replaced that strip and cleaned it. And it is hash marked. I don't know how to explain this well but the reader is held on by 2 screws. A while ago it got stripped. I tapped the the threads to a slightly larger size. But I wonder if there's any chance that when I widened the holes on the reader that they weren't centered properly. I used the old holes of course and just widened. But if the tolerance is that close I could see it moving a little.
Also I just found that one of the x axis idlers was shot. I replaced that yesterday. It is walking off very very little now but still some. And the home position will reset at the end of the job to the left but about 4 inches. Incase that information helps any.

[Kev Williams]

One test you can try, set up some engraving on the extreme right edge of your table, just engrave some text, or a bunch of vertical lines, like: |||||||||||| - across the last 4" of X travel, and check for walking--

IF it still walks left when engraving from the extreme right, something else may be going on; this experiment would hopefully figure out if the problem is limited to the left side. If it walks left pretty much same anywhere you're working in the X axis, could be the entire strip-to-reader gap may be a bit too much-- but if it only walks when being used on the left side, could be that screw or something similar causing a mis-read only in the area of the loose screw...

What interests me is that it's only walking LEFT, but that's what mine did too, with a totally different encoder/reader system... ?

[Mike Null]

FYI
Several years ago Epilog had a serious X axis motor issue which they dragged their feet on resolving. My recollection was that they had used a motor too small for the job. IN fairness, even though they took their time, I believe they resolved all their customer issues.