MMU 2.0 upgrade kit details technical differences
I have been closely following public pictures and videos of the MMU 2.0 system because I've had an order in since October 2017 for the new version.
Anyway, I bought the upgrade kit from the previous MMU but because that version works and is installed on a different printer, I'm not going to dismantle it to rob parts for the 2.0 kit. I mean just understand, back when I ordered, the upgrade was adding the new filament sensors, a couple of new changes to improve on the existing design. That changed to a complete redesign and massively different system that required a direct drive extruder (AKA MK2.5 or 3.0 printer with the direct drive Bondtech setup). Please, don't take anything I'm saying as a complaint (well, other than waiting forever for this to get to the point of shipping) as I'm getting a MMU 2.0 "upgrade" at a discount given the situation.
So that said, I want to know what parts are borrowed/used from the previous MMU now "required" to complete the MMU 2.0 upgrade?
Or said a different way, what is the parts difference from an upgrade kit MMU 1.0 to 2.0 VS full blown kit?
The sales page only says this: REQUIRED HARDWARE Original Prusa i3 MK2.5 or MK3 and Multi Material upgrade for MK2
So here is what I know from pictures. The MMU 2.0 uses 3 motors. 1 is a leadscrew motor, basically a shorter version of a Z axis motor. The 2 other motors are used for the long drive that drives the 5 extruder gears, and the other motor drives the "revolver" selector with the idler bearings.
Then an all new custom MMU2.0 driver board is used that is completely different and has onboard stepper drivers compared to the previous super switch board that just switched the extruder driver output to a given motor. The MMU2.0 no longer uses the Bondtech gears, it has completely different hardware and shafts, different bearings, different electronics.
So, based on my estimations and study, I think the MMU 2.0 "upgrade" from MMU 1.0 is borrowing 1 or 2 of the stepper motors (same as the extruder motor and so labeled). I think the MMU 2.0 upgrade kit would have to include the leadscrew motor since that is a custom unit specific to the MMU2.0.
But, there is a detail I was able to pick out between what was demonstrated at MRRF VS the unit demonstrated more recently at ERRF. This key difference is that the motor actually driving the feeder shaft is shown as a custom long shaft stepper motor with an extra long 5mm shaft in the video taken at BAMF (Bay Area Maker Faire), where the system shown at MRRF (Midwest RepRap Festival) has a 5mm shaft coupler, meaning it's just a normal (AKA reused extruder stepper).
Again, long shaft motor as seen at BAMF
VS
Short shaft motor (required from MMU1.0) and shaft coupler
Other thoughts of components that might be required or reused from an MMU.10
Pushfit connectors
PTFE bowden tubing
Bondtech extruder tension springs (actually compression springs)
Filament spool holders/rollers?
What I'm trying to get at here is the price difference between the "upgrade" and the full blown kit is $50 in price. I'm not complaining about the price, I'm just trying to ensure I know what parts are going to be reused from MMU1.0 as the truth is, there is such a difference in the system, and for me, my 1.0 has never yet jammed and has produced good mult-color (didn't yet get into multi material) such that I'm not going to tear down that printer and remove it. I specifically went and bought a brand new MK3 kit since this requires a Mk2.5 or Mk3 printer anyway.
Again, based on what I can determine and make assumptions on, the parts I think reused are:
1 or maybe 2 of the extruder stepper motors from the previous MMU kit. This is the debate of the long custom shaft motor being included and a potential difference between an upgrade kit and a full kit.
Obviously, one of the extruder motors is used for the "revolver" selector idler shaft and to me- that won't be included in the "upgrade" cheaper MMU2.0
Re: MMU 2.0 upgrade kit details technical differences
I guess put another way, a few of us may be in a "unique" group of owners. I don't know how many folks bought and actually have an MMU1.0. To further muddy that water, there were options such as how many filaments your MMU 1.0 kit was, I specially bought the more expensive quad kit. That kit came with 3 motors and you reused the existing extruder motor from your printer to make it 4 motors. Again, that kit was designed around the Prusa MK2 printer. So the upgrade kit at the time for the MMU1.0 improvement was simply 4 filament detectors (from the Mk3) and new 3D printed parts and maybe screws. Those folks who bought that upgrade got grandfathered in and are getting a MMU2.0 upgrade kit. As such, we are getting a steep discount for buying the previous MMU and since it was a preorder situation, having Prusa Research hold our deposit for going on 2+7=9 months, again, not complaining one bit.
