weird layer shift during printing

[taavet 0]

Hi All,

i am quite confused - during the print suddenly the layers "shifted". I try to link a pic because it explains what i mean.

Is it possible because i played with ultimaker controller speeding up the print? Originally the speed was about 75mm/s, but i cranked it up to 130%. The layers become somewhat loose as you see from the layers above - could it be i speeded it up too much? Then i slowed it all down back to 100% and then this "layershift" occurred. I did same print with white PLA plastic before and without any issues like this. Is it possible that PLA-s behave differently?

What might be the reason for giving that kind of result?

Thanks in advance!

taavi

 

[taavet 0]

oh, sorry - this thread should be under "art of printing"!

 

[gr5 2,167]

This "shift" is very common. One of your pulley's slipped. Either X or Y. I can't tell if your shift was in X or Y but you should be able to tell.

Tighten the hell out of all 6 setscrews on the 6 pulleys for the axis that slipped. Not just the 4 pulleys on the long belts but also the 2 pulleys on the short belt (the belt to the stepper motor).

Also consider marking the pulleys and rods with a marker to see if it shifts again you can tell which one shifted.

Also your UM should have come with 12 extra set screws that are silver colored. These screws are better than the black ones that came with the pulleys.

 

[gr5 2,167]

By the way - when you sped up the print near the top - you can see the quality of the wall got worse. This is called "underextrusion". The problem is the filament isn't getting through the nozzle fast enough. You can fix by either slowing down or instead you can simply raise the temperature. I often print as hot as 240C when I am printing something fast like this.

 

[irongland 1]

Hey I had problems like this before I lowered the amperage to my steppers (use a guide for this) and oiled my x y blocks with some 3 in 1 oil. Basically the motors were getting too hot for a second and shut down for a very short time causing the misplaced print head. Essentially it acted like a shifted belt, but my belts were great and the pulleys were tight. I had to witness this to figure out what happened.