Auto Retract Probe - Non-Servo

thingiverse

While thrilled with my FolgerTech printer and continuously upgrading over the years, I delved into a significant Marlin upgrade to incorporate Filament Runout Sensor. The bonus that came with it was Mesh Bed Leveling. Now ready for Auto Bed Leveling. Never having a probe and concerned about firmware file size using BL Touch, my latest project was inspired by the "Auto Retracting Z Probe" by NopHead and "ONZProbe" by Marco67. Combining the best features, I created a probe that works perfectly for me. While a very simple and efficient design, learning to save my prior flashed code from eeprom, setting up Marlin, working out the dimensions to match my machine, constant tweaking, modifying startup gcode so it would probe before every print; all required some long nights for me and printer downtime. As if the probe wasn't enough, I also incorporated a new fan shroud to my mounting bracket, moving the fan to the rear of extruder (both out of sight and for better balance on Y carriage) as the previous fan was bulky and I couldn’t see the nozzle or print under the shroud. All parts and dimensions fit the Folger Tech 2020 printer. While I have included a STEP file, adapting to this to other printers requires the bottom of mounting surface to nozzle tip height of 40mm or changes to probe length will be needed. All that’s required is a low-cost optical sensor, a 9mm dia x 10 Neodymium magnet, ¼” washer, some 6D bright finish nails, and a 50mm radial fan. The probe initially sits 5mm below the nozzle when probing. The probe breaks the optical sensor's light triggering precise bed height. Setting the Probe offset (in my situation to -5.25) brings the nozzle to proper print height when print starts. This is adjusted through your LCD display and doesn’t require Marlin. As it lowers to print, just prior to reaching print height, the magnet is attracted to the washer and retracts the probe up above the nozzle automatically and out of the way of print. After a few prints manually resetting the probe each time, I then modified my carriage end with an arm including an angled end. By adjusting my park position (set in Config Printer in Repetier-Host) I changed the x position to -5 (or 10mm travel farther left) which in turn pushes the probe down to its ready position. While making all these changes, I also modified my carriage end to include a belt tension adjustment. Probe Sensor End should ultimately be black and non-transparent. A deep Red might function well and double as indicator to remind you to reset. The runout sensor housing in these images houses a sensor from a Stratasys 370 printer bay I scavenged. There are plenty of simple limit switch designs on Thingiverse which can be used instead. The Runout Sensor is an awesome feature which I highly recommend! ALL AUTOMATIC EVERY PRINT. NO MORE BED LEVELING OR Z AXIS ADJUSTMENTS AND best of all, NO $40 PROBES! I ran an M48 repeatability test with these results. Mean: 4.902201 Min: 4.901 Max: 4.904 Range 0.004 Std Dev 0.001239 EVERY PRINTER IS CONFIGURED DIFFERENT AND I AM NOT GOING TO TROUBLESHOOT EVERYBODY’S SETUP NOR AM I RESPONSIBLE for changes you make to your printer! PROCEED AT YOUR OWN RISK! Not being insensitive, but I have enough trouble and time spent debugging my own problems. You should be very familiar with Marlin 1.1.9, gcodes, and mechanically witty. I am providing my Marlin configuration H file as reference only and it is not intended to be used as my pins and endstop settings, not to mention other settings could cause your machine to crash. I am providing these files mostly as inspiration for others. UPDATE 3/11/20: After using and enjoying this for awhile, I ended up printing a large project that started at the left edge of the bed. The probe overhung the edge of the glass and never tripped, snapping the probe tip (servo versions get out of the way obviously). I created the bed extension which works just fine and solved the problem. While at it, I created 2 shorter versions to act as a draft guard between the aluminum plate and Hot Bed. I don't suggest fully closing the area off and allowing too much heat to buildup, so only do 3 sides. The bed extension and draft guards still allow for bed level adjustment. I don't know if the draft guards improve bed temperature evenness or help in any way.