How to add a pellet extruder to MK3s+
Hi, I'm trying to build a modified pellet extruder on the MK3s+ to be used with granulated sugar and would be grateful to anyone who can assist with a couple of unknowns. So far looks promising in terms of weight and fitting it all on but there seems to be three main issues.
The first two relate to the extruder hardware. For the geared extruder stepper motor I need to set the eSteps and figure out which wire from the motor plugs into where. The motor manufacturer has given me the wiring specs for B+ B- A- and A+ but I can't work out what the order is on the board ( https://reprap.org/wiki/EinsyRambo). So far I'm just trying combinations that I've used with other stepper drivers without success. For setting the eSteps, on firmware version 3.11, can we still just use a dummy print file with the lines:
M92 E830
M500
Not sure the values are being written and saved. Maybe it is best to put in some custom gcode at the start of each print? I also think I need to add some custom gcode at the start of each print anyway to be able to use it at low temperatures (I think about 140 degrees Celsius) , maybe something like disabling cold checking completly: M302 S0?
I've managed to make all the mounting plates and fan assemblies but so far can't get the extruder motor to turn. On my test rig I have the motor turning using a polulu driver connected to my PC at approximately 0.5 mA. So seems like the standard power available from the board should be enough to drive the motor.
I had to downgrade the firmware back to 3.11 so that the thermal model isn't included - this will trigger it for sure 😉
Any help would be greatly appreciated!