Print layers moving on one axis during print

[richardy 0]

Hi,

We have an ultimaker 2+ printer that is having print issues related to the print layers shifting during the print in one axis only (see attached pictures). The layers are shifting toward the front of the ultimaker but sometimes they shift back and forth (see pictures). This issue is also not consistent - sometimes it will print a model correctly;y.

 

The models print correctly on our other printer (Lulzbot Taz 6) but we would prefer to print on the Ultimaker for certain print jobs.

 

What could be causing this? Firmware? the guide rails are regularly lubricated.

 

Any help is much appreciated.

 

Cheers.

[geert_2 558]

Maybe one of the hex screws getting lose, and that gear slipping over its rod?

 

Or else there is too much friction in that direction, so the stepper motor skips steps? With the machine off, move the head around by hand: it should go smoothly in all directions, without requiring brute force.

[gr5 2,210]

What geert_2 said.

 

Add a drop of oil to the 4 large and 2 thin rods.

 

But more likely the problem is you need to tighten the set screws on the pulleys.  It looks like the Y axis so only work on those.  It's almost always the screw on the stepper motor itself.  You can get to that screw without taking anything apart if you move the head around by hand until the screw lines up and using a long hex driver to get down in there. 

 

Tighten the hell out of that set screw!  Much tighter than you would think is necessary.  If you were to use a little L shaped allen wrench it will hurt your fingers to get to the proper torque.  The wrench should actually twist slightly!  It's a lot of force.

[richardy 0]

HI,

And thanks for the replies much appreciated.

 

I already regularly lubricate the 6 guide rods so i dont think this is the issue as moving the head is very easy with little effort.

 

I have tightened the pulley wheel belt set screws for the y-axis - connected to the stepper motor on the left hand side of the ultimaker at the back of the machine (when looking from the front)? I noticed that when i tightened the set screw on the belt pulley wheel on the stepper motor itself, it then become very difficult to move the head in the y-axis direction. Does this suggest a partially seized Y-axis stepper motor? This would explain a lot.

 

Any help is much appreciated.

 

Cheers.

[minercraftal 0]

Could it be a bad board, gave the wrong information or sometimes don’t lock the motor makes that big steps... well I’m not so experienced 

[gr5 2,210]

It's unlikely to be the stepper motor but possible.  Particularly if you enclosed the printer with enough insulation to get the air temp well over 40C.

 

If you feel more friction in the Y axis than the left axis then that is definitely the problem.  You need to start taking everything apart in the gantry and figure this out.

 

Actually first thing - check that the two smaller diameter rods going through the print head are perpendicular.  Sometimes a belt skips a tooth.

 

There are great videos and descriptions showing how to take the gantry apart.  Look around.  Don't try it without watching a video first as this will save you hours.

 

I helped one school fix their printer that had too much friction on one axis.  One of the rods had some kind of gunk on it - I think maybe hairspray.  I had to try many solvents before I got it clean and moving again.  I also had to take apart one sliding block and remove the rod and use a hammer and vice to unstick it.