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I've about had it with the MMU 🙁  

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jason.m9
(@jason-m9)
Active Member
I've about had it with the MMU 🙁

Printed single extruder for a long time, upgraded to the MMK about 6 months or so ago, nothing - and I mean NOTHING but problems since.

First, most annoyingly, I have 4 profiles setup for single extrusion prints, each of those profiles as a T<extruder number> (e.g, T0, T1, T2, T3), the generated GCode looks fine, except after the printer Start GCode and right before the Filament GCode, after all the stuff that is *supposed* to be outputed, there's a hard coded T0 coming from somewhere, and from where, I have no idea...

Example, I want to print with the 2nd extruder, which is set correctly, then reset back to 1:


M107
M115 U3.1.0 ; tell printer latest fw version
; Start G-Code sequence START
T1
M104 S250
M140 S75
M109 S250
M190 S75
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
G28 W
G80
G92 E0.0
M203 E100
M92 E140
G1 Z0.250 F7200.000
G1 X50.0 E80.0 F1000.0
G1 X160.0 E20.0 F1000.0
G1 Z0.200 F7200.000
G1 X220.0 E13 F1000.0
G1 X240.0 E0 F1000.0
G1 E-4 F1000.0
G92 E0.0
; Filament gcode - Hatchbox Black ABS

THIS BLOCK OF CODE, HERE, I HAVE NO IDEA WHERE IT COMES FROM
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
T0

; Filament gcode - Hatchbox Black ABS
;BEFORE_LAYER_CHANGE
;0.4

If I use the default single mode printer config (that has the T? line in it), it doesn't default back to 0.

Change that '?' though and it will...

I'm constantly having to unload and reload all 4 filaments between prints, if I want to switch extruder. It's like there's nothing that pulls the loaded filament back after the print completes to get it out of the way for the next print - *IF* you so happen to want to switch extruders. If I use the same one, no big deal.

Jams - holy crap. It's like every test print I do, which I have to do often to make sure all the temps are set right, work, but the *real* prints, only like 1 in 5 work. Sometimes the jam happens many hours later, sometimes right away, every once in a while not at all. And the jams are anywhere from the steel nozzle to the PTFE tube going into the hotend.

Now, I admit, the jams usually happen when either working with all ABS or using ABS as a support for Nylon (which, actually works VERY well, WHEN it works). I know that's not a supported setup, but damn! This shouldn't be called a multi MATERIAL upgrade, more like a multi COLOR (but same material) upgrade.

My success rate has dropped to below 30%, I've wasted a ton of filament, and I have no hair left.

Before the MMU I calibrated the printer and never had to touch it again,m except to load / unload it. Now, I mess with it all the time, it's almost to the point of insanity. I'm very nearly to the point of buying another printer just for single mode prints, which I do far more often than multi color / material.

So, first, any idea where that T0 is being injected at? As of now, I have to export the gcode to a file, edit that out, then upload it to Octoprint.

Second, any idea on how to resolve some of my jamming issues? Any idea on how to fix the not-retracting-filament-after-a-print issue?

Running the latest MMK firmware and the latest Slic3r.

Sorry if this is coming across as harsh, I've been fighting this for a long time, it's rare that I can start a multi-COLOR print and just walk away from the printer. I'm aggravated and frustrated.

Posted : 12/01/2018 6:33 pm
ntdesign
(@ntdesign)
Reputable Member
Re: I've about had it with the MMU 🙁

I've also had the T0 issue. It finally went away after I reinstalled slicer, deleting all settings before reinstalling (!). Then I selected MK2S/MMU in the wizard after reinstall. Maybe things got mixed up with single printer settings. Latest Version (MacOS).

Posted : 12/01/2018 6:57 pm
jason.m9
(@jason-m9)
Active Member
Topic starter answered:
Re: I've about had it with the MMU 🙁

I'll try removing everything, I have a folder with each new version of Slic3r, never really got rid of the old ones, bad habit....

After reading here a bit, seems I'm not the only one going insane over here, lol... 🙁

Posted : 12/01/2018 7:06 pm
ntdesign
(@ntdesign)
Reputable Member
Re: I've about had it with the MMU 🙁

Lol, it just happened again after lots of successful prints. What I did was switch to 0.2mm NORMAL and filament to generic PETG and the T0 was back. No other changes.

Posted : 13/01/2018 3:55 pm
jason.m9
(@jason-m9)
Active Member
Topic starter answered:
Re: I've about had it with the MMU 🙁

I've now had 5 failed prints (single filament), IN A ROW, with NylonX, not exactly the stuff I want to be just throwing on the floor. This is absurd, and what's more alarming is the lack of representation from the makers of the most popular reprap in the world....

