TPU on MMU3  

RE: TPU on MMU3

Hi Philip - 

I haven't printed with it myself, but I think you can create a TPU filament entry by adding a new filament, edit all the paramters, and selecting the type "FLEX" in the advanced section of the Filament Settings. 

Thomas

RE: TPU on MMU3

I've done that. But I don't understand the reason why. There are more materials they are not supported. And you have to create every single one. And it could be so easy. 

RE: TPU on MMU3

I have turned off the MMU in the settings menu and then just fed the TPU directly into the extruder using the standard (non-MMU3) profile.

RE: TPU on MMU3

Thank you! But that's not what I want. I want to mix different materials TPU included. 

I printed a rim with the tire around in one step. The rim is PETG and the tire TPU. 

RE: TPU on MMU3

I created a TPU profile for the MK4 / MMU3 (copy all data from a MK3 profile). I had to change the filament sensor back to the original solution (spring loaded ball) because the soft TPU did not move the lever enough to trigger the sensor.
I was able to print a PLA / TPU mix. It was not reliable Unloading of the TPU creates sometimes mess in the nextruder, which could be caused by the ramming sequence. Also the extrusion volume is not good enough which might created by the tension of the TPU caused by the MMU and the long tubes.
Needs definitely more optimization - but right now I do have other priorities.

RE: TPU on MMU3

Posted by: @zwirbel

I have turned off the MMU in the settings menu and then just fed the TPU directly into the extruder using the standard (non-MMU3) profile.

I assume you are leaving the MMU3 mounted? If so, how are you placing the TPU filament spool to enable a direct feed to the extruder?

Thank you! But that's not what I want. I want to mix different materials TPU included.

I printed a rim with the tire around in one step. The rim is PETG and the tire TPU.

Due to the push-pull process of loading filament flexible materials are problematic, I assume this is why they are not officially supported for the MMUs.

Whilst it *has* been done, regard it as no more than a party trick.  For practical purposes TPU and hard filaments cannot easily be printed together with any of the MMUs.

Luckily the QL does this well so there is a way - just not with any Mk3/4 + MMU2/3 combination.

Cheerio,

RE: TPU on MMU3

Hey guys,

I wanted to add my experience here before opening a separate Issue with Prusa, as this might be relevant for you as well:

Did any of you experience the issue, that the new Nextruder Filament Sensor Assembly on Mk4 with MMU3 does not recognize flexible filament?

Apparently it jus doesn't trigger the sensor, because it does not have enough tension to sufficiently move the idler to the side, which is what the new sensor detects. I tried recalibrating it, but calibration fails, as the idler is not moving enough and the printer doesn't detect filament.

RE: TPU on MMU3

Posted by: @ralf711

Did any of you experience the issue, that the new Nextruder Filament Sensor Assembly on Mk4 with MMU3 does not recognize flexible filament?

I did and I came to the same conclusion. But my MMU can't push flexibles all the way into the extruder anyway, so it doesn't really matter.

RE: TPU on MMU3

I recently received my MMU3 for the MK4 but haven't installed it yet so excuse me if this is a stupid question.  I hear a lot about bypassing the MMU when feeding TPU.  Besides disabling it in the setting screen, are you disconnecting the Bowden tube above the filament sensor or some other way.  I want to still be able to use TPU after I get the MMU3 installed, so just looking for ideas.

Thank you.

RE:

My setup has the MMU unit still centered and I have a Mk4 spool holder and filament guide to one side. I have a magnetic release PTFE connector in the tube between the MMU and Nextruder which allows a direct feed from the top spool holder without the need to remove the PTFE tube from the Festo fittings.  Here's what I used:

https://www.printables.com/model/581332-spool-holder-for-original-prusa-mk4

https://www.printables.com/model/30599-filament-guide

https://www.printables.com/model/873440-magneticslotted-ptfe-rotating-disconnect

It works well. 

RE: TPU on MMU3

To ensure you: yes, you will still be able to print TPU no problem, you just have to de-activate the filament sensor. Otherwise when loading, it feeds and feeds and feeds because it doesn't detect the filament, until it is all tangled up in the main gear, at least that is what happend to me.

Dsconnect the hose as described and feed straight to the Nextruder. I myself do not even use a double coupling, I just release the tube from the coupling at the nextruder and feed straight through it.

The only thing that changes is, that loading doesn't auto start with the sensor deactivated.

RE: TPU on MMU3

I do not agree! You just loose the screws on the nextruder a bit, and the sensor works just fine. 

An you can go through the MMU also. 

RE: TPU on MMU3

It appears to be working
- at least with somewhat hard Overture TPU (A95, I think)

I'm not gonna call it "reliable" - not yet, anyway:
Still barely 200 changes through the MMU3 on MK4, but I expected to run into some kind of issues.
But so far, it has been a very smooth experience.

Made no hardware changes - not even loosened the screws on the nextruder (they weren't that tight to start with).
Based on the generic FLEX profile, I've slowed down printing and load/unload speeds (1,5/20/70) and increased purging amounts.

(I print in enclosure, directly from drybox, onto unheated PEI with glue stick)

RE: TPU on MMU3

I too have attempted to print mixed material of PLA and TPU.  I was noticing some TPU buildup on the wipe tower that the nozzle started hitting when purging the PLA.  I paused the print and trimmed the bulges.  After resuming and watching the nozzle temps, it appears that the nozzle temp drops down to the TPU temp setting when trying to purge the leftover PLA.  I would have expected that the slicer/firmware would have used the PLA material temp during this phase of the purge tower.

I kept the print running but finally had a TPU feed error about half way through (TPU wound around extruder wheel).

I talked with Prusa and they said its a known thing, suggested that there may be an unofficial workaround, but would not offer what it is.

