MMU3 proposed changes sound great  

RE: MMU3 proposed changes sound great

Doesn't the control board have a power issue though?  There's a thread on here about it somewhere.  like a design flaw where in some cases one of the components drops below 5v. 

RE: MMU3 proposed changes sound great

I had kind of hoped they'd at least sort out the wiring mess. It wouldn't have been too hard to put a dedicated expansion port on the new electronics box, or use USB-C. 

RE: MMU3 proposed changes sound great

I'm wondering about how much they change the chimney. This is only one that caused lot of issue from what I have experienced. 

RE: MMU3 proposed changes sound great

Yaaa, there is no way that I'm using any part from my MMU2s in an upgrade.  The thing is POSESSED and I'm not risking screwing up a new one.  I am taking my MMU2s out to a field and going full gangster "Office Space" printer on it.

I know how these things are supposed to work, so I'll get a new kit for my Mk4 and give it a try.  But after tweaking it doesn't work, back it goes.  I'm not in for another years long dysfunctional relationship.

RE: MMU3 proposed changes sound great

I would have to agree with my mile high neighbor,  I'm not comfortable using any part of the mmu2s electronics in an upgrade.   That may have made my mind up for me as to whether to keep one of my MK3S+ printers as mmu-enabled....    I'm pretty sure mine is one of the units with the faulty power design, it happens once in a blue moon and is super annoying.   I think my mmu-enabled printer is probably going to go back to a standard printer when I upgrade to mk4

RE:

Why are they even offering upgrades when they KNOW there are x % units with randomly faulty electronics in the field? This will just create more frustration. Already the MMU1->MMU2 upgrade felt like a joke. Print your own parts and it was basically a complete rebuild with only a handful of old parts.

I treat mine like a monument of failure, if I had any knocked out teeth or photos of exes I'd put them in the same shoebox 🤪 I hope they at least print the MMU3 parts on MMU3-equipped printers this time, but probably not.

RE: MMU3 proposed changes sound great

It is going to be my high temp printer.  I'm going from Mk3S to Mk3.9, and I think I'll print all the parts in fiber PC and then put it in an enclosure to print higher temp materials.

Posted by: @ssill2

I would have to agree with my mile high neighbor,  I'm not comfortable using any part of the mmu2s electronics in an upgrade.   That may have made my mind up for me as to whether to keep one of my MK3S+ printers as mmu-enabled....    I'm pretty sure mine is one of the units with the faulty power design, it happens once in a blue moon and is super annoying.   I think my mmu-enabled printer is probably going to go back to a standard printer when I upgrade to mk4

RE: MMU3 proposed changes sound great

I don't really understand the reasoning behind keeping the MMU2 control board, 1.8 degree steppers and F.I.N.D.A. probe?

If Prusa is switching its printers to 32 bit STM controllers and 0.9 degree steppers, why not streamline the supply chain and base the MMU3 control board on the 32 bit STM chip, 0.9 degree steppers, and the IR filament sensor from the MK3S+ / MK4, skipping the LEDs and the two shift register chips on the control board?

If backwards compatibility was a corncern, the firmware for the existing MMU2S would have been updated and improved much more frequently.

RE: MMU3 proposed changes sound great

Perhaps because there is no real advantage and they have a lot of old stock that could do with using up rather than going to landfill?

RE: MMU3 proposed changes sound great

Probably yes, my MMU as yours was not so much POSSESSED, it had just several firmware with bugs, and the bloody set of communication cables that sometime become too tight and cause false power contacts (but I fixed several time dismounting all and then repositioned the cables with less tension when  it happened), but the real culprit is the firmware. They were never able to write a reliable firmware.  Sorry Prusa but the idea of not having any LED display but only buttons and LEDs was a failure. And even the communication protocol  between MMU2 and MK3 it's watering everywhere, and basically the MMU2 firmware often just do not speak any more with the MK3 and you have to reset the board through the pin button in order to take the control. 😠 

So my question is : will the MMU3 firmware be good ? 🙄 

Posted by: @cynan

Perhaps because there is no real advantage and they have a lot of old stock that could do with using up rather than going to landfill?

RE: MMU3 proposed changes sound great

@Terje

The old firmware was hacked together very fast.

Some people modified it and got rid of some bugs.

But the codebase was/is just so crappy that it isn't worth spending any time on it.

So a complete rewrite was the only viable soulution.

