TAZ 5 Calibration off

I’m hoping someone might be able to point me in the right direction on this one.

I have a TAZ 5 that has been working flawlessly for the last several months. Recently halfway through a print it started to ‘shift’ the print to one side, almost as if the print had been moved on the bed midway through. Since then it has not been able to reliably print anything. When I run the configuration STL file I get what you see in the picture below.

All of the belts appear to be taught. I have reloaded the firmware (2015Q2), verified the X,Y,Z,E steps are all correct. Any suggestions would be appreciated.

Check the x axis motor pulley setscrew. If that is loose, it can still shift like that even with a taut belt. If it’s not that, check the fan on your Rambo boars and the x motor cables. But it’s most likely the pulley.

Hi Piercet,

Thanks for the suggestion. Set screws are tight. At first I thought they were missing, but I was using the wrong size allen wrench. Motor connections all appear to be good. Not sure about your comment regarding the Rambo board fan. It does come on periodically, but I don’t see how the fan would have anything to do with this.

After some further experimentation, whatever is going on appears to be related to the x-axis. Just tried printing a rectangle oriented along the x-axis (left to right). Each subsequent layer printed further to the left. Y-axis orientation looked good, there was no shifting.

If the x axis motor controller chip is overheating. It will stutter and move irratically.

You could possibly have an x steps value off in firmware. It should be identical to your y steps.

X and Y steps are both at 100.5 which matches the Test/Acceptance record. I don’t think it is overheating since it happens now on every print, starting from the first layer. When I printed the rectangles, the ‘march’ to the left was very deliberate. As near as I could tell they appeared to be in equal steps, shifting about 2mm to the left with each layer.

That’s exactly what I would expect to see with s loose belt or pulley, but you checked those, so, it’s got to be electrical or maybe a really gummed up rod bearing.

One last question. If I move the x-axis carriage by hand, shouldn’t it move fairly smoothly? Mine is not. It’s definitely tough to move, and not consistent in the amount of pressure needed. Definitely harder to move than the bed on the y-axis. I’m thinking that might point to either the bearings or the stepper motor.

Calling it a night. I’ve triple checked the pulley, it’s definitely not slipping. As far as I can tell I don’t think the belt is jumping over any teeth either. Have also tried printing at different locations on the bed to see if there was some issue with the rods themselves.

Anyway, thanks for all of your help tonight. Much appreciated. Maybe a fresh set of eyes tomorrow will find something.

Sounds like a bad motor shaft.

Ding Ding Ding. Kmanley you get the prize. Josef at Lulzbot emailed me and had me take off the belt. Motor pulley AND shaft came right out of the motor.

Thanks to all of you for your help and suggestions.