But, again, I'm concerned about the difference and what is reused/required.
To me a long motor shaft is a superior option in this MMU2.0 design VS a short shaft normal motor and coupler. That said, that could explain the $50 price difference, but not really. The fact is, an extruder motor is $34. The full kit is coming with everything, so that means 3 motors. That means 2 extruder motors and 1 leadscrew motor. The question is, is that a custom long shaft motor or 2 short shaft motors? Depending on the answer in that question, then drives the next question, what does the upgrade kit give you given the $50 difference in price? In other words, if the upgrade kit requires 2 of your existing motors, and those are valued at $34 each, just call it $70 VS a $50 price reduction and maybe the difference between a custom long shaft motor VS a reused short shaft and coupler - and that could lead to shaft runout and all kinds of issues right?
Also take into account here, a MMU1.0 user that didn't buy the quad, I think they got only one extra extruder motor and then the one from the original MK2 printer. A person like myself got 3 motors and the one from the printer.
Or looking at it differently, I might still be able to use my MMU1.0 as a 2 or 3 input system depending on if I have to give up 1-2 motors to transplant into the MMU2.0 upgrade kit.
Re: MMU 2.0 upgrade kit details technical differences
Your analysis sounds correct to me, the only other thing I can think of is the MMU2 full kit probably includes 5 of the newer injection molded spool holders, while the upgrade kit probably comes with 1 spool holder at most (maybe none, or maybe 5 new ones, nobody knows yet).
Keep in mind the cost of the materials usually has only a small influence on the retail price, except for when you have lots of competitors all making the same generic product. I don't think there is any cause for concern of upgrade purchasers somehow getting a lesser product just because the price difference is larger than the difference in material cost.
Re: MMU 2.0 upgrade kit details technical differences
Somehow I've missed the video or pictures showing the MMU 2.0 spool holders. I've seen a few comments, can you link where you saw them?
Re: MMU 2.0 upgrade kit details technical differences
I'm referring to these, which started shipping with the MMUv1 late last year I think:
https://manual.prusa3d.com/Guide/5A.+Spool+holder+assembly+%28newer+version%29/502?lang=en
As opposed to the original ones:
https://manual.prusa3d.com/Guide/5B.+Spool+holder+assembly+%28older+version%29/365?lang=en
Re: MMU 2.0 upgrade kit details technical differences
I forgot about the 2 material MMU1. That would indicate that only one of the motors is reused as those with the 2 color don't have two to spare. So what I am guessing is that only one motor is reused, and yes perhaps the trays, but other than that everything else is new. For me it is a $150 difference between the upgrade and the full kit currently. I too have a fully functioning MK2S MMU1 4 color and was confused by the upgrade parts. Looking through the new kit manual they do include a long shaft smooth rod stepper(Pulley) as well as a tscrew stepper(Selector), and an extruder stepper. I think I would prefer to mount a spool rod on the wall myself after seeing that it needs to be further behind and the trays were always a bit fiddly(injection molded ones).
Anyone know when the upgrade MMU1 -->MMU2 kits are slated for shipping?
Re: MMU 2.0 upgrade kit details technical differences
I expect that the MMUv1 to MMUv2 upgrade kit will not contain the idler motor and pulley motor with the ~110mm long shaft because:
- The pulley body has a 22mm gap where a 20mm coupler (20 long x 12 OD with 5 ID) fits.
- Prusa have to make a difference between both kits, as the MMUv1 to MMU2v2 upgrade kit is €/$50 cheaper (normal price) than the complete MMU2 kit.
MMUv1 (2 and 4 changer) owners will be able to upgrade their MMUv1 kit reusing 2 Nema motors, which makes the €/$50 discount reasonable. Only additional things MMUv1 owners need is a ~90mm d-shaft + the coupler for the Pulley motor assembly.
