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Buying a new MK3 and the MMU 2.0  

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3dweltan
(@3dweltan)
Active Member
Buying a new MK3 and the MMU 2.0

I own an mk2s and an Mk3 (both work flawlessly). I want to get the MMU 2.0 but have no desire to tear apart my wonderful printers, so I am opting to get an Mk3 dedicated to the MMU 2.0. What is driving me nuts is the inconsistent responses from online CS at Prusa when I ask this simple question, "If I purchase a New MK3, it is MMU 2.0 ready ?". Other than the filament sensor that has the thread for the PTFE push fitting, what else has to be modified if I buy a BRAND SPANKING NEW Mk3 today !!
I have had many inconsistent responses. The instructions are very vague. This morning I was told I would have to replace the PTFE tube in the hotend plus the sensor cover ? If this is so, why wouldnt they just ship a brand new MK3 with it MMU ready ???
It is a pain in the ass to have to build a printer, get it working, then tear it apart again....

So, can one of my kindred tinkerer spirits please confirm what I would need to do if I purchase a NEW mk3 plus a new MMU, other than the filament sensor cover ?

Cheers from Snowy Atlanta, GA, USA

Posted : 28/01/2019 3:46 pm
JoanTabb
(@joantabb)
Moderator
Re: Buying a new MK3 and the MMU 2.0

Hi 3dWalten,
i suggest you order one or two extra mmu extruder PTFE Tubes, with your new mk3 order so that you have it available before you start assembling the kit!,
I also suggest you get some heatsink paste, and 5metres of 2.5x4mm ptfe.and,
I suggest that you buy a 4mm x 10mm pass through pneumatic fitting, for the top of your extruder housing

using your other printer, print a modified extruder top cap, with a 10mm thread, and pass through hole for the PTFE 'reverse bowden' tube

when assembling the extruder assembly, you should already have B7 parts for the Dyson style extruder housing, in the kit, and
you should have an extruder assembly, nozzle, heatblock, heater, thermistor, heatbreak, heatsink, pre installed PTFE and little black retaining clip,

before assembly, unscrew the heatsink off the heatbreak, the ptfe tube should remain with the heatsink, held in place by the black retainer.

put the hot end down, and keep hold of the heat sink. there should be a short length of ptfe sticking out of the top of the heatsink.

the easiest way to remove this, it to push it further into the heatsink and pull it out from the end that the heatbreak normally screws into...

the more difficult way to take it out, is to simultaneously push the black retaining ring into the heatsink and pull the PTFE out...

the almost impossible way is to tug on the end of the ptfe, with pliers or similar... just... don't try this approach

when reassembling the extruder it is MY PREFERENCE, to put a smear of heat sink paste, on the heatbreak threads, and screw the heatsink into place, then unscrew the heatsink half a turn, and insert the new PTFE tube, from the MMU kit, fully through the black ring, into the heatsink/heatbreak, pressing in firmly, and pulling the black ring away from the heatsink, then finally tightening the heatsink firmly against the heatbreak, this should result in the PTFE Being firmly trapped in the extruder

now complete the assembly of the extruder as per the mk3 build plan, with the exception of the extruder top cap...we can fit that later...

now complete the assembly of your new mk3

when you get round to fitting the einsy case lid, have a look at the MMU fitting instructions and clip off the appropriate corner to make space for the MMU cables, later...

completr the mk3 asembly.

assemble the MMU, making sure that all filament paths are clear, and run smoothly...

when it's time to install the orange ptfe tube between the MMU selector and the top of the extruder, reach for the 2.5x4mm tubing that you bought earlier, measure a length about 20mm longer than the orange tube, cut the ends perpendicular to the bore, and chamfer the inside of the ends of the new tube...put the orange tube back in the box, and install the new tube.

when it's time to install the filament feed tubes, measure 5 new 2.5mmx4mm ptfe tubes, to use and put the prusa tubes back in the box...

complete the assembly of the MMU, clip it on the top frame of the mk3, the wiring should go through the cutout in the einsy case that you made earlier,
now take the 4mmx10mm passthrough pneumatic fitting, and the new matching extruder top cap, screw together. install, without the tiny length of PTFE filament under it then insert the 2.5x4mm tube from the mmu selector, through the pass through connector to fill the space normally occupied by the tiny ptfe tube above the filament sensor...

assemble the reel holders and the filament arms etc., making sure that all of the filament paths are open and allow smooth passage of the filament.

and take your first test flight...

enjoy,

Joan

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 : 28/01/2019 5:09 pm
3dweltan
(@3dweltan)
Active Member
Topic starter answered:
Re: Buying a new MK3 and the MMU 2.0

I truly appreciate the in depth response (good info for later). Again though its just a simple question, If I buy a brand spanking new MK3, it is MMU 2.0 ready ? (other than the filament sensor cover with the threaded insert for the bowden fitting ? The new Mk3 kit has the correct PTFE tube for the MMU installed ?