I ought a Prusa thinking I was getting a printer I wouldn't constantly be farting around with, otherwise I would have sourced parts and built my own. Between helicopters, quadcopters and RC stuff, I have enough crap to muck with, was hoping the printer would be much more solid than this.

I'm printing the redesigned tubeless muxer, in transparent PETG, see if that will fix it, or at least let me see what the issue is.

Slic3r, just today, started crashing on me anytime I use one of the non-included printer profiles, just today, no changes. I wish I could find reliable profiles for Cura or S3D.

Posted : 13/01/2018 4:25 pm
louis.o
(@louis-o)
New Member
Re: I've about had it with the MMU 🙁

I agree with you. I've had nothing but problems since upgrading to mmu as well. I get lots of filament jams. The mmu is not worth it!! 😥 😥

Posted : 13/01/2018 5:52 pm
seth.g2
(@seth-g2)
Trusted Member
Re: I've about had it with the MMU 🙁


I've now had 5 failed prints (single filament), IN A ROW, with NylonX, not exactly the stuff I want to be just throwing on the floor. This is absurd, and what's more alarming is the lack of representation from the makers of the most popular reprap in the world....

I ought a Prusa thinking I was getting a printer I wouldn't constantly be farting around with, otherwise I would have sourced parts and built my own. Between helicopters, quadcopters and RC stuff, I have enough crap to muck with, was hoping the printer would be much more solid than this.

I'm printing the redesigned tubeless muxer, in transparent PETG, see if that will fix it, or at least let me see what the issue is.

Slic3r, just today, started crashing on me anytime I use one of the non-included printer profiles, just today, no changes. I wish I could find reliable profiles for Cura or S3D.

Save your effort and just try the monoplexer in this thread first, it's a way easier downgrade and I found it took away a ton of problems.

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801-s40.html

As far as the jams you mentioned in your first post, the redesigned multiplexer in the same thread made a huge difference for me, I have zero jams now in over a dozen prints, some lasting over 30-50 hours.

As far as your slic3r woes go, I haven't tried to use the single mode, what I usually do is always use it in multimaterial mode and set my extruders up that way. I haven't experienced the t0 problem you're having, and I don't like to mess with gcode manually if I can help it, but why couldn't you just set it up as a multi material print but only use a single color?

From what you were saying, you wanted it to use one extruder for a little, and then switch after a bit. Are you printing raft layers or something?

Sorry if it seems like I'm over simplifying, I can tell you've been pulling your hair out over this.

Posted : 14/01/2018 4:02 am
jason.m9
(@jason-m9)
Active Member
Topic starter answered:
Re: I've about had it with the MMU 🙁



I've now had 5 failed prints (single filament), IN A ROW, with NylonX, not exactly the stuff I want to be just throwing on the floor. This is absurd, and what's more alarming is the lack of representation from the makers of the most popular reprap in the world....

I ought a Prusa thinking I was getting a printer I wouldn't constantly be farting around with, otherwise I would have sourced parts and built my own. Between helicopters, quadcopters and RC stuff, I have enough crap to muck with, was hoping the printer would be much more solid than this.

I'm printing the redesigned tubeless muxer, in transparent PETG, see if that will fix it, or at least let me see what the issue is.

Slic3r, just today, started crashing on me anytime I use one of the non-included printer profiles, just today, no changes. I wish I could find reliable profiles for Cura or S3D.

Save your effort and just try the monoplexer in this thread first, it's a way easier downgrade and I found it took away a ton of problems.

https://shop.prusa3d.com/forum/original-prusa-i3-mk2-multi-material-f26/monoplexer-and-multiplexer-redesigns-no-metal-part-t12801-s40.html

As far as the jams you mentioned in your first post, the redesigned multiplexer in the same thread made a huge difference for me, I have zero jams now in over a dozen prints, some lasting over 30-50 hours.

As far as your slic3r woes go, I haven't tried to use the single mode, what I usually do is always use it in multimaterial mode and set my extruders up that way. I haven't experienced the t0 problem you're having, and I don't like to mess with gcode manually if I can help it, but why couldn't you just set it up as a multi material print but only use a single color?

From what you were saying, you wanted it to use one extruder for a little, and then switch after a bit. Are you printing raft layers or something?

Sorry if it seems like I'm over simplifying, I can tell you've been pulling your hair out over this.

