Multi color printing with Prusa's MMU V2 & Duet?
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Yes, but how to manage it? There is not condition testing in G-Codes...
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A good point in this MMU v2 is the non Bowden configuration: the multiplexer is only used to load/unload filaments to the extruder.
I'm wondering if we could use it without the carriage selector, and use the passive splitter of the v1? This would need more tubes between the unit and the extruder, but it would be much faster to switch from one filament to another, and reduce the chance of jamming (at the input of the carriage)?
And the Duet integration would be much easier.
What do you think?
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@fma I think part of the multi color precision of the v2 comes from being direct drive versus bowden. So there's that.
I'm not sure you need conditional gcode and variables to make it work... couldn't it be scripted with macros as they are?
Even so, conditional gcode is being hinted at for the near future, so maybe it won't be long to wait.
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@phaedrux said in Multi color printing with Prusa's MMU V2 & Duet?:
@fma I think part of the multi color precision of the v2 comes from being direct drive versus bowden. So there's that.
My suggestion does not change that point: the MMU is still used to load/unload filament, extruder remaining on the printer carriage. But instead of having the moving selector, and only 1 PTFE tube, there is n PTFE tubes, and a splitter n-to-1 above the extruder.
Even so, conditional gcode is being hinted at for the near future, so maybe it won't be long to wait.
That's good news!
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Firmware for the MMU board has been published, as also the schematics of the board.
Looking at the slic3r profiles, there is a 'ramming' function. Apparantly this is to retract filament with a clean cone and no strings to avoid jamming.
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Great!
Does anyone understand how 'ramming' params work?
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Regarding conditionals, couldn't something like this be used with the filament sensor of the MMU: https://reprap.org/wiki/G-code#M226:_Wait_for_pin_state
or: https://reprap.org/wiki/G-code#M577:_Wait_until_endstop_is_triggered
or: https://reprap.org/wiki/G-code#M583:_Wait_for_pin -
Yes, but what if the input is never triggered?
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@fma why would the sensor not be triggered?
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If case the filament does not engage correctly in the carriage, because of melted end (blob).
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I guess that's why 'ramming' needs to be tuned properly.
Anyway, with those available gcodes should it not be possible to write some custom macro's?
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Yes, sure! This is simple motors, so a couple of G1 commands should do the job. And the carriage needs to be homed.
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I don't see any homing switches so I guess it relies on sensorless homing
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Right. It uses TMC drivers...
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If it uses sensorless homing normally, wouldn't installing a normal endstop switch correct for that issue?
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Yes, sure. And it should be easy to do.
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I was hoping to pick up the MMU2 to put on a custom printer with a Duet 2 board.
Is this something anyone has already accomplished or would it be supported by Duet at any point in time?Or is this only a home grown venture?
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@oliman I was going to. Awaiting a bit more reviews on the MMU2 and maybe the first design iterations.
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Thanks @bartolomeus, I'll keep an eye out on reviews but I think I'm convinced the MMU 2 will be better than the Palette+. At least the design principles of the MMU 2 seem more dependable (also I'm not a fan of the custom Palette+ splicer).
Anyways, maybe someone will come out with a more mod friendly or printer independent MMU 2 clone. I would rather support Prusa, but not at the expense of taking a gamble of the MMU 2 not working with a non-Prusa printer.
I'm sure someone smarter than me will figure it out soon.
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For sure, MMU2 seems more reliable, and easier/cheaper to fix if it brakes. And interfacing it with the Duet/Duex is easy if you remove the electronic, and wire motors to the Duet. Then it is just a matter of a few G-Codes as macros to use it. Maybe ask Prusa if they can sell it without the electronic?
BTW, I'm working on my own filament multiplexer, but a mix between v1 and v2: a passive mux above the extruder, like in the v1, but a simple loader, not Bowden, like in v2. I'm waiting for mini-clutch to test my design.
Frédéric