Cheers from the about to be paralyzed state of GA (US - We dont do snow !)

3dweltan

Posted : 28/01/2019 5:55 pm
Peter L
(@peter-l)
Honorable Member
Re: Buying a new MK3 and the MMU 2.0


If I buy a brand spanking new MK3, it is MMU 2.0 ready ?

No. Nor can you get the MMU2 preassembled. You must perform surgery on your printer to replace the PTFE tube in the heatsink.

The new Mk3 kit has the correct PTFE tube for the MMU installed ?

No. You must perform surgery on your printer to replace the PTFE tube in the heatsink.

Cheers from the about to be paralyzed state of GA (US - We dont do snow !)

It's supposed to be -30F in Minneapolis Wednesday morning. Want to trade?

I don't know why Prusa doesn't just ship all MK3's with the right PTFE for the MMU2. It would certainly avoid a lot of confusion, and the MK3 runs just fine with the MMU PTFE as a single-filament printer. The difference is that the MMU2 PTFE has a smaller inner diameter so as to make thinner tips when the filament unloads.

But the simple fact is that the MMU2 is only sold as a kit, and Prusa expects you to be able to disassemble your hot end in order to install it. Maybe they're using this as a filter to weed out people who might be interested in the MMU2 but aren't prepared for the level of tinkering it takes to make it work consistently.

So maybe you should consider replacing the PTFE as a test you have to pass to qualify for owning an MMU2. As qualifying exams go, it's not too bad.

Posted : 28/01/2019 10:25 pm
3dweltan
(@3dweltan)
Active Member
Topic starter answered:
Re: Buying a new MK3 and the MMU 2.0

Brother I hate to disagree with you, and this why Prusa is shooting themselves in the old foot. I asked their CS multiple times and got the answer you gave me, but then I emailed Shane today and I got the following response (hope he doesnt mind me pasting his answer);

"Hello
Well all printers now carry the same PTFE tube, so as you said it would be the filament sensor cover that would need to be changed physically and the new firmware covers the MMU2, so it would detect and work with it, so only thing would be to build the MMU2 unit, update the firmware, calibrate it and you should be all set to go.

Thank you :)"

So, simple answer according the Shane is that it does have the correct ptfe tube for the MMU installed ready for the MMU.

Im with you, I dont get why they wouldnt promote the fact that the new Mk3 is mmu ready (minus the sensor cover and firmware) !!

PS: Ive built 33 printers in the last 6 years, so I dont care about the build, BUT it sucks to build a beautiful MK3, calibrate it, print then 5 mins later take it apart.... IMHO and 1 inch of snow in GA closes the entire state. Thats why the film the walking dead 20 miles from my house 😀

Posted : 28/01/2019 11:02 pm
Peter L
(@peter-l)
Honorable Member
Re: Buying a new MK3 and the MMU 2.0


"Hello
Well all printers now carry the same PTFE tube, so as you said it would be the filament sensor cover that would need to be changed physically and the new firmware covers the MMU2, so it would detect and work with it, so only thing would be to build the MMU2 unit, update the firmware, calibrate it and you should be all set to go.

Thank you :)"

It looks like you are correct, and the new MK3s are shipping with MMU compatible PTFE tubes, per the assembly instructions. Look for a green dot on the heat block: if you have a green dot, then you're good to go.

That will teach me to speak from experience and not RTFM 🙂

Posted : 29/01/2019 4:01 am
3dweltan
(@3dweltan)
Active Member
Topic starter answered:
Re: Buying a new MK3 and the MMU 2.0

I think this post should be Tagged by the mods !

This is important. Its a selling point and worth noting. I love my various Prusa's and frankly had no desire to tear them apart for the MMU. Fortunately I have the means to dedicate a new Mk3 to the MMU. The idea of tearing apart a newly built printer for the MMU may have been off putting for some people, so this is great news for anyone who thought twice !!

