Multi color printing with Prusa's MMU V2 & Duet?

fma

Great!

Does anyone understand how 'ramming' params work?

bartolomeus

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

fma

Yes, but what if the input is never triggered?

bartolomeus

@fma why would the sensor not be triggered?

fma

If case the filament does not engage correctly in the carriage, because of melted end (blob).

bartolomeus

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?

fma

Yes, sure! This is simple motors, so a couple of G1 commands should do the job. And the carriage needs to be homed.

bartolomeus

I don't see any homing switches so I guess it relies on sensorless homing

fma

Right. It uses TMC drivers...

Red Sand Robot

If it uses sensorless homing normally, wouldn't installing a normal endstop switch correct for that issue?

fma

Yes, sure. And it should be easy to do.

Oliman

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?

bartolomeus

@oliman I was going to. Awaiting a bit more reviews on the MMU2 and maybe the first design iterations.

Oliman

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.

fma

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.

bartolomeus

Someone is already designing an alternative. The design is on thingiverse. He also has a thread on this forum somewhere,

fma

In fact, there are 2 designs on Thingiverse (both guys are on this forum). I started mine because it is different in many ways...

OBELIKS

@fma Do you really think it would be easier without MMU v2 electronics? I think it should be possible to send the code to change the filament. But it is true you would need to change Duet FW to support this.
I really hope it will go this way.

fma

Well, wiring the motors on the Duet is a solution you can use right now, without any modification, so anyone can do it, and it does not need too much efforts nor skills...

I'm not sure it will be possible to communicate with the electronic, as it uses a SPI bus (MOSI/MISO/CLK are available - maybe not on a header, though - but it needs an additional CS - chip select - signal).

dc42

If the Prusa MMU needs 3 stepper motors, I wonder whether there is any cost saving compared to a 5-input Diamond, or a QuadFusion if 4 colours is enough for you; plus the 1 or 2 additional stepper motors and drivers. Also the Diamond and the Quad can do colour mixing, although the mixing isn't perfect.

If the MMU communicates with the main electronics via SPI, then you could connect it to the daughter board connector on the Duet. Of course, RRF would need to be modified to support the MMU.