Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...
 
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Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...  

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Milhooz
(@milhooz)
Trusted Member
Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

Two very simple improvements on the printer firmware that could save so many frustrations....

- Display the status of the IR sensor on the screen when loading (or better add a LED on the sensor so we can see that it is adjusted correctly)
- Why the heck is the extruder motor stopping right after the filament leave the gears? Make it turn until the filament has reached the FINDA so if it get stuck in the extruder gear, we don't have to open the extruder door....

 

PS: I had the MMU1, it did not work so well but probably because my filament was out of specs, I came to understand this only after receiving the MMU2. At least I've got a few prints out of it. Then I have got the MMU2 free on April 2019 because MMU1 was bad, and even so you said every where you have tested so much and it is working great, I've used it for about a week after receiving it and understand that it was still bad, even after the S upgrade, since one year, I have not printed a single time successfully a multiple color print, and PVA slicer profile is a joke, if you manage to print something by using the exact brand of the profile (PrimaSelect PVA+) and without tinkering with the profile, let me know, because it does not work. No I was pissed with even the normal single mode loading failing so many time I'm determined to make it work but adding improved parts (new custom printed parts, better PTFE, anything that could make it work) but honestly I love your brand, Prusa, I have a MK2, a MK3 and a Prusa SL1 but the MMU still sucks. You should remove it from the store and work on it again like you did for the MMU2 and be honest with your customers.

This topic was modified 4 years ago by Milhooz
Posted : 08/04/2020 9:32 pm
AndyInSwindon
(@andyinswindon)
Trusted Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

Good suggestions.  What irks me more than anything is that the MMU2S, when it works, is great, but getting it to do so is a matter of luck, patience, and sorcery.  And if you so much as criticise, you get jumped on by any number of people saying that it is all user error, and refusing to acknowledge that there mey, just may, be an issue with these units.  These issues exist in the wilderness that is Engineering.  Sometimes a product is just totall hit and miss with its reliability and repeatability.  I have had my intelligence, parentage, and eligibility for existence thrown into question for daring to say that the MMU2S is anything less than perfect.  If you bought a car that performed with similar characteristics, with the frequency of complaints that the MMU2S has, you'd be looking at mass product recalls, and the very real likelihood of the company going to the wall.  It's all very well that people say 'ah well you have to print this mod, make this adjustment, buy this part' etc, but again, if you bought a car, then had to buy and manufacture new parts to get it to run reliably, see how long you'd last.

I am not criticising those whom have had the patience, luck, experience and skill to get it to work well, well done to them, my point is, that in it's current advertised state, it shouldn't require all of that juju.

I can now sit here the rest of the night and wait for a hit squad of fanboys to come and assassinate me for saying anything less than it's a wonderful piece of kit.

Posted : 08/04/2020 10:04 pm
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bobstro
(@bobstro)
Illustrious Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...
Posted by: @apromain

[...] If you bought a car that performed with similar characteristics, with the frequency of complaints that the MMU2S has, you'd be looking at mass product recalls, and the very real likelihood of the company going to the wall.  

Or they'd call it a Jaguar. 

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 09/04/2020 1:27 am
nilok
(@nilok)
Estimable Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...
Posted by: @bobstro
Posted by: @apromain

[...] If you bought a car that performed with similar characteristics, with the frequency of complaints that the MMU2S has, you'd be looking at mass product recalls, and the very real likelihood of the company going to the wall.  

Or they'd call it a Jaguar. 

I haven't laughed that hard in days!

Is your printer grinding? Bearings squeaking? Motors smoking?
Step 1) Wash your Steel Sheet
Step 2) Return to Step 1

Posted : 09/04/2020 1:38 am
stephen.h14
(@stephen-h14)
Estimable Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...
Posted by: @bobstro
Posted by: @apromain

[...] If you bought a car that performed with similar characteristics, with the frequency of complaints that the MMU2S has, you'd be looking at mass product recalls, and the very real likelihood of the company going to the wall.  

Or they'd call it a Jaguar. 

A guy I used to work with asked "Why do Brits drink their beer warm?"

"Because Lucas makes refrigerators over there too!"

Posted : 09/04/2020 5:02 pm
Nikolai
(@nikolai)
Noble Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...
Posted by: @apromain

... And if you so much as criticise, you get jumped on by any number of people saying that it is all user error, and refusing to acknowledge that there mey, just may, be an issue with these units. ...

None of this answers would be good answers.

This is from community to community forum. The best thing you can get here are suggestions how to make your unit work, gain some knowledge or even ready to try some mods/software.

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram

Posted : 09/04/2020 11:27 pm
AndyInSwindon
(@andyinswindon)
Trusted Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

@nikolai-r

TBH compared to many other user groups and forums, I must admit that I have found this particular resource to be far more helpful, less judgemental and less 'nasty' than many others, such as some of the Facebook forums.

