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MMU still just not ready for sale  

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JoanTabb
(@joantabb)
Moderator
Re: MMU still just not ready for sale

Keep looking back here Jesper, there might be a game changer that resolves the outstanding issues.... but don't hold your breath...

regards Joan,

waiting but breathing normally.

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 05/01/2018 4:13 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: MMU still just not ready for sale

Prusa vs Ultimaker. Thats comparing apples to oranges.

For one, the price difference.

What frustrates me the most is that I just want to print PETG/PLA + soluble supports. I don't care about 4 color printing.

I am in the same boat as others here. Thinking of kicking out the mk2sMMU, have an mk3 on order, and getting something like a BCN Sigma to do the dual extrusion prints.
Too bad the high end printers all use 2.85mm filament. I have tons of 1.75, including BVOH and PVA. Expensive switching if you ask me ...

Posted : 05/01/2018 5:13 pm
mavu
 mavu
(@mavu)
Estimable Member
Re: MMU still just not ready for sale




UNTRIED ADVICE FOLLOWS - I HAVE NOT TRIED THIS

The interior surface of the PTFE tube seems to be a big deal in this application. And specifically the inner tolerances. Prusa has talked about these tubes being special made for them. If that is where your jams have been, it might be worth trying a "Capricorn" tube.

https://www.captubes.com/shop/
https://www.captubes.com/specs.html

I tried that... not a solution for me

I installed capricorn xs tubes at the same time I upgraded to the latest firmware with linear advance, and my stringing problems are gone.
BUT I have not printed a lot since, and I can't tell if it was the new firmware and slic3r or the tubes or both.

Still, I absolutely agree on the general issue with the MMU. It feels very much like the un-loved step child.
Very little support for it.
Still no real Slic3r spport for color layer switching.
No official progress on actual multi-material printing beyond PETG/PLA which is the most boring combination. (no flexibles without extensive profile modification, no updated extruder with more constrained filament path...)

And most importantly : No word on it after the release. No confirmation of issues, no word on further plans for it except it showing up on the MK3 shop page.
No update on what they are working on concerning the MMU (if anything)

And btw, if anyone mentions facebook support groups: If I need to use facebook to use a product, I want to know that before I buy it. Because then I wont buy it.

Posted : 06/01/2018 10:58 am
ntdesign
(@ntdesign)
Estimable Member
Re: MMU still just not ready for sale

For what it's worth, mine more or less works now (after taking everything involving the filament path apart at least twice, tweaking every conceivable setting, reworking and/or replacing several parts etc.). I've done about 10 MM prints (2-4 colors) > 12 hours, an endless army of single Marvins and a couple of 24+ hours single prints. I trust my machine again for PLA and PETG.
I have stringing problems like so many others, but the strings are fine enough to blow off with a quick sweep from a heatgun. I'm trying to find the sweet spot, in my case it's definitely the retraction length. Too long and I get jams below the PTFE, too short and I get instant stringing. I more or less managed 98A Flexfill, prints could be prettier but it'll do. I feel extremely reluctant to dip into multi-material and PVA.

In summary I would say considering the amount of time and filament I wasted, and the staggering number of frustrating moments, I would not buy this again and rather invest in a 2000+USD dual head printer like the Sigma. My free time is valuable to me and this quickly stopped feeling like a fun challenge and started to feel like (boring) work. Actually I spent lots of time over the holidays to improve my old CoreXY. It's unsexy as hell, but gets the job done. No fiddling, no need for elaborate sensors, no firmware tweeks, no terrible hissing 30mm fans, no bitchy clicking Bondtechs. I'll use my leftover MK2S hotend to build a smaller one geared towards quiet&reliable I can keep at home. No MK3 for me, I'm done. Honestly I think the Prusa design has moved too far from the original design goals and is now trying hard to patch up the deficits. You pay for the software infrastructure and the "it just works" feel, which is alright by me but simply not existant for the MMU.
At this price point you can easily build a cubic printer, direct or Bowden by preference. Stick a reliable board with Trinamics and a V6 in there, use proper bearings and rods and well-designed mechanical levelling (i.e. get rid of the Z sensor) and you end up with a foolproof, quiet and durable machine that can be run by a kid.

I really hope PR learn from this experience. Announcing the MM for MK3S was a big mistake IMHO, unless they already have a miracle cure they don't want to share right now. Just my 2cents, no hard feelings.

Posted : 06/01/2018 2:17 pm
Zwirbel
(@zwirbel)
Re: MMU still just not ready for sale

After reading through this topic, it seems to me that this problem is just ignored by Prusa. I have exactly the same problem after upgrading my MK2S to MM:

Material: PLA material from Prusa, grey. I have successfully printed a lot before the MM upgrade and never faced this problem.
Do someone have some hints on what could be improved to get (even partially) rid of the problem?

Posted : 06/01/2018 7:05 pm
seth.g2
(@seth-g2)
Trusted Member
Re: MMU still just not ready for sale

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801.html

This worked for me.

The only other thing I've heard that helps stringing is retraction distances in your gcode or slic3r settings you could do a search on the forums and find a number of topics about it.

