Model shifting mid print

Skipping steps! Could be mechanical binding (probably) or electrical. Lots of troubleshooting posted so far, search around a bit.

also check your endstop...

the last time i had this problem, it was a short-cut on one cable of the endstop of the x carriage. (i redo the solder point on the endstop switch to correct the problem and replug all endstop connector)

during the print, the switch send false information that the head touch the endstop, and the print shift because the printer think that the head is not where it think it is..

When you slide the Y axis back and forth, is the motion smooth, or are there any points along the way where there is a little more resistance?  The drive rod on mine is bent slightly, so with every revolution there is a point where it has to push a little harder.  There might still be a mechanical issue that is at a point in the Y axis that the circle didn't reach, but the star does.   If there is a sticking point, the motor belt might be tight enough to bind it there.

The voltage on the driver being off is another possibility, so that is worth checking as well.

Still no luck.....

the y-axis seems really smooth when I move it by hand, and the rods seems straight.  I also checked the connection on the end stop, it looked fine but I re-soldered it anyways because I had all the tools ready.  Sadly, this didn't do anything. 

Ian I think next I will check the drive motor, any advice on where to start with that?  I'm also going to buy some lube and just make sure the carriage is gliding smooth.  But after that I am fresh out of ideas.

Finally the holiday break is over and I can try to fix this thing again!!

So I have been trouble shooting with all the suggestions from everyone, but nothing is working.  So I recorded a print.  The printer stalls, or gets caught while traveling on the y-plane, but I can’t seem to tell if it’s binding somewhere or if the motor isn’t getting enough juice or what.

Check out the video if you have a minute, the first time it skips is at 2:40, but really just skip to minute 5 and watch.  It skips at 5:03, 5:24, 5:36, 5:46, 5:55, 6:05….. it actually skips 31 times in the 9 minute video.  I couldn't get the video to upload here so I put it on YouTube.  I don't have permission to add links yet but its here:

youtube.com/watch?v=yN78VY8Nrcg

I just borrowed a buddies voltmeter so I am about to check the motor.  I have looked around and I can’t find anything about what amps/volts I should be reading.  So if anyone knows please don’t hold out on me!!

Thanks again everyone.

The stepper motor will be drawing the same amount of current, dependent on that voltage setting, irrespective of the friction.

I watched the video and am not sure what's going on... Are your Y-axis sliders in alignment?

You might try to add some additional load with your hand (be careful you shouldn't need much) with the manual move controls in pronterface, just move the printhead back an forward with your hand giving some drag then do the same left and right just to give you an idea of how much force is required to make the motors lose steps after you have done this with your hand on the printhead then do the same on either end of the x axis, if the axis is slipping out of alignment you should feel it on one side and it is most likely the drive gears on one side slipping against the shaft.

edit: just do small moves and keep an eye on where the head is so you don't get pinched :0

It worked!!  So I followed the instructions on the troubleshooting section on Solidoodles site and played Operation with the motherboard.  The voltage for the y motor was set to .48, and I adjusted it to the recommended .52  per the instructions.  I successfully completed 2 prints without the stalling I was experiencing, which was somewhere around an hour of trouble free printing.  I started off with an easy print of a money clip, and by the time it finished I felt a hundered times better than those  2 dollars I shoved in it.  (Picture attached)

Then I moved on to an X-wing starship and got a little more light saber than spaceship if ya know what I mean…. Seriously though, look at the pic its hard to miss.  But now that I can complete a print I can start messing around with the settings to get these to come out better.  I did actually run into another problem though, I was printing the Yoda bust (this is all coincidence, I’m not a Star Wars nerd…. Well I guess deep down who isn’t though right?)  and a half hour into the print it just stopped printing.  No warning, no weird noises or anything, it just froze up.  So I tried it again and the same thing happened (not at the same spot though).  I’m going to search around and see if this has happened to anyone else, but if you have any advice on that feel free to comment, otherwise Thanks again everyone!!

Fixed it, I have.

Seriously this printer is awesome.  I made it through my first 2 hour (ish) print, and I saw a lot of people were following this topic so I thought I would add the happy ending and show my yoda print.