 

Posted : 10/04/2020 2:52 pm
Nikolai liked
pcweber
(@pcweber)
Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

@apromain

Hey man, no assassination required not here during these times at least. I got blasted by one of the techies there in Praque, he kinda ignored me and sent me on the proverbial wild goose thingy. I got pissed and pulled my mmu2s apart, carefully inspecting each part. There is where I encountered an anomoly in the parts that come with the MMU. Precisely the idler drum, it must've had minor warping which I located spinning the drum by hand. The side part where the pulley motor is attached moved, kind of wavy and back and forth. This part should only have movement along the center axis and the motor shouldn't move.

I printed another idler barrel with petg, black, but that only adds to the contrast of the mmu. When I put it all back together there was not any movement other than the center axis. I spent two and a half frustrating months trying to get it to work.  I had done all of these mods to reduce friction into the unit, they're still in place though now probably overkill. The unit pulls really hard on the filament now and there is a noticeable difference when I adjust the tensioner screws.

Early on I had to remove the knife from the selector since with all that wobble it dug into the unit parts. After reviewing the upgrades on git-hub I noticed the new selector and printed it. The knife works like it should now. But I just worked the kinks out of the printed part. You see the steel bearing in the Finda detector hung on some filament ends.

Today I sanded the section with 800 grit sandpaper and pushed some oversized filament, woodfil, through it until there was no friction. I still had a weird blinking led issue, I did a clean up of the connectors and paid particular attention to the wiring, eliminating movement of the wiring bundle by the movement of the FINDA probe. This followed up with a verification of the sensor detection, it was dirty giving intermittent results almost impossible to detect. The unit looks good, I did several loads to nozzle checks with perfect results.

I am confident that it will work so now I need to do a multi-material print. Even with my confidence factor, I'll still keep my fingers crossed. I am envious of those individuals who gloat about prints with 500 or more tool changes; however, if they can do that so can I. If the latest actions that I performed do not do the trick, I suppose that I'll get back into the trenches until I get there.

 

Best regards and good luck, BTW stay safe,

Phil

Stay safe and healthy, Phil

Posted : 11/04/2020 4:13 pm
stephen.h14
(@stephen-h14)
Estimable Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...
Posted by: @pcweber

.....There is where I encountered an anomoly in the parts that come with the MMU. Precisely the idler drum, it must've had minor warping which I located spinning the drum by hand. The side part where the pulley motor is attached moved, kind of wavy and back and forth. This part should only have movement along the center axis and the motor shouldn't move....

That may or may not be the smoking gun? It might explain why some users are easily successful out of the gate and some users struggle?

Would it be worthwhile to check the runout on a few units that work well and a few that are having issues and see if there’s a trend?

This post was modified 4 years ago by stephen.h14
Posted : 11/04/2020 7:20 pm
pcweber
(@pcweber)
Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

Well the maligned barrel presented many errors that everyone who's having troubles appear to coincide with some of the errors I had. In addition, I had no idea how this unit was supposed to operate, making it impossible to correct without a reference.

It's a shame I didn't take a video of the error. I just didn't know if the barrel replacement was the root cause. Since the techie blew me off.

To answer your question, there was a rise in errors on this forum with units shipped in January. The barrel is PETG making it susceptible to drafts. Manually spinning the pulley with the steppers off or the machine powered down and the simply observing the movement along the axis will verify if  there's an alignment issue. So a sampling of kits shipped in January may clear up issues. 

 

Best Regards and Be Safe

 

Phil

 

 

Stay safe and healthy, Phil

Posted : 11/04/2020 9:30 pm
AndyInSwindon
(@andyinswindon)
Trusted Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

This is nicely constructive, and could explain a lot.  Every time I see a thread from someone struggling with an MMU2S, especially if they criticise it's readiness for market, I see them get shot down in flames and torn to pieces, but, this thread could be illuminating.  There may be a lot of people under the impression that they have tuned the unit to perfection, and that other lesser beings are lacking in intellect or ability, when it may simply be a quality control issue that no one has picked up on before.  So those struggling are vindicated as they are fighting a losing battle.  Just a thought.

Posted : 12/04/2020 4:50 pm
pcweber
(@pcweber)
Member
RE: Message for Prusa developers: Two easy firmware improvements that make the MMU2 acceptable...

@apromain

This is why I've tried to share my experiences with the MMU and what ultimately fixed the issues. Getting your support is great feedback, I'd hoped to get through to somebody and that by posting it it helps others with similar problems. 

 

Best Regards and stay safe, 

 

Phil

Stay safe and healthy, Phil

Posted : 12/04/2020 7:47 pm
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