FLEX dead with MMU2s?  

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NealC
(@nealc)
Eminent Member

I wanted to do a 2 color print with FLEX. It seems to load to the nozzle but then it just comes out of the MMU2 area between the two PTFE tubes. Seems like FLEX is a NO GO with MMU2? How can you even use FLEX on a i3 MK3S with MMU2S even in single filament mode as it's not going to load it seems via the MMU2 path???

Neal C
Richmond, VA...
Posted : 31/05/2019 5:43 pm
gnat
 gnat
(@gnat)
Prominent Member

Do you have a pic of the result? I'm having a hard time picturing it. 

Are you sure it's really making it to the nozzle? Is it breaking and then coming out of the MMU? Is it pushing a loop (e.g. unbroken filament) out of the MMU?

MMU tips and troubleshooting...
Posted : 01/06/2019 3:27 pm
NealC
(@nealc)
Eminent Member
Posted by: gnat

Do you have a pic of the result? I'm having a hard time picturing it. 

Are you sure it's really making it to the nozzle? Is it breaking and then coming out of the MMU? Is it pushing a loop (e.g. unbroken filament) out of the MMU?

I'm not sure as the nozzle/extruder was not feeding but the MMU2 was pushing so the only place the filament had to go, being flexible, was out the MMU2 in the open path. I'll have to try again someday but I found it odd there are no print profiles for FLEX in PrusaSlicer 2.0 either.

Neal C
Richmond, VA...
Posted : 01/06/2019 4:28 pm
Brad
 brad
(@brad)
Eminent Member

Yes, that has been a concern of mine too.  One of the features that sold me on the MK2 a couple of years ago was the fact that it didn't have a Bowden extruder and could print flexible filament.  Since then I have added the MK3s and the MMU2s to our household and let my daughter have the MK2 when she moved out of state.

 

When the MMU2 first came out, it was touted that flexable filament printing was "coming soon" but I haven't heard of anyone getting flexible filament to work on an MMU2.  Love to know how if someone has it working.

 

  - Brad

 

...
Posted : 02/06/2019 2:24 am
toaf
 toaf
(@toaf)
Noble Member

it works. slow the volumetric down mine is at 5

 

and I have the loading/unloading speeds down abit too.

I have a Prusa,therefore I research....
Posted : 02/06/2019 2:54 am
dick.v
(@dick-v)
Eminent Member

Hi, I would say if you want to print with flex materials with the MMU2s first make sure that your MK3S/MMU2s is working perfect with eg. PLA or PETG.

As we all know by now this is a major challenge if almost not possible at all.....

Printing Flex is very challenging, you need a perfect working printer setup in the first place and master your skills regarding temperature, both nozzle and heated bed, etc. etc. and the type of filament and brand you want to use.

Soo my advice is: Forget printing Flex for the moment on the MK3s/MMU2s unless you have a perfect working printer capable of printing multi-color prints for more than >1000 hours without any issues!

This post was modified 1 year ago by dick.v
Posted : 02/06/2019 11:13 pm
hwlin85
(@hwlin85)
Eminent Member
Posted by: toaf

it works. slow the volumetric down mine is at 5

 

and I have the loading/unloading speeds down abit too.

Hi Toaf, 

Did you manage to slow the unloading speed in the multimaterial profile instead of a single extruder? 

I would love to know how you did that. 

I tried to slow the unloading speed in the slicer but i can only find the parameter for unloading for single extruder.

 

Posted : 14/08/2019 6:32 am
peter.l22
(@peter-l22)
Honorable Member
Posted by: Brad

When the MMU2 first came out, it was touted that flexable filament printing was "coming soon" but I haven't heard of anyone getting flexible filament to work on an MMU2.  Love to know how if someone has it working.

I've gotten a fairly hard (92A) TPU to work well. I created a new filament profile based on the "Generic PLA" profile but with the following changes:

  • Changed the max volumetric flow rate to 5
  • Set the filament type to "FLEX"

I have some softer flex filaments but haven't attempted them yet.

One thing to be careful about is that there's a lot of different types of flex filaments, and softer filaments are going to be harder to print. You may need to slow the print speed down even further.

Also, when you set the filament type to "FLEX," there's something that sets the print speed on the printer to something like 35%. So combining that with the volumetric flow rate of 5 mm^3/sec means that your print will be veeerrrry slooooooow. But the results I got were good, and even had minimal stringing.

Posted : 17/08/2019 6:45 pm
hwlin85
(@hwlin85)
Eminent Member

Just curious what is volumetric flow rate, I am always confuse about this term.

Posted : 17/08/2019 8:35 pm
peter.l22
(@peter-l22)
Honorable Member
Posted by: hwlin85

Just curious what is volumetric flow rate, I am always confuse about this term.

It's how fast the extruder pushes material through the nozzle, measured in cubic millimeters per second.

In the context of the filament settings, Slic3r will slow the print down to keep the print from trying to extrude material faster than the volumetric flow rate parameter.

Posted : 18/08/2019 12:21 am
hwlin85
(@hwlin85)
Eminent Member

If I change the volumetric flow does other setting will adjust with it?

Posted : 18/08/2019 12:49 am
peter.l22
(@peter-l22)
Honorable Member
Posted by: hwlin85

If I change the volumetric flow does other setting will adjust with it?

No. Volumetric flow is an independent setting. For any given movement, the slicer will use the slower of the linear speed (the mm/sec speeds) and the volumetric flow rate.

Posted : 18/08/2019 1:26 am
geki
 geki
(@geki)
Eminent Member

I did print with flex (single and PLA als the first 4 layers) as well, but the problem is not the printing itself, that works fine with the adjusted speeds. I have only problems with the loading/unloading sequence. It's way too fast for flex. Is there an option to change that or is it inside the MMU firmware?

