First Tests

When you are done with your configuration, you should connect the printer and upload the changes. With some luck you have no syntax errors. Now you need to validate your parameter and test if all functions are working.

Check connection

The first test is very simple. Connect the host of your choice with the printer. Send a M115 and check if you get an answer telling you the firmware type and features.

Validate moves

Send some move commands from your host. Start with short moves to validate your steps per mm. Test if you can move in all directions. If you can only move away from your end stops, your end stops are configured the wrong way around. Invert the signal setting in the firmware.

Take a ruler and try to measure if a 10cm move is 10cm long. If not adjust your steps per mm.

Validate end stops and adjust bed level

Now that you can move your extruder, make sure all end stops work. Be cautious with the z-end stop. The z axis has much force and can damage your bed. Move only in small increments when you are approaching the bed. At some point your extruder can‘t get lower, because the end stop is triggered. At this point you should have a minimal distance. A simple test is a sheet of paper. Put it below your extruder and test the force needed to move it. If you feel some friction and the sheet does not tear, the distance is perfect. Make sure you have the same distance at all points of your bed. Most beds are nor perfectly flat, so a deviation in friction to your paper is acceptable.

Validate temperature measurement

Most hosts read the temperature from the printer and show them somewhere. If not, send a M105 and check the result.  The returned temperature should be room temperature+/-2 degrees. Possible results:

  • Room temperature +/-2°C : Your thermistor is working.
  • Larger temperature deviation: You have selected the wrong thermistor type or temperature table.
  • >300°C: No thermistor connected. Possibly wrong pin assigned?
  • <0°C: Thermistor has a shortage.

Do this test for all connected thermistors.

Heater tests

Use your host to change the temperature of your extruder and heated bed. Watch the temperature. Most boards also have a led signaling power to the heater. If you have PID enabled for your extruder, you will see the led starting to flicker when it comes within +/10°C of the target temperature.

Extruder test and calibration

Put some filament of your choice into your extruder and start heating it up. Typical temperatures are 180°C for PLA and 240°C for ABS. Depending on the vendor and placement of the thermistor this may vary.

Make sure the extruder is some centimeter above your bed and start a slow extruder until you see filament extruding. Now take a marker and caliper and make a mark on the filament 14cm above the extruder. Measure the distance, the filament is sticking out of the extruder. Now extrude slowly 10cm and measure the distance again. The difference should be exactly 10cm, which is normally not the case for the first test. Now you compute the new setting for steps per mm of your extruder using the following formula:

newStepsPerMM = oldStepsPerMM*100/measuredDistanceInMM

Turn the extruder off, disconnect and upload the firmware again with the corrected value. Repeat the procedure until you are satisfied with the precision.

Information: Different filament types or filament pressure from the idler can change the result a bit.

Continue with “Z-Probing”

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