Summary

During MultiColor 3D printing the default way of purging the old colorduring transition between colors is to use a purge block or wipe tower. Themain problems with purge blocks are that they must be printed on everylayer even if there are no color changes, and they take up space on theprint bed.

We’ve designed a new retractable purge mechanism. It mounts to the sideof your 3D printer and works with any slicer (i.e. Slic3r (PE), Simplify3D,SimplyColor3D) to reduce waste and decrease purge time. With ourretractable purge mechanism, material is only purged when a color changehappens which mean fewer purges and faster prints. The retractable armallows it to work on printers where the nozzle cannot reach past the edgeof the print plate. The Retractable Purge Mechanism turns color transitionpurge into little blobs and shoots them into a waste bin.

Here is a normal speed video of a real life RPM actuating during a print.

Here is a marketing video that explains what the RPM does in an overlysimplistic and cartoony way.

BigBrain3D

The originalRetractable PurgeMechanism, forMultiColor 3Dprinting, Replacespurge blocks &wipe towers

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updated 6. 1. 2020 | published 22. 12. 2019

3.00 hrs

1 pcs

f

0.20 mm

k

0.40 mm

h

1

24.00 g

d

MK3/S

Some of the parts needed are difficult to find (like the tension springs), ordangerous to prepare (like the tack and washer), or tough to make (likethe 2x47mm kapton tape). And buying each part individually is much moreexpensive, especially considering separate shipping or gas to drivebetween stores. For these reasons we've made a hardware 'kit' availableon our web site here: RPM Hardware kit The kit will save you time andmoney, so please consider buying the kit from us to help support ongoingdevelopment, or even just tipping us if you think this 'thing' was useful.

We have set the license for this as Non-Commercial and allowed remixesbecause we want users to be able remix for their own printers since thesefiles currently only support the Prusa i3 MK3S.

Thank you =D BigBrain3D

3D Printers > 3D Printers - Upgrades

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prusamk3s prusamk3 prusai3mk3smmu2s prusai3mk3s

prusai3mk3mmu2 prusai3mk3 prusai3mk2 prusai3 pallete

pallet palette2 palette originalprusamk3s

originalprusamk3 originalprusai3mk3 originalprusai3

mutlicolor multicoloured multicolour multicolors3dprinting

multicolors3dprint multicolor multcolor mosaicpalette2

mosaicpalette colorprint colorchange

Print 1 each of these 10 parts: -Action -Arm -Bracket -Cage -Cap left -Catcher -Connecting arm -Flicker -Mount right -Wedge -(Optional) Blob Bin(Print settings: zero(0) top solid layers & zero(0%) percent infill)

If you have the Bear upgrade you need this too.

Assembly is best done in a specific order. Written assembly instructionswith pictures.

Video step-by-step assembly instructions.

If you are preparing the Tack and Washer yourself then this google docexplains how to do that, it also contains written instructions with picturesof the entire assembly procedure.

In case of any difficulty during assembly, please post a comment here, orin our forum here.

Move the PINDA probe as far away from the bed as possible and still ableto detect the bed on z home and level. This is to avoid the purgemechanism linkage during actuation. Remember to redo the "First layercalibration' if you move the position of the PINDA probe.

Turn off 'Crash detection' from the Printer control panel -> Settings ->"Crash Det." Make sure this is "OFF" !!!

Before you start printing you need to determine the proper position of thepurge mechanism. Run this gcode but change the number on the 'Changethis line' until the nozzle is directly over the center of the tack: " ;**Beginpurge deployment location test** G28 X ;home X M907 X800 ;set motorcurrent G1 X200 F12000 ;move to position slow G4 S0.1 ;momentarypause G1 X250 F12000 ;depress action arm fast G1 X256.6 F1000;Change this line (move nozzle over tack slow) G4 S2 ;momentary pauseM907 X550 ;set motor current back G1 X100 F12000 ;move to center of Xaxis ;**End purge deployment location test** "

Once the exact location of the deployed purge mechanism is know thenyou can test the purge with this code: " ;**Begin purge test** G28 X M907X800 G1 X200 F12000

G1 X200 F12000 G4 S0 G1 X250 F12000 G1 X256.65 F1000 ;Change thisline (1 of 2) M107 G92 E0 G1 E0.8 F2100 ;issue G92 E0 G1 E40 F200 ;1stpurge M106 S255 ;blob cooling G4 S12 ;blob cooling G92 E0 G1 E-0.8F2100 G1 X240 F12000 G1 X256.65 F3000 ;Change this line (2 of 2) G1X240 F12000 ;**End purge test** "

Print Settings: Optimal print settings are as follows: Slicer: Prusa SlicerPrint setting: .2mm Quality MK3 Infill: 20% Notes: We use PLA and bedtemp of 65C, we also cover our MK3S with a plastic bag in place of anenclosure. This helps keep the print perfectly flat.

Required Hardware -1 standard steel thumb tack (modified shortened)-2 tension springs (.5mm wire gauge, 5mm ID, winding 8.8mm long,20.5mm overall) -Kapton tape -> 2mm wide X 47mm long -60mm ofAluminum tape -An M4 washer with notch cut out -2pcs M3x10mm Flathead Allen screw -2pcs M3x10mm Socket cap Allen screw -1 tube ofsilicone grease (it’s the only grease that won’t harm plastic) -3D printedparts

Buy a Hardware kit here

Gcode additions

You will need to make some additions to the 'on tool change' section ofyour slicer.

1)Make sure you are in Expert mode. 2)Import multi-part 3D model. 3)Turnoff the purge block wipe tower. 4)Paste the custom purge script (foundbetween the double quotes below) into the 'Tool change G-code' text box.

Here is a video showing step by step how to: https://youtu.be/KRk0z6-X93A

" {if current_extruder != next_extruder} ;*Begin pre-tool change gcodeM907 X800 ;set current of X motor. May need to set Y as well if yourprinters head moves on x & y

M106 S0 ;turn off fan G92 E0 ;reset extrusion distance G1 E-0.8 F2100;retract G1 Y100 F12000 ;Break string before Z lift G1 X200 F12000 ;movehead into position

G91;Change to relative position {if layer_z < 15.0}

G1 Z15

{endif} G90;Change to absolute position

G4 S0 ;clear movement buffer G1 X250 F12000 ;move head to purge zoneG1 X254.6 F1000 ;extend purge arm ;*End pre-tool change gcode

M702 ;unload filament T{next_extruder} ;this code -> T{next_extruder}signifies the extruder tool change

;*Begin after tool change purge gcode G1 X200 F12000 ;move headinto position G4 S0 ;clear movement buffer G1 X250 F12000 ;move headto purge zone G1 X254.6 F1000 ;extend purge arm M107 ;turn off fan G92E0 ;reset extrusion position G1 E0.8 F2100 ;issue after retract G92 E0;reset extrusion position G1 E40 F200 ;1st purge extrude onto thumb tackM106 S255 ;turn on fan G4 S12 ;blob cooling G92 E0 ;reset extrusionposition G1 E-0.8 F2100 ;retract extruder to prevent oozing G1 X240F12000 ;whack blob off tack 1 G1 X254.6 F3000 ;reset for another blobwhack G1 X240 F12000 ;whack blob off tack 2

;each of these additional sections is a copy of the block above. You need 1block for each blob. G1 X200 F12000 G4 S0 G1 X250 F12000 G1 X254.6F1000 M107 G92 E0 G1 E0.8 F2100 ;issue G92 E0 G1 E40 F200 ;2nd purgeM106 S255 ;blob cooling G4 S12 ;blob cooling G92 E0 G1 E-0.8 F2100 G1X240 F12000 G1 X254.6 F3000 G1 X240 F12000

Print Files (.gcode) DOWNLOAD ALL FILES

G1 X200 F12000 G4 S0 G1 X250 F12000 G1 X254.6 F1000 M107 G92 E0G1 E0.8 F2100 ;issue G92 E0 G1 E40 F200 ;3rd purge M106 S255 ;blobcooling G4 S12 ;blob cooling G92 E0 G1 E-0.8 F2100 G1 X240 F12000 G1X254.6 F3000 G1 X240 F12000

G1 X200 F12000 G4 S0 G1 X250 F12000 G1 X254.6 F1000 M107 G92 E0G1 E0.8 F2100 ;issue G92 E0 G1 E40 F200 ;4th purge M106 S255 ;blobcooling G4 S12 ;blob cooling G92 E0 G1 E-0.8 F2100 G1 X240 F12000 G1X254.6 F3000 G1 X240 F12000

M907 X650 ;set the current back to normal ;End after tool ChangePurge gcode {endif} "

On Start Gcode priming In the 'start' gcode section of your slicer thereis a line to prime the nozzle. You can do this instead with the purgemechanism BUT you must watch carefully because if the nozzle is notprimed then the exact amount of filament may be less than 40mm and amalformed purge blob may result. Just be ready to remove the blobmanually with tweezers if this happens. Doing 2 or more purge blobs mayhelp this. Just replace the priming line with this:

;Replace on start priming line with this M109 S215 ; wait fortemperature to be reached G90;Change to absolute position G1 Z15 ;raisehead for purge mechanism bed clearance

G1 X200 F12000 ;move head into position G4 S0 ;clear movement bufferG1 X250 F12000 ;move head to purge zone G1 X254.6 F1000 ;extendpurge arm M107 ;turn off fan G92 E0 ;reset extrusion position G1 E0.8F2100 ;issue after retract G92 E0 ;reset extrusion position G1 E40 F200 ;1st purge extrude onto thumb tack M106 S255 ;turn on fan G4 S12 ;blobcooling G92 E0 ;reset extrusion position G1 E-0.8 F2100 ;retract extruderto prevent oozing G1 X240 F12000 ;whack blob off tack 1 G1 X254.6F3000 ;reset for another blob whack G1 X240 F12000 ;whack blob off tack2

;add as many of the next section until you get a good prime G1 X200F12000 G4 S0 G1 X250 F12000 G1 X254.6 F1000 M107 G92 E0 G1 E0.8F2100 ;issue G92 E0 G1 E40 F200 ;2nd purge M106 S255 ;blob cooling G4S12 ;blob cooling G92 E0 G1 E-0.8 F2100 G1 X240 F12000 G1 X254.6F3000 G1 X240 F12000

M907 X650 ;set the current back to normal ;End Replace on start primingline with this**

4.8 MB

3.00 hrs f 0.20 mm k 0.40 mm h PLA 24.00 g

updated 22. 12. 2019

Model Files (.stl, .3mf, .obj, .amf) DOWNLOAD ALL FILES

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1x-purge-kit-layout-v10-rev-a-1x-kit-3hrs-rev-p.gcode

purge-cage-v10-rev-a.stl

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purge-cap_left-v10-rev-a.stl

purge-catcher-v10-rev-a.stl

purge-flicker-v10-rev-a.stl

purge-mount_right-v10-rev-a.stl

purge-wedge-v10-rev-a.stl

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