Large Shifts on my prints

Hey all,

I am getting some shifting on my prints, and its pretty large. I cant for the life of me figure out what to check next. I have tightened the belts, set screws, tried various prints and it always shows up. I moved the location of the filament from the side to the top, no change. Its not in the same place either, but its pretty close. I am still a bit of a rookie with this, and tech support hasnt been very helpful with this endeavor. I thought maybe my front door slamming, or the upstairs floor was causing it so i moved the printer downstairs on a rock solid granite top. Im just at a loss…getting pretty frustrated

Ah, the attachments didnt post.

When you push the carriages check and make sure it’s smooth over the range of the axis. If there is too much drag it can skip. Also, you can turn down the acceleration through the LCD and that can sometimes make a print finish that skipped before with the same gcode.

It doesn’t look like any binding is happening at all. I tried moving it all the way and it looks smooth. I’m thinking it’s only on wide prints because my benchys and other small items come out fine.

It doesn’t look like any binding is happening at all. I tried moving it all the way and it looks smooth. I’m thinking it’s only on wide prints because my benchys and other small items come out fine.

If it only happens on larger prints it could be that there is something around that is catching on or knocking your print bed as it is printing and that is causing the shift. I would check and make sure there isn’t anything that could be limiting movement by snagging on the printer. The three major reasons for layer shift on a print is the pulley or belt slipping, the end stop being triggered prematurely and resetting the home position for the printer, or something disrupting the actual printer movement.

From what little I could see of the print, it looks like it is happening the layer immediately after what looks like a zip tie mounting point. Sometimes you get upwards deflection on a part as it cools on a larger layer, and depending on position it can be up far enough that the nozzle hits it, causing a shift rather than just printing over it. Usually that can be elminated by further tightening the belt, ensuring your printer is in a temperature controlled environment without major swings (i.e. an enclosure, and watching the print about at that layer and making sure you manually press any protrusions down before impact occurs. Or redesigning the part to elminate that lift point.

If its on the Y axis direction specifically, it could just be belt tension. A belt that is plenty tight for normal bed travel may not be tight enough after you double the mass on the bed.

But in this case i’m guessing that was an impact based off how little it shifted. Usually a belt shift will go several teeth over if it goes.

So, I started a print last night in more or less a square. Its shifting along the X axis, with not movement on the Y. (I think I am saying this right. Its the axis that the printhead moves along, not the bed) I checked belt tension and it seems to be ok, but I couldn’t figure out how to tighten the setscrews. None of my allen keys fit it.

You need a 2 or 2.5mm Allen key I think for those.

If it hasn’t been mentioned, check the GT Belt fastening system to the X-Carriage and bed. They can become loose from the movement over time. Lock washers help to keep screws tight.

So my belt was a little loose and I tightened it. I had two really great prints, both smaller, and I ventured back into a larger one. It the worst I’ve seen yet. I caught the nozzle dragging across the print too.

If you are using PLA, you may need to add an additional cooling fan. I’ve had the nozzle drag issue (but not the shift issue) and it was resolved with addition cooling. PLA loves cooling.

I’m not opposed to adding another. I’ve already purchased a dual extruder (worthless and I gave up on it), replaced the stock nozzle and replaced the bed with the new modular one.

How would I add a second fan?

Here’s how I did it. I started with a manual solution and then added two 80mm fans attached to the frame and controlled with a DC Motor / Stepper hat on the Raspberry Pi running OctoPrint that controls the printer. The 80mm fan speed matches the speed of the cooling fans on the tool head (controlled by M106 and M107 gcode commands). The hat can control two more fans if I need them.