MMU2 Troubleshooting  

Re: MMU2 Troubleshooting

Well, I haven't run a test on it with the multi-colored benchy so I really don't know if I've fixed anything yet. Maybe I'll give it a whirl tomorrow.

Re: MMU2 Troubleshooting

what filament path is your black on?

Re: MMU2 Troubleshooting

Also, the MMU2 doesn't home on the right (past filament 5), it homes the selector by moving it all the way to the left (filament 1 position)

Now that is really strange. My MMU2 homes on the right, past filament 5. I don't believe that it ever hits the left hand side.

And having just checked it again, I can confirm that the body of the lead screw nut homes on the right wall of the selector body, past filament 5. Whilst at the right, it does 3 or 4 left-right movements to confirm the home position.

After homing, the selector moves to filament 1 and then to the selected filament position.

Peter

Re: MMU2 Troubleshooting

someone needs to add a 6th filament in the open spot 🙂

Re: MMU2 Troubleshooting

someone needs to add a 6th filament in the open spot 🙂

And where will the spool be positioned???

Peter

Re: MMU2 Troubleshooting

Also, the MMU2 doesn't home on the right (past filament 5), it homes the selector by moving it all the way to the left (filament 1 position)

Now that is really strange. My MMU2 homes on the right, past filament 5. I don't believe that it ever hits the left hand side.

And having just checked it again, I can confirm that the body of the lead screw nut homes on the right wall of the selector body, past filament 5. Whilst at the right, it does 3 or 4 left-right movements to confirm the home position.

After homing, the selector moves to filament 1 and then to the selected filament position.

Peter

I'll take a video of mine and post it so you can see what mine does. I did notice that the firmware upgrade I did changed how the MMU2 homed the selector - maybe we are running different firmware versions?

Re: MMU2 Troubleshooting

someone needs to add a 6th filament in the open spot 🙂

And where will the spool be positioned???

Peter

I have room on my cart, but ya it would start to get out of hand for most people.

I do remember seeing my mmu home left and right. but I don't think ive seen that in awhile.

Re: MMU2 Troubleshooting

I did just see it tap left side once. I might be on a older firmware. 1.0.3.212

Re: MMU2 Troubleshooting

FWIW, I asked the question:

When the MMU is initialising, does the selector home to the right (past F5) or the left (past F1)?

This was the reply:

right, homes and returns to left leaving small gap

Peter

Re: MMU2 Troubleshooting

It's so odd that my experience appears to be totally different than yours. Here is the video of my MMU2 homing. It doesn't even move to the right to home.

Who's your source for info, out of curiosity? If it's on the forum somewhere, maybe we can show them my video and they can explain what's happening - OR if I'm just perceiving the whole homing process wrong.

Re: MMU2 Troubleshooting

It's so odd that my experience appears to be totally different than yours. Here is the video of my MMU2 homing. It doesn't even move to the right to home.

Who's your source for info, out of curiosity? If it's on the forum somewhere, maybe we can show them my video and they can explain what's happening - OR if I'm just perceiving the whole homing process wrong.

My source is the MMU2 developer. As a beta-tester, I can still ask questions.

Your homing is just wrong. The selector should move to the right, tap on the right side a few times and then move to the left, stopping about 1mm short of the left edge (F1) and then move to the selected filament.

Could be that the firmware is wrong/bad?

But the thing is, you have a work-around, so it's up to you if you want to investigate further.

Peter

EDIT: I have passed on the YT link, so hopefully I will get a response for you.

Re: MMU2 Troubleshooting

Oh cool, that's a great resource to have in your back pocket - thank you!

I'm using firmware "prusa3d_fw_MMU2board_1_0_3.hex" from the Prusa webpage. I've flashed it a couple of times via Slic3r and the behavior remains the same.

I would very much prefer not to have that goofy shim installed in the MMU2 device. If we think back about my original post - the filament being forced into the bondtech gears, regardless of calibration (which is still an issue) and now that my unit is homing the selector wrong - there is something very much not right here, which is probably why I'm having so many issues with MMU2 unit. It basically doesn't work. Whatever help you can provide is very much appreciated.

Re: MMU2 Troubleshooting

So... I've been fiddling with firmware versions all evening. I have no success running 1.0.3 from the 3.5.0 or 3.5.1 firmware packages. If I run the 1.0.2 firmware, I have a 50/50 change that it will home correctly. I believe the issue is the stall detection provided by the trinamic drivers. It seems overly sensitive. While running 1.0.2, I get random "stutters" while the selector is moving to the right - if I get about 3 of them the MMU FW assumes it's hit the right side and moves the selector to the left, only to make the awful skipping step sound. Basically, if it homes correctly the first time - then I'm OK.

