Lumps / bumps in my prints!

Hi there!

I got a used Lulzbot Taz6 from a friend and im having some issues with the print quality. I am very new to 3D printing so please go easy on me | (• ◡•)|

My prints come out just fine except for some glitches that are consistently in the same location on the print. The image I have attached is of one of the prints I’ve made where the lump-age is especially pronounced. I know the files are solid, so something is off with my printer. Does anyone know what could be wrong here? and if it can be fixed? Thanks in advance

Heres another with different filament. Should be a perfect donut circle, but it’s slightly off-kilter and has the surface bumps (That I sanded down slightly)

When slicing circular objects, a large number of very short gcode commands can be generated. These very short commands can easily overwhelm the (USB) serial connection causing the firmware to stall waiting for the next command which causes bumps and lumps in the print.

There are a few options to reduce the occurrence of this issue.

  1. Lower the Print Speed.
  2. Print from SD card instead of USB.
  3. Replace the very short gcode commands with arcs, i.e. G0-G1G2-G3.

This last option requires either native support in the slicer (which CuraLE does not have) or a gcode postprocessor like ArcWelder.

I have a TAZ 6 that I connect to a Raspberry Pi running OctoPi / OctoPrint. This frees my Windows desktop from the often long process of feeding gcode commands to my printer and eliminates the sneaker net transfer of gcode files via SD card. My TAZ 6 is also in a different room than my desktop system. OctoPrint provides a browser based interface to the printer and has a robust plugin library including ArcWelder.

Many slicers including CuraLE have the ability to interface with OctoPrint so I can slice an object, upload it to OctoPrint, the ArcWelder plugin will automatically process the uploaded file and can be configured to automatically start the print (I start prints manually from the browser). I can monitor printing progress from my desktop, tablet, or phone. With proper security precautions, you can even control your printer from anywhere on the web.

Check your belts and your pulleys.

When we see movements like this, it is usually do to the drive pulley that is attached to the motor being loose, or the belt being loose.

This will cause backlash to occur. With backlash, this will cause the tool head (or bed) to stay in position as the printer works out all of the slack in the axis and finally catches and starts moving again.

With where the patterns are on your printer, this would indicate you have some backlash in your x-axis somewhere. So check the set screws on the motor drive pulley and ensure that the belt is not loose.