02. Calibrate your printer - FLSun3dp/FLSun-Kossel-Mini GitHub Wiki

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Written by: Maxim Riabichev

Before you can print with acceptable quality, there are a couple of things you need to calibrate first.

This link will take you to an online spread sheet which has three pages/sheets at the moment. Go there and open the "Steppers" page (look down for pages). It will help you with calculations.

1. Calibrating tower steppers, a.k.a. axis steppers

  1. Mark a fixed point on the frame for each of the three axes. You can use some paper tape for instance.
    Or you can use Steve Hennerley's method to measure carriage travel distance: Take your calipers, pull out the measure stick more than 100 mm and zero it. Put it under the respective carriage and keep it in place while the carriage pushes the caliper stick down (with the next step).
  2. Lower the effector 100mm (G91 and G1 Z-100) and mark the new position.
  3. Measure how much each carriage has moved down.
  4. Use the spread sheet, or manually calculate the proper steps/mm for each tower with this formula: original steps per unit (100) / measured length * 100.
    Example: 100/95*100 = 105.26
  5. Change the steps per unit with 'M92 X**.* Y**.* Z**.*' and save with M500.
    Example: M92 X100.3 Y100.3 Z100.0
  6. Voluntary: Save these calibrated values in firmware:
    Find the line #define DEFAULT_AXIS_STEPS_PER_UNIT { 100.0, 100.0, 100.0, 100.0 } and replace the first three values with your X, Y, Z values, in that order.

2. Calibrating the extruder, a.k.a. e-steps

  1. Disconnect the bowden tube (the white tube) from the effector. The filament is not supposed to go through the hot end during the calibration process.
  2. Heat up the hot end (via Repetier Host for example). If you don’t you won’t be able to extrude/retract the filament.
  3. Extrude a small amount out of the bowden tube and mark a spot on it, directly outside the tube for example.
  4. Via Repetier-Host for example extrude 100 mm and mark a new point (again, directly outside the tube for example).
  5. Measure the distance between your two marked points on the filament. This value will now be referred to as “measured length”. If the value is 100 mm then you are done. Jump down to next section.
  6. Use the spread sheet, or manually calculate your steppers step with the following formula: original steps per unit (100 or 150) / measured length * 100 Example: 150/95*100 = 157.8947
  7. Send the command 'M92 E'. Example: M92 E157.8947
  8. Save with M500.
  9. Voluntary: Save this calibrated value in firmware:
    Find the line #define DEFAULT_AXIS_STEPS_PER_UNIT { 100.0, 100.0, 100.0, 100.0 } and replace the last value with your new one.

3. Measure your filament thickness at 3 to 5 different locations and take an average of them

Average of 3 values = (value 1 + value 2 + value 3) / 3

Put this average value in your slicer of choice. It is a specific parameter in the slicer application called for example "Filament diameter".

4. (Optional) Perform a PID tune for the heated bed and hot end

This step is optional at this stage, the PID-values available in the sample configuration files are good enough.

Enable the PID-tuning of the heated bed by uncommenting (removing the //) the following line in configuration.h:
#define PIDTEMPBED

Follow the guide here: http://reprap.org/wiki/PID_Tuning
Send the following commands with the corresponding PID-values:
M301 Px.xx Ix.xx Dx.xx
M304 Px.xx Ix.xx Dx.xx

5. Run the G33 command

A word of advice: When calibrating the printer, always keep a finger on the reset button on the printer (or the emergency stop via software) and use it if your effector starts digging into the bed and/or hits the belts or performs other mechanically dangerous actions. This will prolong the life time of your printer (diagonal rods, belts, etc).

With that said, I suggest you run G33 with different P-parameters in the following order:

  1. G33 P1 - This only verifies and sets your Z-height.
  2. G33 P2 - This only probes the center and each tower.
  3. G33 P5 - This probes more points, for a slightly higher calibration precision.
  4. G33 P10 - This probes many more points for even higher calibration precision.

Why run them in this order?
The short answer is for printer health reason. Basically, if some value in configuration.h is wrong (for example Z-height being too large, or if your Z-probe doesn't work, and so on..) the calibration routine can create situations which could be mechanically dangerous for the printer. To minimize the potential damage, I suggest taking these "baby steps" first. But, certainly, once you've performed these steps in this order with positive outcome once, you can go straight to step 4 in the future. If you are brave.. ;)

What should I look for when the routine finishes successfully?
Your final standard deviation (st.d.) value should be <0.06. You will find this value in your software of choice.
If it's higher, you might need to look over the mechanical build of your printer once more.

6. Set your Z-offset

Guide here.

7. Send M500 to save calibration from RAM to EEPROM

RAM cleares on power loss. EEPROM lasts until next firmware flash.

That's it!

You can now continue to the next section: Configuring the slicer

I3

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