This is a plugin for the 3D printer host software, OctoPrint (http://www.octoprint.org).
This plugin is designed to accurately calibrate the RAMBo and Mini-Rambo based line of delta printers manufactured by SeeMeCNC (http://www.seemecnc.com). This limitation is due to the code looking for special output that is generated by SeeMeCNC's accelerometer probe and its associated fork of Repetier Firmware. This plugin can be modified to include other models of delta printers if the probe information is supplied. A printer to test on would be nice too. :)
The "brains" behind this calibration plugin were graciously supplied by David Crocker (dc42). David's "least squares" calibration algorithm is so good that it's essentially magic. The calibration code in this plugin is the same code that can be found behind his website, here: http://www.escher3d.com/pages/wizards/wizarddelta.php. His calibration routines are also found in the dc42 fork of RepRapFirmware for the Duet controller.
Many thanks also to Ryan Rittenhouse, SeeMeCNC's new cat herder (software developer). If it wasn't for his valuable assistance, this plugin simply wouldn't have worked right for a very long time.
The core of this was shamelessly stripped from https://github.com/platsch/OctoPrint-Autocalibration. Pretty much the only thing left is the routines used to read/write the EEPROM. :)
To use this plugin, you can install it using pip from a shell prompt:
pip install https://github.com/geneb/OctoPrint-Delta-Calibration/archive/master.zip
If you're working with an OctoPi distribution, you can sign into the "pi" account and install the plugin this way:
/home/pi/oprint/bin/pip install https://github.com/geneb/OctoPrint-Delta-Calibration/archive/master.zip
You must also be running a version of Repetier Firmware from SeeMeCNC with a firmware date of 20161209 or later. (Issue an M115 to see the firmware date, ex.: FIRMWARE_NAME:Repetier_0.92.2 FIRMWARE_DATE:20161209 MACHINE_TYPE:Rostock MAX v3)
Before running this utility on your printer, you should issue a G29 command via the OctoPrint terminal. This will kick off the internal calibration and will get the Z height properly set.
In order to use the plugin, click on the Settings link in OctoPrint and then click on the "Delta Autocalibration" link that's listed in the Plugins pane on the lower left.
Click the Load EEPROM button and then click the Begin Delta Calibration button.
You may run it as many times as you like, but you MUST click the Load EEPROM button before you begin the calibration sequence! If you fail to do this, the calibration routine will NOT know what the current parameters are and you'll get poor, bad, or moderately catastrophic results.
[07Feb18] I've updated the plugin so that it checks 16 points (10 outer, 6 inner) instead of the usual 10. This appears to result in a better calibration, at least with the machines I've tested on.
Enjoy!