Here's my first attempt at a tool change wiper. It's just a bar that hangs off the right side, covered in some kapton tape to make it easier to clean off. The tool change script retracts the old tool 6mm, switches to the new head, moves it just past the wiper, extrudes 6mm to get back to zero, and moves over the wiper at a moderate speed to wipe off any residue. It is adjusted to barely contact the nozzles as the pass over. Here is my tool change code:
Code: Select all
; tool change: [old_tool] -> [new_tool]
T[old_tool]
G92 E0
G1 E-6 F2400
G92 E0
T[new_tool]
G1 X225 F12000
G92 E0
G1 F2400 E6
G92 E0
G1 X215 F1200
My startup code also uses the bar to prime and wipe both nozzles. It does T1 first and leaves it in a retracted state, then does T0 and starts immediately:
Code: Select all
M201 X1000 Y1000
G28
T1
G1 Z5
G1 X225 F9600
G92 E0
G1 E25 F225
G92 E0
G1 E-6 F2400
G92 E0
G1 X215 F1200
T0
G1 X225 F9600
G92 E0
G1 E25 F225
G92 E0
G1 X215 F1200
Simplify3D does some really strange things with the tool change code, like changing from T0 to T0, then from T0 to T1, then T0 to T1 again. It seems broken. I had to go in and fix up the gcode in an editor. The comment at the top of the tool change script makes that easier, as you can just search for "->". You need to remove any instances of weird tool changes manually. Thankfully, they appear to all happen only near startup. Make sure you keep looking until it seems that all the tool changes are swapping back and forth between T0 and T1 regularly.
The wiper seems to reduce contamination somewhat, but part of that is just moving the nozzle away from the print while resetting. If you don't do that, it will reset the new tool head wherever it happens to be, then drag the ooze over your print getting to the next print position.
There is still contamination happening from the unused head drooling slightly while not printing. Maybe some more aggressive retraction will help with that.