3D Printer Problems and solutions

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Cura or Pronterface won't connect to the printer

Symptom: In Cura you only have the option to save gcode to file and not to print directly. OR . Pronterface hangs when you click connect.

Solution: Make sure that the printer shows up in Device manager under Ports (COM & LPT). If it doesn't show up, you need to download and install the teensy USB serial driver located on the \\steamserver under software/3d printing. If it shows up in device manager but still won't connect, disconnect and reconnect the printer's USB cable from the computer and immediately try to connect.

Nozzle is scraping into the bed

Symptom: The tape gets wrecked by the nozzle every time you start a print.

Z height needs to be calibrated.

Coarse calibration is done by adjusting the height of the bed probe. Heat up the nozzle and remove any pla that is on it and let it cool. Move the nozzle down until it is just touching the bed. Use 2 wrenches to loosen the nuts holding the bed probe in place. Use 4 business cards or pieces of card paper as a spacer and re-tighten the bed probe that height above the bed. Double check that the spacing is correct and the probe is tight.

Fine calibration is done in software. Open pronterface and type M501 in the command line. The last line of the readout will look like M212 X0.0 Y0.0 Z0.0. Copy and paste this into the command line and change the Z value so that it reads M212 X0.0 Y0.0 Z-2.0 and hit enter. Send M500 command to save the settings. With the nozzle hot, home the z axis (this will be Z0.0) and use a sheet of ordinary paper as a feeler gauge. Bring the nozzle down on top of the paper by 0.1mm at a time while counting the number of steps until the paper just begins to be difficult to move. Sometimes the nozzle is already too low, in this case bring the nozzle up in the same manner until the paper becomes free and then go back down one step. Keep track of how much you moved the nozzle and put this value into the M212 command ex: if you moved down by 0.1mm 3 steps, put in Z-0.3. If you went up 3 steps and then back down 1 enter Z0.2. Save the settings by sending M500. Make a test print to test the calibration. If the extrusion doesn't stick or wiggles as it comes out, the nozzle is still too high. If the extruder still wrecks the tape, or the extruder motor skips, or the nozzle plows through the first layer, the nozzle is still too low. A proper first layer extrusion sticks well but doesn't have plow marks. Plowing.jpg First layer.png

Extruder nozzle is clogged

Symptom: The hot end is up to proper temperature and the extruder motor tries to push the filament bot nothing comes out, even far above the build plate.

Possible solutions in order of simplicity:

  1. The filament hasn't threaded properly into the hot end and is hitting something. Guide the filament into the hole at the top of the hot end. It should go in about 5cm.
  2. Low quality filament. Some filaments from china have many impurities that melt (or don't) at higher temperatures. Get some real filament and don't cheap out!
  3. The nozzle is actually clogged
    1. Heat the nozzle up to over temperature (250deg) and extrude the blockage out.
    2. Warm pull the filament out the top of the extruder and discard the end to hopefully remove the blockage.
    3. Mechanically remove the blockage with a small wire or drill bit
    4. Replace the extruder nozzle

Holes are too small

Symptom: Holes in your print are too small.

Solution: (Tested on Printrbot Simple Metal. Clear PLA. Default slicing settings in Octoprint. 0.25 in nominal hole diameter.)

Make the holes about 0.015 in (tight fit) to 0.020 in (freely sliding fit) larger in diameter in your model.

Filament doesn't stick to bed

Symptom: Filament extrudes properly, but doesn't stick to the bed.

First, double-check that you're not trying to use ABS on a Printrbot Simple Metal (the top row of machines)! ABS requires a heated bed, which these machines do not have.

OK, so you've checked, and you're definitely using PLA. Now what? The nozzle could be set too high, so that the extruded PLA isn't close enough to the bed to stick. To fix this, go to OctoPrint > Console, turn off Autoscroll, and:

// check current settings M501 // this should print out a bunch of lines, including (near the bottom): Recv: echo:Bed probe offset (mm): Recv: echo: M212 X0.00 Y0.00 Z-0.20 // now set the bed probe offset lower, e.g.: M212 Z-0.70 // save the changed settings M500 // double-check that settings have been saved M501 // now you should see Recv: echo:Bed probe offset (mm): Recv: echo: M212 X0.00 Y0.00 Z-0.70

Be careful when setting M212: if you set it too low, the nozzle will dig into the bed. You can check a working printer using M501 to see what its bed probe offset is, try that on the non-working printer, and make small adjustments afterwards.