Good luck!

Posted : 06/01/2018 11:05 pm
ntdesign
(@ntdesign)
Estimable Member
Re: MMU still just not ready for sale

What worked for me with PLA (original PR, Fillamentum, esun, Noname and Polymax tested):

Following changes to defaults: Retract speed 50, Deretract speed 30, First layer 205°, second layer 200°.
I started with 2.8mm retract length (I think suggested by Joan) to assure I don't get blockage. Single color Marvin with low infill at 0.15mm is good for that (many retracts), it will fail at about eye height when retracts are too long. Try several different spools and for further tests use your most terrible filament (I have a spool with very uneven diameters from PR). Then increase retract length in 0.2 mm steps until it fails, then go back 0.2. I did that today and it looks good, I ended up at 4.0mm. No MM testing yet, but the other settings worked reliably for me at 2.8 mm so probably the results can be transferred. Yes this took many many prints. The same retracts settings worked for me with PETG and 98A, leaving mainly temps and cooling as parameters for these.

Make sure you did proper PID calibration first, have well-seated steel tubes and as little force on the Bondtechs as possible (I released each screw while printing a slab until it slipped, then turned back half a turn). Make sure there is ZERO PLAY on the Festos. I also had to cut and rechamfer my PFTE (it was too long by 1 mm), as well as disassemble the hotend (nozzle was improperly seated - this removed one major source of blockage). Both are probably not necessary for you since it seems like you can at least print.
My printer is unmodded, but something must definitely be done about part cooling. The backside of parts could be much improved.
Hope this helps, good luck.

EDIT: I couldn't raise MM retracts above 3.2mm without clogging, leaving me with the stringing problem. However, there was a new Slic3r version released by PR this friday. I'm testing it now and it looks promising. I cannot tell what they changed but maybe something was done about linear advance. I'm about 30 minutes into a 2 color treefrog, with hardly any stringing.

Posted : 06/01/2018 11:39 pm
bert.v6
(@bert-v6)
Eminent Member
Re: MMU still just not ready for sale


https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801.html

This worked for me.

The only other thing I've heard that helps stringing is retraction distances in your gcode or slic3r settings you could do a search on the forums and find a number of topics about it.

Good luck!

Unfortunately, not for me :

I think it is a shame that Prusa sells this kind bad imature products of for good money.

Posted : 07/01/2018 4:27 pm
bert.v6
(@bert-v6)
Eminent Member
Re: MMU still just not ready for sale

The only reason I wanted MMU for is to use the water soluble filament.

Well, I am done with it and wrote an email to Prusa:

I hope it helps.

Posted : 07/01/2018 4:39 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: MMU still just not ready for sale

Let's not get started about cooling.

There are huge cooling issues with the fan blowing only at the front.
I just did some PETG tests and the difference the part orientation makes is just crazy.
I don't understand why Prusa doesn't simply provide an upgraded cooling part (even by stl file). The worst is they realise it's not good since they completely changed the cooling system on the MK3...

Posted : 07/01/2018 7:11 pm
ntdesign
(@ntdesign)
Estimable Member
Re: MMU still just not ready for sale

Well Joris, have you seen a single comment about all the MMU issues by any PR mod in the last months? Last I remember was Jakub stating on page 4 or so of the blockage thread that "everything will be fine..."
I think we are being ignored. I kind of understand why, if they stopped selling the MMU now, people would come banging down their door asking for a refund. Imagine what happens to MK2s/MMU support once they start selling the MK3 MMU.

Posted : 07/01/2018 7:31 pm
bert.v6
(@bert-v6)
Eminent Member
Re: MMU still just not ready for sale

You can see this happen right now. I have tested the latest driver version 2.1.3. It only provides upgrades for MK3.

I have tested it, no real improvement.

Posted : 07/01/2018 10:54 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: MMU still just not ready for sale

This is my fear too.
That the focus is on the mk3 and readying the mk3 MMU, and that mk2s user problems have been shifted to the back of the queue 🙁

Posted : 07/01/2018 11:07 pm
ntdesign
(@ntdesign)
Estimable Member
Re: MMU still just not ready for sale

Over the ledge, more like it. If I had a support-intense product, I wouldn't support it on two platforms. Especially if it is considered high end. Best we can hope for is some small printed upgrades from the MK3 MMU that are downwards compatible or a way to carry over existing MMU parts to a MK3. I don't really see the point of the filament sensor upgrade at this point either, with the way prints usually fail it wouldn't help.

Posted : 08/01/2018 9:13 am
HKOCH
(@hkoch)
Topic starter answered:
Re: MMU still just not ready for sale

Another sad thing in this MMU story is that nearly every person needs to set their temperatures of of spec from the Filament. Even Prusa preferred filament can't be printed using the default temperatures. Two things are wrong in that!:

1) If that's the case. Why isn't these settings the default in Sli3er ? When you select the printer as a one with MMU
2) Filament manufacturers spec's which temperature span to print their filaments in between. Why do you have to go of of spec with filaments when printing with MMU. Even also when using the Prusa filament? The reason of making spec. for filament is of course to tell people where this filament has the best characteristics as stringing, flow, melting temperature, and other atomic parameters. So why print outside these - that sounds like a bad idea.

