GUS Simpson electronics and calibration

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GUS Simpson Documentation


GUS Simpson has no firmware yet. In order to get it working a gcode preprocessor is used, while GUS being configured as a dummy cartesian printer. Be aware that sending a cartesian gcode on the GUS may harm the device, and never would give any results. While you can use pretty much any firmware capable of running cartesian printer, a [Repetier] is suggested.

Configuring the firmware

Start by configuring the firmware. Most firmwares comes with default settings for X, Y and Z axis. You will need to configure the firmware so the X, Y and Z motors have the same settings. Do not configure steps/mm just yet, give it placeholder value, you will need to change it later. Here is an example [Repetier] configuration.

Calibrating steps/mm

It is very important you do this right. You will need a calipers capable of measuring at least 300mm.

  1. While having placeholder values for steps/mm, detach the arm you about to calibrate from the hub.
  2. Home all the axis.
  3. Make sure eccentrics are fixed solid.
  4. Home all the axis again.
  5. Measure bolt to bolt distance on the ends of the arm with the calipers and write it down.
  6. Close the arms as much as possible and write down software coordinates of the arms. Make sure there were no skipped steps.
  7. Measure bolt to bolt distance again, write down the value.
  8. Calculate new steps/mm value: A * S/(Max- Min), where A is the old steps/mm value, S is software coordinate and Max and Min are bolt to bolt distances.
  9. Place new values in the firmware.
  10. Repeat, until you have the same value after calculation.

Calibrating segmentize

When you have steps/mm figured out you should add some points to segmentize. Open the script in text editor and find the POINTS array. You should fill it with at least 6 points where the extruder barely touches the bed. You should be able to slide a piece of paper between the nozzle and the bed with no dragging. Once done the segmentize should be ready for printing.