How do I calibrate the XY offset with Cura

If you want to set the XY offset very precisely, you need a different tool than Weedo offers. For our setting you need a vernier caliper or a micrometer. If possible, use two identical materials from the same manufacturer, but different colors, for the setting. First of all, the dimensional accuracy must be checked and adjusted. This is important so that you can use different materials and manufacturers together (materials have different shrinkage, etc.) Perform the dimensional calibration e.g. according to the instructions Teaching Tech 3D Printer Calibration. The correction factors are inserted in the Cura Configuration X40 PRO. You may not need to do this then. Then print the 2x2 checkerboard pattern without an offset (middle of the settings on the touch display). If the offset is greater than 2mm, then the tension on the belt is no longer correct. If necessary, adjust the belt or the offset.

 

Z-Offset Calibration

Some have trouble getting the Z-Offset on the Weedo X40 print head right, so here's my tip. If your print bed is not aligned, then perform a manual bed leveling beforehand. Start the printer and move both printheads to the center of the print bed. Use the arrow keys on the display to move the printheads about 0.5 to 1mm over the print bed. Use a sheet of paper and place it between the print bed and both nozzles. Loosen the screw from the right extruder to adjust the height. Carefully lower the print heads using the arrows on the display until the sheet is pinched at the left nozzle. Press the right nozzle against the sheet of paper while tightening the screw. Both nozzles should now be pinching the paper and aligned. If the right nozzle is longer than the left one, you must first lower the left nozzle using the screw. Finally, don't forget to start the Z offset via the display.

 

 

XY-Offset Calibration with 2x2 Checkerboard

In the x40 community cloud directory there is a subdirectory with the name XYZ_Calibration_Tool.

  • Download the files XYZ_calibration_2x2_part1.stl and XYZ_calibration_2x2_part2.stl.
  • Create the print model with Cura according to the instructions.
  • Print the model with two different colors and without an offset (Average dimension for the touch display, X=353). The left front rectangle should be printed with the left nozzle and the right front rectangle with the right nozzle so that it is easier to see whether the offset needs to be increased or decreased. It is recommended to use AddNorth E-PLA, as the material has very low shrinkage and can reproduce the edges very nicely. Before releasing the model from the platform, check the offset and note the orientation of the model to the axes. You can also write the orientation of the model with a pen.
  • Now measure the rectangle with a caliper. The rectangle should measure 30mm x 30mm. If it is smaller or larger, then you very likely have an offset. If there is a deviation of 1,5mm or more, the belt should be retightened. The X offset is limited to 353 +/-2 by the firmware. Larger or smaller values are not accepted.

If the dimension of the front row is smaller than that of the rear, then the dimension of the offset must be increased. If the dimension is larger, the offset must be reduced. In my example, the rectangle measures 31mm or 29mm in the X direction and 30mm in the Y direction. So we have an positv offset of 1mm in the X direction.

 

To correct the offset, I go to the XY-Offset menu on the printer and shorten the distance by 1mm. I switched from 5 (353) to 4 (352). Depending on the firmware version, the dimensions of the picture may be different. Weedo integrated corrections in the course of the software development. 

To be on the safe side, I'll print the model again to check the change. If the surface of the checkerboard pattern is not to form a continuous plane, then the nozzle must also be set in the Z direction. 

You can also transmit the offset via Pronterface or Octoprint with the M218 command. Enter e.g. M218 T1 X354.0 to set the offset to 354.0mm. Alternatively, a parameter backup can also be performed on the MicroSD card. Then simply open the config.sav file with a text editor and adapt the M218 accordingly. After saving, reinsert the MicroSD card into the printer and import it again using the parameter function.  

 

Ultra-fine tuning

With the Weedo X40 3D printer, the setting of the XY offset is limited to an accuracy of 0.1mm. Even if you know the exact value, you cannot write it into the EEPROM because the value is always rounded to one decimal place. This is particularly annoying if, like me, you have an offset of 0.05mm. No matter what you set, there is no improvement.

 

 

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