Kossel magnetic endstop z-probe (zero x/y & low z offset)

thingiverse

Based on paul_delta's zero x/y offset probe (http://www.thingiverse.com/thing:1198256), I had my very first real success calibrating my Delta printer using this online calculator: http://escher3d.com/pages/wizards/wizarddelta.php by the user dc42. Compared to paul_delta's design, this remix has some benefits: Lower z offset (paul_delta's design: ~ 120 mm, this design ~ 30 mm) Less mass -> less tendency to swing/vibrate due to high acceleration Low activation height (~ 0.5 mm) As with paul_delta's design you will need some rare-earth magnets, which are glued onto the z-probe and the effector (see photos). I used 10 mm diameter and 1 mm thick ones. If you want to use others - just adapt the .scad file. Also, if you have other Delta effector offset etc, see the .scad. Using this probe, David's calculator and Repetier's bed correction, I managed to lower the bed height deviation to +/- 50 µm max (25 µm standard dev.). Remarks: I had slightly better results (standard deviation from 31 µm down to 25 µm) when not neglecting the residual x/y offset (for me x = -1 mm, y = -1,3 mm). But your mileage may vary. To measure it I use following method: Position the nozzle ~ 0.2 mm above bed (x/y = 0), extrude 1 mm filament and move the nozzle up. There should a little blob be sticking on the bed surface now. Attach probe, move nail exactly above the extruded piece on the bed. Your offsets are the negated x/y values you can read off your display / host software. This probe will fit paul_delta's probe storage. I do recommend a probing speed of 2 mm/s - ish for most accurate results. This was my very first experience with OpenSCAD. I LOVE IT! V1 is the old design with a nail (see updates below). I would recommend to use V2. V2 has a non-rotating pin, which should be printed in ABS, see printing / post-printing. Update 17.02.2016: Added video of the endstop in action. There will be a V2 coming soon! I have the slightest deviation in z-height (~ 50 µm) when the nail is rotating in it's guide hole. I am trying to print out the probe point in ABS and make it non-rotating. Update 18.02.2016: V2 is online and works like a charm! Non-rotating pin makes all the difference! Update 22.02.2016: Added some details on how to calibrate your Delta printer using this probe and the mentioned calculators. Update 23.02.2016: I am adding the Custom Section below, where you can add your own thank-you notes. Custom Section Thank you Paul, for his ingenious design. :) http://www.thingiverse.com/paul_delta/about David, for his ingenious calculator. http://www.thingiverse.com/dc42/about Professional3D, for his .scad of the E3D hotend: http://www.thingiverse.com/thing:548237