FolgerTech Kossel hotbed adjustable mount. Easy to calibrate.

thingiverse

I'm tired of tweaking my Folger Tech 2020 Kossel using z-probe, tested both - Marlin and Repetier. They calibrated properly, but I wasn't satisfied with the final results. The stock Z-probe is too far from the tip (X-Y offset) and even slight effector tilt yields very inaccurate values. So, I decided to make my own adjustable hotbed mount using spare screws from printer kit (3 M3x25, 3 M3x15, 3 Nylock M3 nuts, 3 washers and 3 M3 t-nuts for 2020 extruded profile), simple Sketchup-made mount (printed with PETG) and 3 springs I found in a $4 Homedepot spring kit. What a difference! It only took 15 minutes to calibrate the installed bed with high precision. Tip: Use small drill bit (1.5mm-3mm diameter) instead of paper for initial calibration - it gives some room between nozzle and bed and prevents head crash. Measure its opposite end (let's say it's 1.98mm), set Z height to 1.98mm, move the head as close to X calibration screw as possible and adjust so drill bit rolls slightly touching the tip. Repeat for Y and Z. Repeat the procedure if needed, then start adjusting delta radius. Repeat with paper test to fine-tune, if needed. Finally, I dismounted the probe (replaced with replacement mount that adds extra fan http://www.thingiverse.com/thing:1123295) and won't use it again... hardware calibration rules apply. PS: To avoid mess with slicer and make smooth transition during printing from hex-nut hole to M3, I designed a thin wall, so short bridges over hex-nut hole do the job pretty well. You need just puncture this thin wall using small screwdriver before inserting M3x25 screw.