Posted : 29/08/2019 3:29 pm
bret.h
(@bret-h)
New Member
Posted by: geki

I did print with flex (single and PLA als the first 4 layers) as well, but the problem is not the printing itself, that works fine with the adjusted speeds. I have only problems with the loading/unloading sequence. It's way too fast for flex. Is there an option to change that or is it inside the MMU firmware?

I too am having problems loading Ninjaflex. I found that under "Advanced" settings under the "filament settings" there are toolchange parameters that effect loading and unloading, but I'm not sure what to set them to. I looked for flex presets for a clue but can't find any presets. Anyone know if there are any flex presets somewhere that could at least give me a starting place?

...
Posted : 01/09/2019 6:03 pm
geki
 geki
(@geki)
Eminent Member

There are presets for flex if you are in the "Filament Settings" and click the green flag next to the filament selection box. It turns red and you see all filaments also the flex.

Changing these options didn't help because the problem is how fast the extruder gears are spinning, while the filament is pushed through the loading tube. And that seems to be controlled by the MMU trough the T-command.

They are either to fast to catch it (so loading fails) or once they got it (or after I helped) they are pushing the filament so fast that it tangles around the gears since it's too flexible to build up the necessary force needed for going through the heat block.

 

Posted : 04/09/2019 1:36 pm
geki
 geki
(@geki)
Eminent Member

Just did another test. Even with loading speeds of 1mm/s it doesn't change anything. I wonder what it is for then...

If the gears would be much slower (MMU and extruder) it would work just fine, since I have tried it manually.

The start sequence for cleaning the nozzle is at least easy to edit because also this one is way too fast for flex.

This post was modified 1 year ago by geki
Posted : 04/09/2019 2:01 pm
martijn.gevaert
(@martijn-gevaert)
New Member

Any update on this functionality?

I'm considering purchasing the MMU2s with the purpose of using it for prints that contain both flexible and hard parts, such as a print in place RC-wheel with wheelhub.

Without this functionality it's not worth the money for me personally.

Could this functionality be part of a possible MMU3? Will it ever come to the MMU2S?

Posted : 22/07/2020 12:44 am
Yveske
(@yveske)
Trusted Member

This works for me: https://www.prusaprinters.org/prints/12586-ninjaflex-profile-zero-stringing-flawless-print-be
You will need to change the allowed printer types to include MMU or take the settings from the included .3mf

It did my very first multi-colour print directly in NinjaFlex (but had printed several single colour NinjaFlex prints beforehand)
Just don't forget to loosen the screw at the extruder almost completely (and reset for other filament afterwards !!!).
I didn't need to change the MMU, I use the same settings for both PLA, PETG and NinjaFlex.
The screws of the MMU are about 1 mm from the top.
I do have problems with the NinjaFlex taking an alternative route if it is not set quite right though.

Greetings,
Yveske

Having problems with bed adhesion every morning......
Posted : 22/07/2020 9:40 am
hwlin85
(@hwlin85)
Eminent Member
Posted by: @yveske

This works for me: https://www.prusaprinters.org/prints/12586-ninjaflex-profile-zero-stringing-flawless-print-be
You will need to change the allowed printer types to include MMU or take the settings from the included .3mf

It did my very first multi-colour print directly in NinjaFlex (but had printed several single colour NinjaFlex prints beforehand)
Just don't forget to loosen the screw at the extruder almost completely (and reset for other filament afterwards !!!).
I didn't need to change the MMU, I use the same settings for both PLA, PETG and NinjaFlex.
The screws of the MMU are about 1 mm from the top.
I do have problems with the NinjaFlex taking an alternative route if it is not set quite right though.

Greetings,
Yveske

Hi Yveske

Did you use 0.4 nozzle or 0.6 nozzle on your MMU when you print with NinjaFlex? 

Did you use the softest ninja flex with this profile like the 85A very stretchy ?

I checked out the profile it uses 7.5mm volumetric speed it is a bit high no? 

I am curious did you mod your MMU in any way? 

Looking forward to your reply.
Henry

Posted : 22/07/2020 10:21 am
Yveske
(@yveske)
Trusted Member

I'm using the standard 0.4 nozzle and haven't examined the profile, but I should because it is still stringy so I have to do a 'lot' of cleanup.

I have this NinjaFlex filament (+ the Flame, Sun and Midnight)
- https://www.123-3d.nl/NinjaTek-NinjaFlex-TPU-Snow-1-75-mm-1-kg-flexibel-3DNF0017510-i3689-t12188.html

I've first used the mods provided by jfromel
- https://www.prusaprinters.org/prints/19211-mmu2s-building-a-better-base
- https://www.prusaprinters.org/prints/16736-mmu2s-dual-blade-holder
- https://www.prusaprinters.org/prints/19738-mmu2s-idler-body-for-the-new-base
But I modified the 2 bases to do away with the brass inserts because I couldn't get hold of them due to corona.
I also modified the blade holder to add extra screws to hold the blades more firmly.
I didn't use the idler (separate download), because I couldn't dismantle the Prusa one and couldn't get spare rods.

I later added a mod of my own because I couldn't load PLA with the Prusa one (haven't tested the Prusa one with NinjaFlex)
- https://www.prusaprinters.org/prints/30254-mmu2s-holder-extended

I don't know if my own mod would have been enough because I didn't return the rest to stock... if it works, it works...

Let me know if you need anything else
Yveske

Having problems with bed adhesion every morning......
Posted : 22/07/2020 10:53 am
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