You da man....

I printed your version of the multiplexer, used some NylonX I had laying around that had extruder ribs in it to 'clearance' the holes, and am 8 hours in to a dual NylonX/ABS print, which never worked and would jam either off the get go or within 10 layers. Only 30 hours left to go to see this thing finish, for once.

I hope I'm not shooting myself in the foot, but much, much better just in this short period of time. If this works, it'll save me a ton of frustration AND money, using ABS as supports for NylonX is AWESOME when it works (and it's only worked on test prints so far). I can set the contact distance to 0 (soluble) and get a nice, clean, hassle free support removal from the NylonX. The part I'm printing right now, a cover for a quadcopter I'm designing, uses about 130Grams of filament for the cover and over 200 for the supports, so this working saves a bunch of money (and hair / frustration)...

As for the Slic3r issues, I actually went down the path you recommend, just using the Multimaterial profile, I just always forgot to go change extruder settings in the print tab. So, I made 4 Single mode profiles, one for each extruder, and when I want to use the printer in single filament mode, I just select the printer profile that has the extruder I want to use. As far as workflow goes, that seems to be the better option, for me, because I always check the profiles before sending the print off to Octoprint.

I have profiles setup for all of the filaments (of course), and every single print setting I use routinely (speed, infill, layer height, infill type, supports, etc) - I have a lot, names in a way that makes sense to me, but it makes it so I only have to muck with the individual tabs when I want a one off setting, most times II load the part(s), arrange them, select the profiles and go...

What you suggest DOES work, as does leaving T? in the single mode profile, it's just a convenience thing and workflow thing, for me.

Posted : 14/01/2018 6:50 am
seth.g2
(@seth-g2)
Trusted Member
Re: I've about had it with the MMU 🙁

It seems that it completely fixes about 50% of people's problems on the forums. The other half have problems south of the multiplexer as well.

Good luck with your future prints, always keep us updated on progress, even if it's good.

Posted : 15/01/2018 12:11 am
jason.m9
(@jason-m9)
Active Member
Topic starter answered:
Re: I've about had it with the MMU 🙁

Guess I spoke too soon... DAMMIT.. @#$%(#@$ (&#$@(% !@(

The ABS, and it seems to ALWAYS be the ABS that has problems, actually broke off right where all the 'channels' meet. I had to get in there with a tiny drill bit and some tweezers to get the little ass piece that broke off.

I might try lowering the ABS temp a bit to see if that helps. Perhaps the swing from 260 for the Nylon down to 235 for the ABS might be a bit much.

Either way, this multi material thing is great for novelty, but proving to not be a great idea when it comes to actually making real parts. I wish I'd have bought a second printer instead of this upgrade.

And, I get that we are kind of on the front line here, the pathfinders, I get it. This is new, we bought a product on it's first revision. That doesn't excuse, at all, the total silence from Prusa. They should be all over these threads trying to resolve the issue, find the root cause and get a V2 out that actually works. If that were happening, I'd feel a little better about being an early adopter. As it stands now, I feel like I handed a fist full of cash over to someone who skipped town on me the next day 🙁

Posted : 15/01/2018 12:20 am
seth.g2
(@seth-g2)
Trusted Member
Re: I've about had it with the MMU 🙁

You're not alone, there are a ton of people who feel exactly the same way, and you're not wrong either.

What did you print the multiplexer out of?

I would suggest making sure the feed paths are fully broken in to help avoid jams, mine had 1 or 2 jams for the first day or two, and nothing since then.

I'm hearing that using different kinds of materials has caused problems for some people. My understanding is that multiple colors are easy to print, multiple materials are a little more involved. I'm guessing that a lot of it has to do with getting your slic3r setting dialed in for your filaments and extruders and how it handles switching between them before you start experiencing less problems.

Posted : 15/01/2018 2:10 am
jason.m9
(@jason-m9)
Active Member
Topic starter answered:
Re: I've about had it with the MMU 🙁

I printed it out of PETG, the only clear filament I have (turns out, I can't see into the feed tubes anyway). I don't have any PLA, so choices are ABS (what I use mostly), PETG and NylonX. I figured the nylon would be TOO durable to be broken in.

Yeah, I'm starting to just admit defeat trying to print Nylon and ABS together, sure does make an awesome way to do support structures though - when it works. I'll let the multiplexer break in a bit and try again in a few days. I have some pretty big all nylon parts I'm printing now, it should be broken in nice by the time I'm done :)..

Posted : 15/01/2018 5:55 am
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