X motor stuttering

Hi I've been having a strange problem with a single axis on my machine, it doesn't move smoothly in one direction; sometimes it moves forwards, sometimes back, so that if I send to +1mm commands to the board, the carriage will stutter backwards or forwards, alternating at each command. I can also have it move in 10mm increments, again it will move 10mm forwards sometimes, sometimes 10mm back. I've switched the motor cables around, switched the motor drivers and even changed the pins.h configuration so that I now have my Y-axis driven by what was the E1 pins and the X by the Y. I've tried various different configurations but the issue seems bound to the X axis and does not seem to be a hardware/electronics problem (ie. when I switch the cables, the problem transfers to the new "X" motor, when I switched the pins, the problem stayed with the "X" motor etc.)
I'm using repetier-host v0.95f
edit: I just went to repetier and downloaded the new 1.00 RC2 software, it has the same issues.

Edited 1 time(s). Last edit at 07/22/2014 03:03PM by blabberjack.

That is definitively no host issue. It is firmware or hardware related.

As I understand you each command moves the right amount but direction is sometimes wrong, but only if motor is connected to the x axis position. That sounds like a hardware problem with the dir lane of your board or the stepper driver (have you switched the stepper driver as well to rule it out?). At the beginning of each move firmware the direction pin is set according to selected direction. And if that signal goes wrong you would get your problem.

So as a solution you could indeed use one of the extruder drivers for x axis.

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Hi, yes thats the issue, though when it is moving in the wrong direction, it misses steps. I've swapped the stepper drivers to rule them out.
The problem I'm having is that while the problem first presented with the X axis plugged into a driver on pins 54, 55, 38 (step, dir enable respectively). and Y on pins 60,61,56.
after changing them around several times, X is now on 36,34,30 (which was E0) and Y is in the original X position. However the stuttering is remains on the "X" axis according to the software- so for example if I flip the pins for X and Y, the Y axis will now stutter (though the host will now think the Y axis is the X axis) this is what I meant when I said the issue seems bound to the "X" axis- it doesnt seem to matter which motor, pin and driver combination I use, when I try to move X, it stutters.

Ok, that sounds more like a firmware problem. So first question is what firmware are you using and which version?

If that is really a firmware issue I'm wondering why you are the only one complaining, so perhaps it is something else we do not think of yet. Have you configured the motor pins to be used by something else (also I don't see why the error then should follow x axis).

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The reason I thought it might be firmware is that it seems to be something to do with the way the command to move X is handled, the hardware all seems fine.
I was originally using repetier v0.95F, but now have 100RC2
The firmware I'm using is older, possibly 0.71 I can't be sure since I renamed the folder. I'll try setting up newer firmware and see if that helps.
One thing that points to it maybe being a hardware issue is that everything was running fine and then a had to tighten the belts as there was wander during prints, after I had done this, the problem spontaneously appeared but I can't think of how it could present accross pins like it has.
edit: Maybe I should post my firmware to see if there is any obvious faults in it?

edit2: Just downloaded version 0.91, it has the same issues, still bound to X, I guess it must not be the firmware : (

Edited 2 time(s). Last edit at 07/23/2014 12:00PM by blabberjack.

The tightening of belts is the problem I guess. If it happened after it without firmware uploads there is no reason for firmware to be the problem. In such cases it is normally the last action before the error appeared, that is the reason. Could it be, that the motors now need more current to move and that causes the stepper drivers to disable due to overheating for short periods of time? This could increase friction in motors etc. Perhaps just loose belts completely and try again if they are back to running normal.

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Ok, now I am really stumped, I just replaced the ramps board (but not the arduino) and it kept happening! I've now replaced both boards, so new Ramps, new Mega and new stepper drivers and it is still a persistent issue! it doesn't make any sense!

edit: I hunted around with a logic probe as a last hope and found that two of my drivers had been dmaaged somehow, I think maybe something happened to the socket that originally controller the X axis and my swapping the drivers around eventually broke both of them, I've replaced the drivers and have them in the E1 slots and the Y slot and it seems to be running smoothly, I guess you can delete this thread since it wasn't really a repetier issue after all. Thanks for all your help though, I love this forum : )

Edited 1 time(s). Last edit at 07/23/2014 01:27PM by blabberjack.