Therefore, I am asking you experts what can I do as a workaround until the Prusa slicer properly handles material differences?  Is there some custom GCODE that can fix this (without having to manually manipulate the sliced file)?

TIA

RE: TPU on MMU3

Do you suppose we will get true multimaterial capabilities in the next slicer release?

RE: TPU on MMU3

I have, for the last few days, been testing some multi-material prints (TPU and PLA), nothing incredibly complex, mostly just some basic shapes with TPU at the center, or coasters with some 'anti-slip' tpu on top.

My MK4S with MMU3 has been able to handle that with absolutely no problem, we are talking about up to 50 filament changes sometimes and I have had no issue whatsoever alternating between PLA and TPU.

I did have to create a custom profile for the flex material (basically copied the flex default from the mk4s w/o MMU3), and I have only tested this with 95A t hardness TPU, but it has worked with no issue. Find the code below to import to the printer, but again, it has close to no mod from the default flex one.

[filament:Prusament FLEX @MK4S MMU3]
bed_temperature = 60
bridge_fan_speed = 70
chamber_minimal_temperature = 0
chamber_temperature = 0
compatible_printers = 
compatible_printers_condition = printer_model=~/(MK4S|MK4SMMU3|MK3.9S|MK3.9SMMU3)/ and nozzle_diameter[0]!=0.8 and nozzle_diameter[0]!=0.6 and printer_notes!~/.*HF_NOZZLE.*/
compatible_prints = 
compatible_prints_condition = 
cooling = 0
disable_fan_first_layers = 1
enable_dynamic_fan_speeds = 0
end_filament_gcode = "; Filament-specific end gcode"
extrusion_multiplier = 1.1
fan_always_on = 0
fan_below_layer_time = 17
filament_colour = #FF8000
filament_cooling_final_speed = 3.4
filament_cooling_initial_speed = 2.2
filament_cooling_moves = 4
filament_cost = 39.98
filament_density = 1.19
filament_deretract_speed = 20
filament_diameter = 1.75
filament_infill_max_crossing_speed = 0
filament_infill_max_speed = 0
filament_load_time = 0
filament_loading_speed = 28
filament_loading_speed_start = 3
filament_max_volumetric_speed = 4
filament_minimal_purge_on_wipe_tower = 15
filament_multitool_ramming = 0
filament_multitool_ramming_flow = 10
filament_multitool_ramming_volume = 10
filament_notes = "Affordable filament for everyday printing in premium quality manufactured in-house by Josef Prusa"
filament_purge_multiplier = 100%
filament_ramming_parameters = "250 100 40.1613 40.3548 40.4516 40.3548 40.2581| 0.05 40.1483 0.45 40.3419 0.95 40.3419 1.45 40.3419 1.95 40.3419 2.45 40.3419 2.95 40.3419 3.45 40.3419 3.95 40.3419 4.45 40.3419 4.95 40.3419"
filament_retract_before_travel = 2
filament_retract_before_wipe = nil
filament_retract_layer_change = nil
filament_retract_length = 2.5
filament_retract_length_toolchange = nil
filament_retract_lift = 0
filament_retract_lift_above = nil
filament_retract_lift_below = nil
filament_retract_restart_extra = nil
filament_retract_restart_extra_toolchange = nil
filament_retract_speed = 60
filament_settings_id = ""
filament_shrinkage_compensation_xy = 0%
filament_shrinkage_compensation_z = 0%
filament_soluble = 0
filament_spool_weight = 230
filament_stamping_distance = 0
filament_stamping_loading_speed = 20
filament_toolchange_delay = 0
filament_travel_lift_before_obstacle = nil
filament_travel_max_lift = 0.6
filament_travel_ramping_lift = nil
filament_travel_slope = nil
filament_type = FLEX
filament_unload_time = 0
filament_unloading_speed = 90
filament_unloading_speed_start = 100
filament_vendor = Prusa Polymers
filament_wipe = nil
first_layer_bed_temperature = 60
first_layer_temperature = 235
full_fan_speed_layer = 3
idle_temperature = 70
inherits = Prusament PLA @MK4S
max_fan_speed = 100
min_fan_speed = 70
min_print_speed = 20
overhang_fan_speed_0 = 0
overhang_fan_speed_1 = 0
overhang_fan_speed_2 = 0
overhang_fan_speed_3 = 0
slowdown_below_layer_time = 6
start_filament_gcode = "M900 K{if nozzle_diameter[filament_extruder_id]==0.4}0.05{elsif nozzle_diameter[filament_extruder_id]==0.25}0.14{elsif nozzle_diameter[filament_extruder_id]==0.3}0.07{elsif nozzle_diameter[filament_extruder_id]==0.35}0.06{elsif nozzle_diameter[filament_extruder_id]==0.6}0.03{elsif nozzle_diameter[filament_extruder_id]==0.5}0.035{elsif nozzle_diameter[filament_extruder_id]==0.8}0.015{else}0{endif} ; Filament gcode\n\n{if printer_notes=~/.*(MK4IS|XLIS|MK4S|MK3.9S).*/}\nM572 S{if nozzle_diameter[filament_extruder_id]==0.4}0.036{elsif nozzle_diameter[filament_extruder_id]==0.5}0.025{elsif nozzle_diameter[filament_extruder_id]==0.6}0.02{elsif nozzle_diameter[filament_extruder_id]==0.8}0.014{elsif nozzle_diameter[filament_extruder_id]==0.25}0.12{elsif nozzle_diameter[filament_extruder_id]==0.3}0.08{else}0{endif} ; Filament gcode\n{endif}\n\nM142 S36 ; set heatbreak target temp"
temperature = 235