Consistent layer shift around holes

[DrCobras28 0]

I have an Ultimaker Original + and am attempting to print a pneumatic engine, but I am running into a problem with this strange micro layer shifts. These shifts consistently appear around holes and when the print transitions from a flat face to a more complex geometry. I have tried a a variety of trouble shooting tips including checking belt tension, ensuring the pulleys are tight, and changing heat and extrusion settings. None of these alterations have done anything to minimize this issue, as you can see in the picture of the three attempts. I have also checked the layer view in Cura, and these defects are not appearing on the model, which points to a potential hardware issue. I have also noticed that these printing artifacts do not appear on circular or rounded models, but only those with flat faces, and these issues occur equally on all sides of the print.

 

Any help on this topic would be much appreciated as it is currently the only thing standing between me and my completed project.

[gr5 2,172]

It's almost certainly "play" or backlash (read about it on wikipedia if you aren't familar).

 

It happens because it is for example coming at a wall from a different direction or switching from clockwise to counter clockwise.

 

Play is most commonly caused by loose belts - the short belt on the motor is the most important and easiest to tighten but the long belts are important too.  I know you think you tightened everything.

 

Play can also be caused by high friction.  If the friction is too high then when it is for example moving the head to the right and the steppers stop moving, the belt is stil trying to pull the head but friction is keeping it from moving.

 

Play can be caused by loose parts INSIDE the print head.  Try pushing on the nozzle in 4 directions

[gr5 2,172]

Sorry - had an emergency.  I'm back.  Anyway, if the belts are too tight you can get heavy friction.  More likely if the end caps that hold the 4 rods in the sides of the printer are too tight that can cause too much friction (hence backlash).  You should be able to push the head around with just one finger on each opposite block.

 

Watch this video to know the correct tension for the belts (precisely with a guitar tuner app on your phone) and also maybe get an idea of how easy it should be to push the head around: