Two Motor - Multi-Colour Printing - Need your help.

Hey Guys,

I'm trying to do something that I don't think has been done before. But I don't think it would be very hard... at least for someone with just a little more experience. Pretty much I'm hoping to crowd-source the solution to this problem.

I want to try and create a multi-colour extruder that will print up to 5 (possibly more) different colours, with one nozzle, using only a single board (i.e. two motors). This should drastically reduce the cost to implement the solution. This means no extra boards, no extra cables, only one motor, and then some hardware and some printing.

The concept is based off the two images in my poster. Their "Widgets/Parts" can be found on Thingiverse at the following locations:
https://www.thingiverse.com/thing:2867089 - 2-3-4 way Splitter (doesn't have to be this one... it is just representative)
https://www.thingiverse.com/thing:3123202 - Multi-Extruder

The problem that I have found, at least I expect that it is a problem, the second motor is not extruding, and thus only gets triggered on a change filament command, but then it uses the same extruder once the filament is selected. I assume that no slicer is set up to do this, but I figure it wouldn't take much code. I can write the pseudo-pseudo code for it:

-retract current filament
-set temp and wait
-switch filament
      -move motor 2 appropriately
-purge nozzle and complete wipe tower or wall
-continue printing until next filament change

The problem is that this needs to get built into the slicer, and while I figured I could do it manually for objects that have entire layers of different colour, multiple changes per layer would appear to me to be very difficult to do manually. Thus my search for help... I'm sure that there is someone out there who is capable and eager to help develop the code in a slicer to improve the community... I think that is what REPRAP is about.

I am pretty confident that I can work out the design files to be able to modify the Y Splitter for more (I'm looking for 5) and engineer it so that the Teflon tubes work well (I would also like to see if I can add a filament sensor). As well as verifying the extruder design for what we are trying to achieve.

So let us see what we can do together.

As a start and a contribution to the project, how about first making a prototype integrating the two "ideas" you got from thingiverse, test "manually" (power the hotend, wire up the motors to some controllers you can send command to or even turn by hand), to prove it works.

The "y splitter" is just elementary stuff to make. The main issue is the retraction length this one plus hotend requires.

Edited 1 time(s). Last edit at 10/26/2018 12:32AM by MKSA.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Hi, well i dont know if i understeed all your project and also im not an expert, just a cople of months, but as i have tried on my machine which is a doble extruder marlin an i use whith chimera hotend and marlin I use gcode for mixing colors thrue my dysplay i have preconfigurated some and y chouse 75% 25% or 50% 50% and so on and works well but if you use just one say 0 100 the one empty sturts to get the other filament back , as what understend you are tring to make a diamant extruder but whith 2 motors so you only pushes 2 filaments or all at he same time? if you have 3 feedin that my bee a problem maybe 4 is easier 2 on one motor and 2 on the other

also I dont retract it just stop feeding and the other acelerates, and dont even pause, so you can have 16 virtual tools.

hope that helps

This is just the prusa Multi material 2 without the filament selector and by passing the dedicated electronics

I think this is a bit on the noise.... buy a real Prusa MM 2

Quote

-retract current filament
-set temp and wait
-switch filament
-move motor 2 appropriately
-purge nozzle and complete wipe tower or wall
-continue printing until next filament change

If you use RepRapFirmware on a suitable 32-bit board, you can do all of that using the standard firmware build. Just put GCode commands to do those steps in the tool change macro files on the SD card. No need to change either the firmware or the slicer.

Here's a forum thread started by someone who has done something similar: [forum.duet3d.com].

Edited 1 time(s). Last edit at 10/26/2018 10:45AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

How do specify the specific filament selection... I guess I'm a newbie. (Thus the reason for the help).

Wouldn't the slicer want to have the discrete temps for the various nozzles associated with the materials, and wouldn't it be trying to use different motors to extrude... Doing all this to generate the gcode for a multi colour print.

Edited 1 time(s). Last edit at 10/26/2018 06:57PM by Raxen.

When the slicer wants to switch filament, it inserts a T# command in the GCode stream where # is the number of the tool with the required filament. You use one too number per filament. The new tool number may correspond the a different nozzle, or to the same nozzle with a different extruder drive, depending on the printer. You would normally assign one tool number per filament used in the print.

Heating or cooling the new tool can be done using commands generated by the slicer; but when using RepRapFirmware it doesn't have to be done that way. This is because the active and standby temperatures of each tool can be set individually and are remembered by the firmware, which adjusts the temperature automatically when you change tool.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
The new tool number may correspond the a different nozzle, or to the same nozzle with a different extruder drive, depending on the printer.

Would this work if the tool change had the same extruder and same nozzle? The only difference in the tool change is the position of the filament selector (the second motor). And perhaps a different temp.

Quote
Raxen

Quote
dc42
The new tool number may correspond the a different nozzle, or to the same nozzle with a different extruder drive, depending on the printer.

Would this work if the tool change had the same extruder and same nozzle? The only difference in the tool change is the position of the filament selector (the second motor). And perhaps a different temp.

Yes. In RepRapFirmware you specify the heater and extruder drive numbers when you create the tool (which you normally do in the config.g file on the SD card, which is run automatically when the machine starts up). Also you can specify if necessary the tool offsets, X and Y axis mappings, fans used, and active and standby temperatures. In your case you could create two tools that are identical, except for the active and standby temperatures if you want the firmware to manage them.

Each tool has its own set of G-code macro files that get run when the tool is selected or released. So you would put the command(s) to set the filament selector to the correct position in those macro files. See [duet3d.dozuki.com] for the documentation.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Okay, seems reasonable and gives me a hope to make something work... A place to start my research.

My last question, would you know if this is similar for Marlin firmware? My printer natively runs Marlin and a conversion to something else may have unintended frustrations.

Thanks for the help.

No, the philosophies of RepRapFirmware and Marlin are completely different. With RepRapFirmware, everything is configured at run time using M-codes and G-code macro files. Whereas with Marlin, the tool definitions and tool change procedures have to be baked into the firmware source code, which you then compile and upload to your electronics. You would need additional program code to handle your filament selector. You might be able to use the support code for the Prusa MMU as a basis, if your filament selector works in a similar way. If you want more advice on how to do this in Marlin then I suggest you start a thread in the Firmware/Marlin section of this forum.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

i basically do this on my rotary extruder 1 motor drives the other selects which hotend. i used the [www.marlinkimbra.it] firmware using NPR2 i did have to add some code to firmware. but now any slicer will work just using the t command.

actually looking at the NPR2 it does what you want to do . [3dprint.com]