Now, as I pull the trigger on this, Prusa will announce an MK4 with integrated MMU 😀

Posted : 29/01/2019 3:37 pm
JuanCholo
(@juancholo)
Reputable Member
Re: Buying a new MK3 and the MMU 2.0

the reason the PTFE tube in the extruder was changed was due to the redesign of the extruder body which has gone through 3 major revisions (R3 current one) because the older design was having issues with heat creep, and some relation to the 602 wavy extrusion issue. many people with MK3s have the older R1 or R2 designed extruder, so when starting a MK3 conversion you first need to change the extruder from the older design and thus the PTFE tube in the extruder must also be swapped out during the first stage of the rebuild to mmu2.

the additional alteration in using the PTFE tube is since the filament sensor is currently not used with the prusa firmware and it can cause problems is to by pass it and replace the original orange MMU2 PTFE tube with a longer one that goes fully down right into the bontech gears. this eliminates a problem point where the filament can get stuck right after the orange tube ends the filament raw and unsupported passes the filament sensor then enters a tapper to get to the bontech gears. the stepped walls from 3d printing the tapper down into the bontech can catch the filamant tip and prevent it from hitting the gears leading to a layer skip. the movement of the machine can self correct the hung filament but the damage is done and a area or layer has been skipped leading to a failure. by ramming the filament totally into the bontech gears can a possible issue be avoided. this requires a different filament sensor cap on the extruder body, also some other minor changes.

so getting back the green dot on new extruders signifies that the correct PTFE tube is installed to work with the R3 extruder body.

the first steps in the latest MMU2 build manual is to first retrofit your MK3 model if it did not come with a R3 extruder to the newest version make sure the printer is 100% functional then start the MMU2 conversion. if you just bought the MK3 then it should have the R3 already.

“One does not simply use a picture as signature on Prusa forums”

Posted : 29/01/2019 5:38 pm
3dweltan
(@3dweltan)
Active Member
Topic starter answered:
Re: Buying a new MK3 and the MMU 2.0

All good information which I was aware of, but my original question was pretty simple, does a current MK3 need any mods beyond the filament sensor/ firmware. The good news is NO.

Posted : 29/01/2019 5:51 pm
JuanCholo
(@juancholo)
Reputable Member
Re: Buying a new MK3 and the MMU 2.0

yes it does but it depends on your level of tolerance for what it outputs. also depends on how new your mk3 is as there are rolling production changes.

as for the MMU2 right off the bat, you will need to download the Pmeyers Spools and assemble those using the prusa parts to create a spool holder that actaully works. the parts will take a long time to 3d print and you can only fit the parts for 2 spools at a time. total print time is like 5 hours for 2 spool conversions.

there are 3rd party Selector bodies that are superior to the prusa design as well.

as for the MK3 well there are numerous fixes for the machine on thingiverse to address problems with it to make it better.
again depends on if you are happy with your mk3 as it currently is configured.

“One does not simply use a picture as signature on Prusa forums”

Posted : 29/01/2019 5:57 pm
3dweltan
(@3dweltan)
Active Member
Topic starter answered:
Re: Buying a new MK3 and the MMU 2.0

Im still not 100% convinced the mmu 2.0 is ready for prime time based on talking with people who have it, but then again what is with additive printing ? My palette 2 pro is great but it too is not 100% ready. Like most of this technology the thermoplyae pass (think spartans) is not so much the equipment but the human variable. I have been color merging for a few years with a geetech hotend and it works great, but Its only as good as the moron feeding the data in ! 😀

Posted : 29/01/2019 6:58 pm
brian.k23
(@brian-k23)
New Member
Re: Buying a new MK3 and the MMU 2.0

Hold off on that purchase. The MMU is getting upgraded to MMU 2.5 because the MMU 2 is almost unworkable.

So just hold off a few weeks and wait for the smoke to clear. You don't want the 2.0 and hopefully the 2.5 fixes most of the issues people have been having. Read through some forum posts, this is a big issue and you don't want to throw $300 out the window and then wait months for the new upgrade to show up.

Posted : 15/02/2019 9:13 pm
Peter L
(@peter-l)
Honorable Member
Re: Buying a new MK3 and the MMU 2.0


Hold off on that purchase. The MMU is getting upgraded to MMU 2.5 because the MMU 2 is almost unworkable.

So just hold off a few weeks and wait for the smoke to clear. You don't want the 2.0 and hopefully the 2.5 fixes most of the issues people have been having. Read through some forum posts, this is a big issue and you don't want to throw $300 out the window and then wait months for the new upgrade to show up.

According to Prusa, all MMU2 shipments are going out as the MMU2S. So if you order today you will get the upgraded version, no need to wait for a separate upgrade.

Posted : 18/02/2019 11:05 pm
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