I Need Help With Multi Material Printing

I have finished building my 2 multi material rigs. One with a MMU2S and one with a Diamond Hot end. I have both printers working. The red printer with the MMU2S I have had printing without the MMU2S connected and calibrated it pretty well before connecting the MMU2S and adjusting the settings in marlin 2.0.5.3 for it. The black printer with the diamond hotend I have printing with whatever first color I use. I am all setup and ready to figure this out. Here is my current workbench configuration.. https://imagizer.imageshack.com/v2/xq90/923/Iuvgri.jpg

I have heaters pid autotuned, end stops calibrated, printer configurations all setup in both S3D and PrusaSlicer although I am pretty sure I am missing from the start gcode on both. I have built and wired these machines well. I know the right youtube tutorials to follow now to tune for speed and salmon skin and other quality issues. If I can just get past these few issues with either the slicer or marlin I know these machines will impress. I am pretty sure I am closer on the diamond hotend. Currently it will start a print with the first nozzle but when it switches to the second filament the printer just freezes. I have to cycle the power or push the reset button. This printer has marlin 2.0.5.3 and I have enabled 3 extruders and single nozzle and everything has compiled and with PrusaSlicer I have 3 extruders set and even set the correct color to each filament in the slicer. I found some start Gcode that included leaving a blob of each color filament as a prime just before the print starts. When i apply this Gcode to Prusa slicer it behaves correctly and I get 3 blobs. There was no purging action so the blobs aren't exactly all the right color but there is no mistaking that all 3 extruders function correctly here. Just when I start printing that multi colored gecko after the first color, at the moment it is supposed to start using the second extruder the printer just freezes. I have tried re loading and reslicing the file and any settings that i am playing with aren't getting me any results. Anybody out there have any ideas what might be my problem with the Diamond hotend rig?

Couple of things I check:
- open the gcode file and see if there's commands that don't belong there. A pause maybe (M600) or emergency stop (M112) or something else...
- connect to the printer usb and see if there's errors printed. Also at least in Octoprint, the commands sent to the printer can be seen in the console log so that helps tracking down the problem

You know I have never actually opened a sliced file to look at the gcode before. Terrible ain't it? Well I looked at a few different single filament gcode files as well and it is not hard to understand at all. But i do not understand what switching to another extruder should look like. This is the diamond hotend. It needs no retraction or anything just to start using a different stepper for E. I opened the sliced 3 color lizzard and scrolled down to where the first 'toolchange' should happen and i believe this is the exact point my machine chokes. But i do not know if it is good or what using e1 now instead of e0 would look like as gcode. Here is where the gcode changes filaments for the first time and where my machine hangs not like the print stopped but I have to cycle power to regain control of the printer. It freezes.
https://imagizer.imageshack.com/v2/xq90/924/eEtfds.png

This is the start of that sliced lizzard file..
https://imagizer.imageshack.com/v2/xq90/922/DGEFJE.png

I installed Repetier Host and downloaded a different multi material test print and sliced it with Cura and printed it from USB and it did the exact same thing at the switchover to the second filament. I took this screenshot..
https://imagizer.imageshack.com/v2/xq90/923/XlWSX3.png

I also posted up these screenshots with a quick description of my problem in the 3d printing multimaterial facebook group and someone posted this up. Spegelius does this make sense to you? I think i know where he is saying to put it but i do not understand a lick of it. Is this right or gonna hurt me?
https://imagizer.imageshack.com/v2/xq90/922/yGbsbl.png

Yep, gcode is actually quite straightforward once you take the plunge. As these machines aren't very intelligent, gcode is just a list of commands for the printer to execute, most of them movement in X, Y, Z and E.

The command that changes the active extruder is T. So T0 is E0, T1 is E1 and so on. https://reprap.org/wiki/G-code#T:_Select_Tool. Extruder == tool in this case. That's all there is to it. What actually happens depends on our hw, but in simplest case Marlin basically starts driving E1 stepper drive instead of E0 (if T1 is issued). With mixing, Marlin runs all the extruders defined by the mixing ratios.

The M163 commands suggested are probably required, it might be that Marlin doesn't define default mixing ratios for the extruders so when executing T0, T1 etc, it crashes because it doesn't know what to do. So add those M163 commands to start gcode or run them before starting a print (not sure if the settings are stored to EEPROM so they might be reset when the board is reset). Can't remember how it was when I was messing with it...
Those M163 commands in the list are the per-extruder all-in settings, i.e. T0 drives only E0, T1 drives only E1...