0.9 steppers make no sense on the mmu because they only feed the filament. The stepper on the toolhead does the main job...

RE: MMU3 proposed changes sound great

I'd like to see a new filament detection system for the hotend. The top hat is a pain to work with and around, and prone to detection errors, especially when it gets warm. The lever also makes servicing the hot-end a bit more problematic, as you now have to remove the door to get at the gears.
Not likely to happen, though, with the Mk4 having an entirely redesigned feed system.

I'd also like to see the thing be a little more tolerant to blobs on the end of the filament. Maybe have an option to trim the last centimeter off the end of the filament with every filament change, since there is already a knife incorporated. This will probably dull the knife pretty fast, of course, so there may need to be a way to easily swap out the blade when it's become too dull. Also, if it could somehow cut it at a bias, like we're told to do when feeding filament in in the first place.

I'd also like to see an option for a better drive system. The single-side pushed against a roller skate bearing is good enough...most of the time. When it's not, it grinds a divot into the filament and won't move it any more. This can happen if the spool gets stuck, (drying Prusament PETG in a dehydrator tends to sinter the filament, adding drag), or if the hotend fails to extract before cooling down, causing the filament to stick in the hotend before retraction is attempted.
If the motor could be polled for resistance, the way the printer is, so it could detect if drag in the system was over tolerances, and throw an error, that would help. Maybe it could even feed filament until it met resistance that way, and synchronize with the extruder. That AND a two-gear, or rather, a six to ten gear, (five top, one bottom, or five top and bottom, if the extruder gear couldn't be relocated to the shuttle), might prevent any more ground-out filaments.

As for the buffer. I'll not use it any longer. I'm (finally finishing up) printing up a better replacement, that uses a separate, removable, cartridge for each filament. The existing one would be TOLERABLE if it could be hinged open, like the pages of a book, or if you could unstack it to expose the one you're working with, so you could get at the filament easier. A hinge pair between every two of the plastic dividers. Or five modules, each composed of one plastic panel, probably the bottom panel for that filament, the two pneumatic push fittings, and a groove system to stack neatly, held together by a pair of spring clips, like the plastic latches of a Sterilite® box.

I've been down and gun shy for a few...months now. Chasing a fault, and finally just didn't continue..until day before yesterday. Turns out, there was a loose screw in my RAMBO enclosure, and it was probably what was preventing my bed thermistor from registering, (and maybe even why I thought it was the hotend thermistor long enough to order a replacement for THAT).

RE: MMU3 proposed changes sound great

Whoops. The current buffer design does NOT use pneumatic push fittings. It uses Bowden tubes, held in place with screws. There's just one such fitting on the whole system, and that's on the extruder. The one I'm replacing it with uses pneumatic push fittings. I think everything else is correct, though.

RE: MMU3 proposed changes sound great

What keeps them, outside of cost, from using 5 different motors- one drive motor per filament?

I’m hoping the new filament drive system in the MK4 helps to overcome bad tips…

RE: MMU3 proposed changes sound great

Hello,

The proposed changes for MMU3 sound fantastic! I had asked about the compatibility of the existing MMU2S Control board with the upgrade, and I'm pleased to hear that the new electronics rework will address the issue. It's reassuring to know that while the control board remains the same, there's an additional board in place to prevent the miscommunication problem that used to cause power issues with the cables. I've personally encountered this frustration with my MMU2S multiple times and even uninstalled it as a result.

I hope this will help you.

RE: MMU3 proposed changes sound great

Prusa tried it and it didn't work very well. .  It was called the MMU1. 

Multi Material Handbook

Posted by: @milehigh3der

What keeps them, outside of cost, from using 5 different motors- one drive motor per filament?

I’m hoping the new filament drive system in the MK4 helps to overcome bad tips…

skipped layers monster

Me being another one who put much love and time into the MMU2, before making the new investment, would humbly like to know how are they gonna fix the dammned skipped layers problem, MK3s extruder could not. I guess MK4 does, at least its price says it does miracles.

Anyway, problem being that the MMU2 doesn´t know for sure if the extruder is dragging or not the fil, how are they going to fix it?

RE: MMU3 proposed changes sound great

My mmu3 is giving me amazing results 

RE: MMU3 proposed changes sound great

Updated: Finally got time to mess with my MMU3. I would say that my MMU3 is working as what it supposed to do. It's much better than MMU2 (which I never got it to work at all!)