Bill responded directly to one of my questions about extruder loading problems and noted that using the 3Dchameleon mk2 as the extruder is quite the headache. As such, I wasn't going to go down that path but I did have a thought for your situation. If you were to want to reverse the direction of specific extruder I wonder if setting the steps/mm to a negative number in the extruder start/stop gcode would work in that instance? Not sure... and I'm sure it's not recommended. Maybe something like M92 E-93.0; set to -93.0 steps per mm (extruder moves in the reverse sense????) Then go back the other way with: M92 E93.0; set to +93.0 steps per mm (moves in the normal sense?) I've not tried it myself so I don't know if negative numbers are accepted, nor do I know how well it would work (guess this is a bit of a thought experiment and not backed by actual data). I think the bearings used in the 3Dchameleon to pinch the filament may hold with different strength and slipping might be more of a factor when trying to control filament flow with high precision?

Did a little more troubleshooting tonight and it looks like the issue is that things are getting caught on the edge of the boden tube on the exit side of the metal dual gear extruder I'm using. If I remove the tube, it seems to have no problems pushing filament through the hole on the output side though this probably makes any alignment issues less critical (but also far less useful). I'm wondering if perhaps my metal extruder is just not up to the task of allowing filament to be loaded cleanly without catching. In normal service, it would always have filament loaded beyond the exit point. I'll keep trying to work on flaring the end of the boden tubing to help the loading process. Not sure the capricorn tubing I have is helping me much in this service as it is very stiff relative to other tubing I've seen and clearances may be tighter down the tube. The extruder seems to have plenty of power once it grabs the filament and it's hard to make it skip manually once the filament is past the output of the extruder. I'll try to doublecheck the load speed. When the downstream extruder skips steps it does so continuously even after the chameleon has released the filament to allow the extruder to continue to feed it down the line so I think the problem is in my extruder at that point and not differential speeds? Does anyone have an extruder recommendation that might result in more reliable initial feed through?

Cool trick! I'll give it a go! So... if I understand this correctly... my firmware is currently set up such that max X and max Y are 220 mm. I can't use the panel controls to manually move beyond there although the actual clearances allow the print bed and/or printer head to move beyond those areas. BLTouch measures at those extremes (0 55 110 165 and 220) along both X and Y axis. Lets say I place my switch where it would presumably trigger at Y 223.0 (had I been able to move there without changing the steps/mm). Sounds like I'd move to Y 217.0 then double the steps/mm, move to Y 220.0 (via relative Y+3, which would really be 223.0 since we're doubled) then back to Y 217.0 (via relative Y-3, with steps still doubled). Then change back to original steps/mm? I'd imagine the gcode something like the following block: G90; move to absolute mode M82; turn absolute distance for the extruder G0 X55.0 Y217.0 F5000; <--- 6mm shy of button location at Y=223mm, X picked to avoid bed clip M92 Y160; temporarily double the steps/mm setting (to reach outside normal allowed Y range) G91; move to relative mode G0 X0 Y3 F2000; press the button (actually moves Y by +6mm since steps/mm doubled) G4 P1300; dwell for 1.3 seconds (filament select) G0 X0 Y-3; back off button (actually moves Y by -6mm since steps/mm still doubled) ; repeat above as needed for additional button presses... ; note: make sure we return to the original location prior to the button presses before ; restoring steps/mm setting. M92 Y80; restore original steps/mm setting (we're now back at X55.0 Y217.0) ...and so forth? P.S. I also like that your solution doesn't eat into my normal print bed range!😎

Here's one I tried putting together for the Ender 3 V2 Y-axis. Adapted from Bill's tinkercad switch mount collection. Screws into the lower left-hand slot of the Y-axis extrusion. Hole for the bolt and T-nut are offset as is the slot guide to allow the switch to be mounted closer to the end of the Y-axis rail. The offset also allows the bolt and T-nut to be accessed even with the switch board mounted in place and is low enough to allow clearance for the wheels. https://www.tinkercad.com/embed/983O52kxdbx?editbtn=1 I've printed and installed one. Seems to work though I've yet to try it out operationally. This one should be able to be placed beyond the 220.0 mm y-axis spot that interferes with the bed leveler. I've not yet been able to test it outside of the normal 0-220 mm range using the marlin controls on my ender 3 v2. Have yet to try using gcode to drive it into the switch. Hopefully the firmware allows this and doesn't clip the bed motion. I'm not very experienced yet with this stuff. Probably not the best model geometry after my hacking away at things but at least I'm having fun while learning! Glen