That last bit seems to be more of an nice-to have feature, not required to get tool changing going. But it seems that with that you'll get an extra menu item where you can change material during printing and do load and unload.

So I am suspecting I have something wrong in my firmware even though it compiles and the printer otherwise works. I installed repetier and used cura as the slicer and downloaded a completely different test print and even printed from USB instead of SD and got the exact same results. So in configuration.h I have single nozzle enabled but have left mixing extruder out for now. From what i read the mixing extruder was just to enable the m163 and m164 commands for mixing ratios and running multiple extruders simultaneously. While i do want to get to that for now i am just trying to use 1 at a time and thought this was ok. I will try enabling this and see what i get. I am also unsure if i need to do anything to link or multiplex the one temp and or heater for the 3 extruders or if all of that is done with just enabling the single nozzle. I am really at a loss for where my problem is at the moment. At the start of the print I do get all 3 extruders to prime? I don't even know if this is in my slicer gcode or firmware. Why can't there just be a youtube tutorial / walkthrough for setting up the Diamond Hotend with a 32 bit controller and marlin 2.0.5.3? If I can get this figured out I swear I will pay it forward and make one. Enough complaining. Back to the debugging...

Breakthrough! Thank You Spegelius. So marlin wouldn't compile with mixing extruder and single nozzle and marlin wouldnt compile with mixing extruder and anything greater than 1 extruder selected. SO the only way to configure for the diamond hotend is to have just 1 extruder and leave single nozzle commented out and uncomment mixing extruder and have 3 steppers selected. And I am switching filaments. Been working out some final start gcode gremlins(don't want any retractions or filament unloads at changes) and I think I will get my first Multi Material Print this evening.
https://www.youtube.com/watch?v=hGpCFCEIuXI

Ok now we gotta get the MMU2S up and going. I entered the menu on the mmu itself and adjusted the length for the ptfe tube from the mmu to the extruder. I was however lost on how to adjust for the distance between the driven gear of the extruder and the nozzle. I mean i know where that is, I just do not understand what the numbers are or what they adjust. And sadly i have found no real answer. The youtube video i watched on setting this up skipped over this leaving it alone because his extruder was a near identical match to the prusa mk3 or mk3s extruder. These numbers, what do the individual numbers here mean? For filament load and ramming..
https://imagizer.imageshack.com/v2/xq90/923/MmFZt8.png

By following a tutorial on youtube i got as far as trying to start a print but got weird behavior out of the extruder gear and putting it in relative mode made no difference. I made this short video of what it was doing on the initial prime line at the start of a print. https://www.youtube.com/watch?v=iICQ8sENQJs&t= . That prime line is in the start gcode. I just need known good start/toolchange/end gcode for the MMU2S and to get this distance from the gear to the nozzle set right and i will be printing big stuff in color and with stunning precision.

I guess the number are the lengths and speeds, the loading and ramming have been split into smaller moves.

I'll have a look at Marlin after work, I wonder if the current code expects the filament sensor to be present. That's how it works on actual Prusa, but Prusa has it's own Marlin fork running and I think that shouldn't be a requirement on other printers as most don't have a filament sensor on the extruder...
The filament sensor functionality is neat, though. Now it actually detects when the filament has reached the extruder gears instead of relying on preset feed length. There was actually a smaal extruder upgrade needed, the idler and IR-sensor housing needed to be changed. There was a mention on the handbook that the special menu feed length tuning is not needed anymore due to this.

Ok had a look at configuration_adv.h and it seems that by default Marlin doesn have the sensor functionality enabled:

Code:

---

  //#define PRUSA_MMU2_S_MODE
  #if ENABLED(PRUSA_MMU2_S_MODE)
    #define MMU2_C0_RETRY  5            // Number of retries (total time = timeout*retries)

    #define MMU2_CAN_LOAD_FEEDRATE 800    // (mm/min)
    #define MMU2_CAN_LOAD_SEQUENCE \
      {  0.1, MMU2_CAN_LOAD_FEEDRATE }, \
      {  60.0, MMU2_CAN_LOAD_FEEDRATE }, \
      { -52.0, MMU2_CAN_LOAD_FEEDRATE }

    #define MMU2_CAN_LOAD_RETRACT  6.0  // (mm) Keep under the distance between Load Sequence values
    #define MMU2_CAN_LOAD_DEVIATION 0.8  // (mm) Acceptable deviation

    #define MMU2_CAN_LOAD_INCREMENT 0.2  // (mm) To reuse within MMU2 module
    #define MMU2_CAN_LOAD_INCREMENT_SEQUENCE \
      { -MMU2_CAN_LOAD_INCREMENT, MMU2_CAN_LOAD_FEEDRATE }

  #endif

---

So it's something else. Have you enabled #define MMU2_MENUS?

