MMU 2 two color print - purge block with strings and blobs
Hi!
Doing a two color 3d print with Prosa PETG with my Prusa i3 MK3 MMU 2.0 I discovered some problems mostly on the side of the purge block.
While the surface of my two color 3d print is okay (also not perfectly smooth) I can see the formation of strings on the purge block (see attached photos)
The whole 3d print lasted 2 hours, during this time I also had to remove manually one big blob developing on the purge block.
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In the past during one color prints, I did see similar errors which I could solve by changing the distance between nozzle and printer.
Do you know possible reasons for my observation?
Can the formation of the purge block result the problems?
In my two-colour print I had several layers with only one color. I assume that in this situation the height of the purge block cannot reach the same height as the two color 3d print. During the formation of the purge block I had the impression that not each layer is completely filled. Could this lead to my problems?
I’m afraid that the bad quality of the purge block will for longer prints prevent a good result of my 3d print.
Thank you for any helpful comments!
Best
Frank
Re: MMU 2 two color print - purge block with strings and blobs
I'm having a similar issue. I'm using the MMU2S which otherwise is working flawlessly, but creates lumpy blobs on the surface of the purge block where it pauses to switch filaments. The nozzle keeps catching these bumps and eventually dislodges the purge tower from the the build surface.
I'm using Prusament Black and Silver PLA.
Chat support have advised me to reduce the Wipe Tower "Maximal Bridge Distance" in Slic3r PE. I'm not sure exactly how that will reduce these blobs, but I'm giving it a go.
Re: MMU 2 two color print - purge block with strings and blobs
Thank you for your comment. I will have to repeat my print to see if my observation is reproducible.
What you describe sounds similar to what I have seen, but I don't know if it has the same reason.
I will write how my next print will be.
Best Frank
Re: MMU 2 two color print - purge block with strings and blobs
Is this with the "S" version or the non-"S"?
They are different printers with different load parameters and the correct printer must be selected within Slic3r
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: MMU 2 two color print - purge block with strings and blobs
Thanks Peter - Mine is the MMU2S - and my problem was entirely user error on my part. I spotted last night that I'd accidentally selected the wrong Slic3r profile (the MMU2 instead of MMU2S) - a couple of tests later and my blobbing problem is solved. I guess the problem was the design of the 'S' extruder is slightly shorter, so the MMU2 profile was pushing through a little too much filament to the nozzle every time - not noticeable at the time, but that tiny bit extra builds up with every layer.
Hope you get your problem solved Frank.
Re: MMU 2 two color print - purge block with strings and blobs
Thanks Peter - Mine is the MMU2S - and my problem was entirely user error on my part. I spotted last night that I'd accidentally selected the wrong Slic3r profile (the MMU2 instead of MMU2S) - a couple of tests later and my blobbing problem is solved. I guess the problem was the design of the 'S' extruder is slightly shorter, so the MMU2 profile was pushing through a little too much filament to the nozzle every time - not noticeable at the time, but that tiny bit extra builds up with every layer.
Hope you get your problem solved Frank.
Yes, the "S" version has a shorter extruder which allows almost 8mm of additional print height (although I don't believe that has been implemented within firmware as yet). But feeding too much filament on load due to incorrect printer selection is one cause of this 🙁
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: MMU 2 two color print - purge block with strings and blobs
Hi Peter,
Thanks for your comment. I'm still waiting for my upgrade to S - meaning I still have the "non S" version and because of this I cannot choose the S printer version in Slic3r - as I also didn't upgrade Slic3r to S version.
I will have to repeat my print. Hope I will find the time for it soon
Best
Frank
Re: MMU 2 two color print - purge block with strings and blobs
Hi Peter,
Thanks for your comment. I'm still waiting for my upgrade to S - meaning I still have the "non S" version and because of this I cannot choose the S printer version in Slic3r - as I also didn't upgrade Slic3r to S version.
I will have to repeat my print. Hope I will find the time for it soon
Best
Frank
Frank, I think Simon's issue was a little different from yours and an easier solution. I don't print with PET and I don't have the issue you have, so I don't think I can assist further. Sorry 🙁
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: MMU 2 two color print - purge block with strings and blobs
I'm having the same problem too. These blobs eventually cause a layer shift when the nozzle hits them. The purge block on the right is 0.2mm layer height and the one on the left is 0.15mm. Why does it work at 0.15 and not 0.2??? Their setup is identical apart from the layer height
I hope you can see the pictures?
Re: MMU 2 two color print - purge block with strings and blobs
The 'blobby' purge block looks very similar to the ones I had when I was using the wrong profile (MMU2 instead of MMU2S). Have you checked you are using the correct printer profile in Slic3r?
Re: MMU 2 two color print - purge block with strings and blobs
I'm certain I am using the correct profile but I will check. The 0.15mm and 0.2mm would both be on the same profile though so why the difference?
Re: MMU 2 two color print - purge block with strings and blobs
To add to this, I print solely using PLA.
With my MMU2, I got bad blobs on the purge block which ended up causing crashes - either that or I had to sit with my mini-drill tool and chase it around as it was printing to remove the worst of the excess....
Since my upgrade to MMU2S, this problem has gone - it's the same STL (at 0.20) as before, re sliced after I reconfigured Slic3r. I wonder whether it's a hardware or a config change in Slic3r?
Whatever - I'm glad the problem has gone,
RE: MMU 2 two color print - purge block with strings and blobs
this problem was happening to me, and i found that the solution was under the printer settings tab, under "single extruder mmu set" there is a seeting called "extra loading distance". make sure that this is set to at least -25. i had set it to 0 like 0calvin had suggested in his video, but on the mmu2s that seems to cause blobs on the purge block