Again this tells me - Prusa stop selling the MMU to anyone. This design is so bad that you will just get more frustrated customers over time. This is simply not good enough for sale. ❗

Trust me, i'm an engineer ! PRUSA: Always do your best. What you plant now, you will harvest later

Posted : 08/01/2018 10:04 am
malcinator
(@malcinator)
Trusted Member
Re: MMU still just not ready for sale

My thoughts of the MK2 were super high and I had fantastic results print after print. So why not purchase the MMU upgrade I though, hey the few Youtube vids showing it off convinced me that the awesome MK2 would just be more awesome with the MMU. I was making some money from 3D Hubs, which is what I used to pay for the upgrade. Life with my Prusa was good.

How naive I was looking back, what a fool.

I have been fighting with my MMU ever since I made the mistake of purchasing it. I have had a few decent prints and lots & lots & lots of failed prints. I have rebuilt my hotted more times now than I care to count due to jams & clogs. Now I spend more time unblocking it than printing. My income from 3D Hubs is zero and has been for months now. If it wasn't for the fact that it was an expensive upgrade I would have removed it, in fact I really want to but just for some reason I can't actually do it. Yet.

My thoughts of my MK2 are the complete opposite now. The MMU is definitely not ready for release it's a beta product at best. The lack of youtube vids showing off the MMU are few and far between which speaks volumes to me. If it was as good as the hype there would be thousands of them.

I agree that Prusa should get involved with support here and help out us frustrated MMU users. The longer these treads get increases the damage being done to the Prusa Brand by ignoring the problem. I feel this is something that will come back round and bite them.

Posted : 11/01/2018 3:52 pm
HKOCH
(@hkoch)
Topic starter answered:
Re: MMU still just not ready for sale

I have now several times tried to add a review on the shop for the MMU. This are being neglected by the moderator. Prusa doesn’t seem to like negative feedback. This becomes more and more worse for the reputation of Prusa 🙁

They don’t allow new unknowing byers to become aware off the issues before they go into the trap, but prefer to sell the totally unreliable solution - maybe to make profit instead of satisfied customers - really really sad! ❗ ❗ ❗

Trust me, i'm an engineer ! PRUSA: Always do your best. What you plant now, you will harvest later

Posted : 11/01/2018 11:56 pm
seth.g2
(@seth-g2)
Trusted Member
Re: MMU still just not ready for sale


My thoughts of the MK2 were super high and I had fantastic results print after print. So why not purchase the MMU upgrade I though, hey the few Youtube vids showing it off convinced me that the awesome MK2 would just be more awesome with the MMU. I was making some money from 3D Hubs, which is what I used to pay for the upgrade. Life with my Prusa was good.

How naive I was looking back, what a fool.

I have been fighting with my MMU ever since I made the mistake of purchasing it. I have had a few decent prints and lots & lots & lots of failed prints. I have rebuilt my hotted more times now than I care to count due to jams & clogs. Now I spend more time unblocking it than printing. My income from 3D Hubs is zero and has been for months now. If it wasn't for the fact that it was an expensive upgrade I would have removed it, in fact I really want to but just for some reason I can't actually do it. Yet.

My thoughts of my MK2 are the complete opposite now. The MMU is definitely not ready for release it's a beta product at best. The lack of youtube vids showing off the MMU are few and far between which speaks volumes to me. If it was as good as the hype there would be thousands of them.

I agree that Prusa should get involved with support here and help out us frustrated MMU users. The longer these treads get increases the damage being done to the Prusa Brand by ignoring the problem. I feel this is something that will come back round and bite them.

Jams were my number one problem as well.

I still highly recommend printing my redesigned Splitter if you haven't already. I haven't had a jam since.

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal

I'm not the only one who has had success, even people who weren't having catastrophic problems have compared mine to the original and had better results with the redesign.

It's seriously worth a try if you have come this far! The MMU is awesome when it functions correctly!

Posted : 12/01/2018 12:03 am
Laird Popkin
(@laird-popkin)
Estimable Member
Re: MMU still just not ready for sale

Wow, I love the idea of the MMU. I have a new Mk3, and ordered the Mk3 MMU, but now I'm wondering if I should cancel the pre-order and wait for the design to mature.

Specifically, what I am interested in is mixing different materials with different properties (rigid vs flexible vs dissolvable support). I've had some good results on a dual extruder printer, and was hoping that the MMU would work even better, since its design avoids the dripping from the idle extruder.

So two questions from people with the MMU:
- Does it work as well as the single extruder Mk3? (Which is AWESOME!) Clearly there are some issues - but once you get it working, is it as consistent and reliable as the single extruder?
- Can it print flexible filament? (NinjaFlex, etc.) Prusa says it does, but I've never had any luck printing flexible filament on a Bowden printer. Am I being too cynical?

Posted : 12/01/2018 1:14 am
victor.l4
(@victor-l4)
Active Member
Re: MMU still just not ready for sale

honestly, just wait. do not purchase yet..

Posted : 12/01/2018 5:35 am
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