Yes. And I can go into those menus from the lcd12864 display. I can load the filaments and unload a everything that way works. Because my titan aero is so much shorter than the prusa extruder I always end up with a blob. I entered the menu from the prusa MMU2S itself and adjusted the length of filament for all 5 filaments and saved it so it load all just fine.

Ok you could try changing the values in MMU2_LOAD_TO_NOZZLE_SEQUENCE, maybe lower the last value from 50 to 30 or so. The MMU2_RAMMING_SEQUENCE should be ok, not sure...

Alright I am home for the 3 day weekend. What I really need to figure out is my gcode. Buddy this is what I am so hoping you can help with. I need to know what my gcode needs to look like. I have 4 pictures of what i currently have. It is long and i do not understand it and i just need the printer to home and start the print. I need to know what minimum mandatory gcode would look like to get this up and going..
https://imagizer.imageshack.com/v2/xq90/924/jlpTJS.png
https://imagizer.imageshack.com/v2/xq90/923/fDmpez.png
https://imagizer.imageshack.com/v2/xq90/923/NIQzxt.png
https://imagizer.imageshack.com/v2/xq90/924/FFK7lx.png

From Start gcode, remove M115 as it's for Prusa FW version check. Also the M221 might be Prusa specific so remove it, at least the 'official' gcode listing doesn't seem correct: https://reprap.org/wiki/G-code#M221:_Turn_on_AUX_V1.0.5. Here it seems to control extrusion %.


Other than those I guess it's all good. The M403 I suppose are in latest Marlin as MMU2S is.

Thank you. I tried it and it started. I still have this problem when it starts priming the first filament and the extruder spins backwards while the x axis moves in one direction and then when it moves in the other way the extruder spins the correct way. And it goes back and forth for this prime. But when it goes to the color it is going to print with it does ok. So we are making progress. Sadly these titan extruders are absolutely killing me. I am really thinking hard about building a clone prusa mk3s extruder assembly or a Bond Tech with Mosquito. What do you think? The sound of the titan extruder skipping has become like nails on a chalkboard to me. Common as it seems to have become of late. Only with the multi material printing do I use PTFE tubing. Otherwise I am direct drive with open filament hanging above feeding straight down. very low restriction path. I always have the spring tension very light on the filament and no problem. But inside the long ptfe tubing I have to crank the spring tension down so much it deforms the filament and then it binds on its way down to the hotend. Or I loosen it and it skips.

are the extruders dual gear extruders ?

I've got a bmg dual gear extruder on the sapphire pro.

I'm not convinced it's better than the mk8 on the delta.
The double gears definitely seem to grind a lot more then the mk 8 (7 ? - hang on)
this one:
Attachment 15156
That is hands down the best extruder from all 6 machines.


I think I'm up to about 8km through a 16 inch(ish) bowden tube. Never a single issue.

Whereas the bmg - only worked at all with it's bowden tube, when screwed right down to the point I can't turn it any more.
Plus grinds both sides, and it's still got a 2mm gap between the gears and the feed hole that the slightest back pressure causes flexible filament to bulge out of.

I'm going to strip it down and see if there's anythign I can do to block the gap.

Now it's direct drive, it's only got 105 mm tube that's vertical straight, so I don't have to screw it as tight.
But the gap needs blocking.
As it won't print flexibles at anything past 12mm/s.
The fixed mk8's on the klic-n-print happily knock it out at 30mnm/s.

I think sometimes the expensive, fancy extruders just don't work as well as the original simple ones.
manufacturers try and fix problems that didn't actually exist in the first place.

One other thing that might be relevant.
The bowden tube on the delta has a slightly wider bore than the one on the sapphire pro 2.
So there's very little friction on the delta and there was a lot on the original sapphire setup.