Still wonder how the MMU2 control board will be connected to the MK25 miniRAMbo as the actual signal cable will connects it directly to the miniRAMbo reset line and not as on the Einsy to a controlled pin.
BOM difference between the MMUv1 to MMUv2 upgrade kit compared to the MMUv2 full kit:
-1x Idler motor
-1x Pulley motor
+1x ~90mm d-shaft
+1x coupler
maybe -4x spool holders
But we will see what will be shipped.
Re: MMU 2.0 upgrade kit details technical differences
Anyone know when the upgrade MMU1 -->MMU2 kits are slated for shipping?
One or two days ago I noticed the eshop product description changed from "late August" to "late September" upgraded MMU.
Neal
Re: MMU 2.0 upgrade kit details technical differences
I expect that the MMUv1 to MMUv2 upgrade kit will not contain the idler motor and pulley motor with the ~110mm long shaft because:
- The pulley body has a 22mm gap where a 20mm coupler (20 long x 12 OD with 5 ID) fits.
- Prusa have to make a difference between both kits, as the MMUv1 to MMU2v2 upgrade kit is €/$50 cheaper (normal price) than the complete MMU2 kit.
MMUv1 (2 and 4 changer) owners will be able to upgrade their MMUv1 kit reusing 2 Nema motors, which makes the €/$50 discount reasonable. Only additional things MMUv1 owners need is a ~90mm d-shaft + the coupler for the Pulley motor assembly.
Still wonder how the MMU2 control board will be connected to the MK25 miniRAMbo as the actual signal cable will connects it directly to the miniRAMbo reset line and not as on the Einsy to a controlled pin.
BOM difference between the MMUv1 to MMUv2 upgrade kit compared to the MMUv2 full kit:
-1x Idler motor
-1x Pulley motor
+1x ~90mm d-shaft
+1x coupler
maybe -4x spool holders
But we will see what will be shipped.
The only flaw in that otherwise perfect logic is that ones who only have two color have a total of 2 steppers. If you used those for the pulley and idler, you would not be left with one for the extruder. Just a thought. Kinda disapointed that we will have a coupler involved, but its not a really high precision process...sending filiment to be taken up by the extruder.
Re: MMU 2.0 upgrade kit details technical differences
I expect that the MMUv1 to MMUv2 upgrade kit will not contain the idler motor and pulley motor with the ~110mm long shaft because:
- The pulley body has a 22mm gap where a 20mm coupler (20 long x 12 OD with 5 ID) fits.
- Prusa have to make a difference between both kits, as the MMUv1 to MMU2v2 upgrade kit is €/$50 cheaper (normal price) than the complete MMU2 kit.
MMUv1 (2 and 4 changer) owners will be able to upgrade their MMUv1 kit reusing 2 Nema motors, which makes the €/$50 discount reasonable. Only additional things MMUv1 owners need is a ~90mm d-shaft + the coupler for the Pulley motor assembly.
Still wonder how the MMU2 control board will be connected to the MK25 miniRAMbo as the actual signal cable will connects it directly to the miniRAMbo reset line and not as on the Einsy to a controlled pin.
BOM difference between the MMUv1 to MMUv2 upgrade kit compared to the MMUv2 full kit:
-1x Idler motor
-1x Pulley motor
+1x ~90mm d-shaft
+1x coupler
maybe -4x spool holders
But we will see what will be shipped.
The only flaw in that otherwise perfect logic is that ones who only have two color have a total of 2 steppers. If you used those for the pulley and idler, you would not be left with one for the extruder. Just a thought. Kinda disapointed that we will have a coupler involved, but its not a really high precision process...sending filiment to be taken up by the extruder.
Totally forgot that the MMUv1 2 material just got one extra motor, thanks for pointing out my flaw 
There were some statements that the MMUv1 to MMUv2 will be the same as the full MMUv2 kit, but as said somewhere Prusa needs to make a difference between these two.
We will see what we get as soon 1st kits arrive at customers.