Weird X axis problem

[Matthew Berry]

Today I created my first "real" project on my newly constructed Gatton CNC - it was a box with 4 sides and a top and joints/pockets between them.  The gcode ended up being a first part that cut the 8 pockets in the top - this worked fine.  The next part was to cut the pockets in the sides - when the router moved to cut the first pocket there, the X axis stopped moving.  I quickly did a Feed Stop in Mach3 and at that point I was not able to manually jog the X axis, but after waiting a few seconds, I was able to jog.

At this point, I figured I had nothing to lose, so I reset the router to the start position and then started over.  It cut air for the pockets in the top and then when it started to cut the first side pocket it seemed to get a little further, but again the X axis stopped moving.  Again I did a Feed Stop and could not jog the X axis for a few seconds, but then I could.

This time I edited the gcode to start with the side pockets, reset everything and restarted.  This time it cut the side pockets just fine.

The next thing in the gcode was to do the contours around all the parts.  You guessed it - the X axis stopped moving.

At this point, I created separate code files for the contours around each of the parts.  I was able to run each of those files in turn without any further issues.

Does anyone have any clue about what is going on?

Note:

1) I posted this into the Gatton CNC forum as well

2) I did read the other post here about someone skipping steps on the X axis, so I am going to try some of the steps suggested there.

[Danny Giesbrecht]

Check that the wires in the plugs to the motors are firmly in place. Mine one wire which happened to be the power wire came loose which causes a spark that I saw so I knew the problem right away. I'm not sure why there are 4 wires but maybe some are data wires and if they come loose the motor wouldn't turn but there may not be a spark

[Matthew Berry]

Hi Danny:

Thanks for the response. I ran everything again tonight without the router running which allowed me to actually hear what was going on. When I get the problem, I can actually hear the xaxid motor go quiet (even though it should be moving according to Mach 3). At this point if I do a feed stop I can't jog the x axis and I can actually turn the lead screw by hand. If I wait a little while I actually hear the "thunk" of the x axis stepper and at this point things are back to normal. I have checked the connections and I don't think the symptoms quite fit a loose connection. I'm starting to think that it is a thermal problem. I'm going to try again in the morning when things are cooler!

[Matthew Berry]

I have just rerun things when the temperature is 64°F instead of 89°F.  Also note I am running in air without cutting anything.  I was congratulating myself because it passed the point at which I had problems before (and the motors were warm to the touch, not hot), but that proved to be premature because a bit further on the X axis stopped working again.  Having tried all the obvious things at this point (e.g. unplugging and replugging all the motor connections, checking the connections between the parallel cable and the controller and between the UC100, lubing all the lead screws, checking all the v bearings adjustments, etc), I decided to try the suggestion from another post here and that was to try switching motor cables.  

I decided to try switching the X and Z cables because I didn't want my gantry to get skewed if one of the Y/A motors stopped.  So, I took the Red cable from the X axis and plugged it into the Z axis motor and then took the Green cable from the Z axis and plugged it into the X axis motor.  I then switched the output pin assignments in Mach 3 (X became 6/7 and Z became 2/3).  Checked I could jog in the right directions and then restarted the job.

At pretty much the same point (which is about 15 minutes into a 30 minute job) the Z axis stopped working with exactly the same symptoms as previously on the X axis i.e. it stopped moving as the job was running and, when I did a Feed Stop, I could jog the other axes, but not the Z.  Waited a little while and then heard the "thunk" of the Z stepper (like when you first turn on the controller) and I could then jog it as normal.

As a final step, as I am using extension cables on all my axes I decided to just switch the extensions that were on the X and Z axes.  This had the same result as above.

Any suggestions are truly welcome!