Could be an issue.

I don't think that Prusa extruders makes much difference. Remember, it is 1:1 ratio so you'll lose the Titan's etra torque. I have one Titan and it's a quite nice extruder.
If the Titan is clicking, then I think it might be trying to feed too much material too fast and if Titan is clicking, Prusa extruder has no chance. OTOH, Prusa extruder probably has the correct distance from the gears to the hotend so it might fix the situation. However, if the problem is a too long feed length, it should be fixable with tuning the lengths in Marlin and/or start gcode. At what point does the clicking happen? Can you share a video? Also if you can share a gcode-file you are trying to print would also help.
The x-axis gong back and forth while extruder moves backwards might be by design, it kinda does that on my MMU2S also when feeding filament; first it feeds it almost all the way, then retracts few centimeters and then does the actual feed. Might be a kind extra safety move as there's a possibility of a jam just when getting to the heatbreak...

Well I was under the impression that everybody with a bowden tube ran dual drive. But it is good to hear otherwise. I needed to print something large and this is the only printer i own big enough so last night I changed the extruder count back to 1, commented out single nozzle and mmu and just like that it compiled. That was all i had to do to convert back to one filament. Then I removed the bowden tube so I could just feed in a filament. I had a jam and ended up changing both the heatbreak and the nozzle. And it has been printing for 15 hours now and looks great..
https://imagizer.imageshack.com/v2/xq90/924/SSibZK.jpg
I know why there is Z banding. It is an interesting problem to correct on this machine but I know why it is and I will make it right. It is very slight and you can barely feel it in the surface with your fingernail but it is there..
https://imagizer.imageshack.com/v2/xq90/924/MKLNK4.jpg
Tonight when this is done I will reconnect everything and try again. Thank you guys for saving me some money and more headaches.

lol if that's what you call 'z-banding' you got nothing to worry about :-)

So the mumu setup feeds a direct drive extruder doesn't it ?
So all the tube from the mumu extruder to the printer actual extruder does is to guide the filament.
What you want is the big stuff that's used as a filament guide on the replicaror clones. IT's 3mm internal. Which would reduce the friction to practically nothing.
Dunno if that would help significantly - but got to be worth a try.

The 2mm stuff they use on the saffire pro2 was so tight I had real problem just pushing pla through it by hand.

Now she's direct drive - oh man :-)
Knocked out a perfect iris box last night at 0,2mm layer and 75mm/s speed.
Best one one yet.
Currently seeing if she'll print one at 0.3mm layer height.
Then I'm gonna up it to 100mm/s and see what happens.

If I can actually print a fully smooth iris box at 100mm/s and 0.3mm - that makes them quick enough to sell at a sensible price :-)

You're going to have to try the corexy system next.
That and the linear rails just makes for really precision movement.
And the things completely silent.
The ony reason you know it's even running is the slight sounds made by the filament coming off the spool.

On another note, are you now wishing you'd gone down the mosaic route ?
;-)

I dream of 100mm/s. I will tune this for speed when i get it working. To see how fast it can print good. I am not sure about the palette but I am definitely in over my head on the MMU2S. I am so close. So painfully close. I have to figure out why my extruder drive gear spins slow backwards at the start of the print. This slow speed in and out of the filament is causing jams in the heatbreak. I made the changes to my start Gcode as suggested but it still does this same thing at the very start of the print. Why does it do this @ 1:40 in this video??? https://www.youtube.com/watch?v=iICQ8sENQJs&t=

Ok the movements back and forth might just the thing that happens at the beginning of a multicolor print. PrusaSlicer adds a sequence to the beginning of the print where it loads each filament once and purges some stuff at the front of the bed, 'priming' each filament. Why the extruder moves back and forth might be just to form the tip properly, I?l have to check if my printer does that too.

But the fact that there's no filament coming out of the nozzle indicates that there's an issue with feeding the filament all the way to the nozzle. The tip of the filament on the video looks kinda bad, can you test with filament that has the tip properly cut? Also after this kind of failed load, does the filament seem like the extruder gear has grinded it?

Edit: I sliced a multicolor model in PrusaSlicer and looking at the priming gcode doesn't show that kind of moving the filament in and out. I'd really like to have a look at the gcode file you are trying to print.

OK I loaded a 5 color multi material test print into prusa slicer and sliced it. Here is that Gcode. Can you please compare this to your start gcode and tell me what i am doing wrong?

