Holey Triangular Calibration

Here are updated and consolidated instructions.

There is a fork on GitHub which is functioning. If you would like to use it, you will have to be willing to open a python script and modify text as part of the calibration process, and install the Python scipy package (which is pretty straight forward). Otherwise, it is very similar to going through the current triangular calibration. I would like to get one or more other individuals using it, to further demonstrate its viability and create some interest, to get it into the main distribution.

Calibration Process

  • Download and install GC and the Firmware from the above locations
  • Install numpy and scipy Link to Instructions
  • Install the Firmware on the Arduino.
  • The sled-weight is measured using a scale (lbs).
  • Run Ground Control from the new folder
  • Enter the sled-weight (lbs) into the “Advanced System Settings => Chain Sag Correction Value for Triangular Kinematics”
  • You should start with a reasonable calibration based on physical measurements. Your machine should know a reasonable home position before starting the calibration cut.
    • Measure the motor-to-motor distance by with a tape-measure. Enter the value into “Maslow Settings => Distance Between Motors”
    • Measure the distance between the top of the worksheet and the motor-centers. Enter the value into “Maslow Settings => Motor Offset Height MM”
    • Go through the “Actions => Set Chain Lengths - Automatic” exercise.
  • There is a file, SixHoleCalibrationCut.nc in the folder, GroundControlUpdate/gcodeForTesting which drills the holes for the calibration. Set it up on your machine and run it.
  • Measure the center-to-center distance between holes as is shown in the figure in this post
  • There is a file in the Ground Control download named RunHoleyCalibration.py .
    • Open it.
    • There is a section where the initial machine parameters are entered as text, from lines 6 to 13. Type your initial machine parameters in the appropriate locations.
    • There is a section where the measurements are entered as text starting at line 24. Units are in inches. Enter your measurements, top to bottom, where M1 is on top and M12 is on bottom.
    • Run the script.
  • It will print out a calibration result. It will report optimized values for: Distance Between Motors, Motor Y Offset, Left Chain Tolerance, Right Chain Tolerance.
  • Copy-paste the values from the report, into the appropriate GC settings.
  • Force the firmware to update
    • Disconnect and reconnect the arduino by unplugging the USB cable, and re-plugging it in

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