I saw an post about 1.0.4-RC1 firmware - just tried that and all of my homing issues appear to be gone. A new problem has arose though, and it's that selector is misaligned, to the right this time...

Anyway - more to come as I keep banging my head against this brick colored plastic wall.

Re: MMU2 Troubleshooting

Yeah, sorry, I haven't had a response as yet. Mondays are for meetings, so hopefully today.

But it does look as though you are getting somewhere.

The selector must be very tight on the rods. Just as a test, could you remove the brass bushes to see if it will home properly? (But don't try to print without them.)

Peter

Re: MMU2 Troubleshooting

Here's a couple of other things to try:

Double check that the upper rod is little bit moving in the mounting holes. Plus loosen the TR nut so it has a little bit of lateral play.

Peter

Re: MMU2 Troubleshooting

It's not a mechanical thing, I've taken everything apart and put it back together; all of it runs great. Firmware 1.0.3 is faulty - Comments are all over GitHub. The StallDetection routine in the code that drives the Trinamic drivers has issues because they are supposed to be run at a higher voltage than what the MK2.5 runs at. As a result FW 1.0.3 doesn't home right. FW 1.0.2 homes correctly about 50% of the time. FW 1.0.4-RC1 w/ hotfix homes correctly 100% of the time. As far as the filament bowden calibration length goes - that's still a mystery. It seems that folks are having a very difficult time between the 12V MK2.5 and the 24V MK3. The MMU2 installed on an MK3 printers seems to work w/o issue for many folks.

I think at this point I'll be dropping the homing issues on this thread - because it's clearly broken in the firmware. Once a version of firmware that works correctly is tested on my printer I'll come back here and let everyone know.

I appreciate everything everyone has contributed to me so far - this is a great community and it's really fun to engage and work out issues together.

Re: MMU2 Troubleshooting

Once a version of firmware that works correctly is tested on my printer I'll come back here and let everyone know.

Had the same observations, yesterday installed 3.5.2 and 1.0.4 (official version) and the homing issue is resolved for me. Maybe you could give it a try?
It does introduce unreliable Z calibration (9-point check before each print) for me as it reports errors often, that’s another topic.

Re: MMU2 Troubleshooting

Maybe you could give it a try?
It does introduce unreliable Z calibration (9-point check before each print) for me as it reports errors often, that’s another topic.

I'll be trying it over the weekend, at some point, and will report back.

Re: MMU2 Troubleshooting

Maybe you could give it a try?
It does introduce unreliable Z calibration (9-point check before each print) for me as it reports errors often, that’s another topic.

I'll be trying it over the weekend, at some point, and will report back.

I'm using Printer FW 3.5.2 and MMU2 FW 1.0.4. All of the MMU2 homing issues are gone! The MMU2 still forces way too much filament into the extruder - but I've solved that by making my own mechanical filament buffer based off of others ideas and posted it on Thingiverse for others in the event it's useful:
https://www.thingiverse.com/thing:3481492

I'm still having failed prints - but that's because the tips are not correctly formed and the long wisps of filament eventually fold over inside the PTFE tube and jams causing missed layers. There is plenty on the forum about forming the right shaped tips, so I don't think I'll bomb this thread with a whole new topic of issues (but will instead either make a new one or find one with good info).

Re: MMU2 Troubleshooting

Hi,
i'm a new owner of the MMU, and the first prints look really fantastic.

But I have a problem with the MMU Single Profil in Slic3r PE 1.4.2 Alpha 7, i think.
When i will start a print with a single color, the MK3 asks me wich filament it should load.
For example i choose filament 3. The MK3 start his bed leveling, then it loads the filament 3 and print the purge line.
At the end of the purge line it stops and the MMU will retract the Filament but the extruder of the MK3 holds the filament in place. 😕
Now the filament 3 has a damage and the MMU can't retract.

When i choose filament 1 everything works fine and the MK3 print the object.

Has someone the same problem?
Why does the MK3 don't use Filament 3?

When i choose the MMU Profil in Slic3r PE and the same filament (for example filament 3) on each object i don't need a purge block and the print works.

Firmware MK3: 3.6.0
Firmware MMU: 1.0.5

I hope this is the right place for my issue.

Tobias