Odd problem with my Y axis travel.

Longboat Prusa using Pronterface.

I am troubleshooting why I am getting some dodgy prints.

Using Pronterface I can click on the +Y 100mm travel and it works super. If I click on the -Y travel then I get problems. Most of the time it doesnt travel the full 100mm, sometimes nowhere near 100mm and yes I am definately not clicking the 10mm feed by mistake . +Y 100mm travel works 100% of the time and -Y 100mm travel works less than 10% I would say.

I can use the shorter 10mm travel and both directions work 100%. I can shuttle to and fro counting the number of times I press the buttons and it all works tickety boo with 10mm travel.

I have checked that the belt is ok. I didnt think this would be the problem because it doesnt seem to attempt to travel the full 100mm.

I have changed the current on the pololu driver current and the problem is consistent.

I have checked the freedom of the Y axis movement in both directions manually with the power off and it is fine. It is definately not sticking anywhere along its travel.

I have swapped the X axis connection on the board with Y axis so when I click on +Y the X axis moves and the problem is still there. Works fine in the +X 100mm travel but not in the -X 100mm travel.

I did think it could be a duff motor but I am thinking maybe duff Pololu driver?

well if you swapped x and y that would have used a different pololu.

Sounds like false triggering of the end stop.

Are your motor and end stop wires running together?

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[www.hydraraptor.blogspot.com]

se5a Wrote:
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> well if you swapped x and y that would have used a
> different pololu.

Ah yes but it was then the X-axis travel that was incorrect. Sorry this probably wasnt clear.

Anyway, I have tried with different Sanguinololu board, new end stop wires and the problem is still there!!
It is not causing an issue with my prints I dont think as it is only the 100mm travel.
Bizzare really. It isnt the Pololu drivers as it happens using different ones. It isnt the motor as I can get it to happen on the x axis as well.
It isnt the end stops.
So what can it be? I can only think it is some problem with Pronterface. Something odd with my installation or something.

No resolution but as I say not really impacting on general printing so leaving it alone for now.

Are you sure your pulley is not loose?

Besides stepper skiping steps a sliding shaft may cause weird results too.