Quote:

---

Originally Posted by AutoWiz

OK I loaded a 5 color multi material test print into prusa slicer and sliced it. Here is that Gcode. Can you please compare this to your start gcode and tell me what i am doing wrong?

---

To my understanding, everything should be ok. This print doesn't seem to have the filament priming feature enabled, it just loads the first filament and starts to print. Have you tried printing it yet?

Here's the initial start gcode, standard stuff. Add mesh bed leveling command if you need to:

Code:

---

M73 P0 R137 ; progress indication
M107 ; fan off
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S240 ; set extruder temp
M140 S60 ; set bed temp
M190 S60 ; wait for bed temp
M109 S240 ; wait for extruder temp
G28  ; home all without mesh bed level

---

This sets up MMU2S so that it knows what type of filament is loaded

Code:

---

; Send the filament type to the MMU2.0 unit.
; E stands for extruder number, F stands for filament type (0: default; 1:flex; 2: PVA)
M403 E0 F0
M403 E1 F0
M403 E2 F0
M403 E3 F0
M403 E4 F0

---

This part loads first filament to nozzle. The initial load length seems low, for me it does more than double that. That could be the problem, it's just no feeding the filament far enough initially.

Code:

---

;go outside print area
G1 Y0.0 F1000.0
G1 X260 F1000.0
G1 Z0.2 F1000.0
; select extruder
T0
; initial load
G1 E29.0 F1073.0
M73 P0 R137
G92 E0.0

---

For some reason does another loading of first filament, not sure if this actually does anything because the filament is already loaded. Don't know why this is here, but I have it too so apparently it's needed or just redundant stuff that Prusa team hasn't cleaned away.

Code:

---

G92 E0.0
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
T0
; Filament gcode
G1 Z0.500 F4800.000
;BEFORE_LAYER_CHANGE
G92 E0.0
;0.3

---

Moves to purge tower position

Code:

---

G1 E-1.00000 F2100.00000
G1 Z1.100 F4800.000
G1 Z0.500
;AFTER_LAYER_CHANGE
;0.3
G1 E-2.00000 F2100.00000
G1 Z1.100 F4800.000
G1 X101.016 Y209.785
G1 Z0.500
G1 E3.00000 F2100.00000
;-------------------------------------
; CP WIPE TOWER FIRST LAYER BRIM START

---

So the initial load part seems to be the only problematic section.

I suggest you check the Printer Settings -> Single extruder MM setup section, this is what I have:
Attachment 15247

Edit: actually the initial load section seems to be in the Start gcode-section, this is what I have in there:

Code:

---

M862.3 P "[printer_model]" ; printer model check
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.9.0 ; tell printer latest fw version
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling

; Send the filament type to the MMU2.0 unit.
; E stands for extruder number, F stands for filament type (0: default; 1:flex; 2: PVA)
M403 E0 F{"" + ((filament_type[0]=="FLEX") ? 1 : ((filament_type[0]=="PVA") ? 2 : 0))}
M403 E1 F{"" + ((filament_type[1]=="FLEX") ? 1 : ((filament_type[1]=="PVA") ? 2 : 0))}
M403 E2 F{"" + ((filament_type[2]=="FLEX") ? 1 : ((filament_type[2]=="PVA") ? 2 : 0))}
M403 E3 F{"" + ((filament_type[3]=="FLEX") ? 1 : ((filament_type[3]=="PVA") ? 2 : 0))}
M403 E4 F{"" + ((filament_type[4]=="FLEX") ? 1 : ((filament_type[4]=="PVA") ? 2 : 0))}

{if not has_single_extruder_multi_material_priming}
;go outside print area
G1 Y-3.0 F1000.0
G1 Z0.4 F1000.0
; select extruder
T[initial_tool]
; initial load
G1 X55.0 E29.0 F1073.0
G1 X5.0 E29.0 F1800.0
G1 X55.0 E8.0 F2000.0
G1 Z0.3 F1000.0
G92 E0.0
G1 X240.0 E25.0 F2200.0
G1 Y-2.0 F1000.0
G1 X55.0 E25 F1400.0
G1 Z0.20 F1000.0
G1 X5.0 E4.0 F1000.0
G92 E0.0
{endif}
G92 E0.0

---

Try copying the lines after ;initial load to your start gcode