Introduction: UP Mini Dual Extruder With E3D Chimera

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This is a write-up about the conversion I did to my UP mini. It had strange electrical issue and I did not want to spent the time to fix it. So I spent much more time to convert it to a dual extruder printer with an E3D Chimera (of course you can use an E3D Cyclops as well, if you desire).

First of: Thanks to Woodlake (Up mini Adjustable Bed), 0110-M-P (Compact Direct Drive MK8 Bowden Extruder) and Elzariant (LPA Fandcut v6). These designs safed me some time finding my own solution. although I had to modify them a little bit to fit my needs.

This conversion keeps the full 120x120x120mm built area of the up mini.

If you don't want to use dual extrusion you may also use this guide to:

  1. - convert your Up Mini to standard (opensource) RepRap electronics
  2. - convert your Up Mini to any Hotend (E3D V6, BigBooster, FilaHead, etc.) or Extruder (E3D Titan, Bondtech, etc.) you like
  3. - mount the PSU inside your up mini

Step 1: BOM , Printed Parts and Parts Choice

    • 1x LM6LUU Bearing (you may use 2 of the original LM6UU bearings if you desire)
    • 1x E3D Chimera+ (24V, Air-Cooled)
    • 2x Extruder
    • 2x Nema 17 Stepper Motor
    • 1x 40x40mm Fan, 24V (part cooling)
    • 3x M3x10mm Countersunk Screw
    • 5x M3x10mm Cap Head Screw
    • 4x M3x12mm Cap Head Screw
    • 10x M3x14mm Cap Head Screws
    • 1x M3x20mm Button Head Screw
    • 2x M3x30mm Cap Head Screw
    • 4x M3x40mm Cap Head Screw
    • 8x M3 Washer
    • 8x M3 Hex Nut
    • 2x M4x14mm to M4x20mm Screw (to mount the 608 bearing in the extruder idler arm)
    • 2x 10x10x1mm, 140mm long Aluminium L-profile(this part is lighter and stiffer then the 12x3mm Aluminium bar which Woodlake uses - the y-carriage will collide with the printers frame if you use my solution. This can be solved either in software or by making a small cut into the Up minis frame. I choose the 2nd solution)
    • 2x 608 Bearings
    • 2x Filament Drive Wheel for 1.75mm (one like this)
    • 2x Bowden Coupling with M6 thread
    • 1x IEC Connector Chassis Pass-through (I don't know the correct name - I mean something like this)
    • 2x Sheet metal screw for mounting the IEC connector (3x5mm or somethinge along those lines)
    • 1x 60mm Fan, 24V (PSU cooling)
    • 1x 5015 Radial Fan, 24V (electronics cooling)
    • 1x Microcontroller with 5 Stepper drivers for 24V (I used the MKS Gen L, if you want to use anything else you have to change the "MKS Gen L mount")
    • Interface for 3D printer (in the beginning I used a Reprap fullgraphic controller - but I damaged the encoder due to dropping issues...afterwards I replaced it with an Raspberry PI zero W running Octoprint)
    • 24V PSU - max measurements 43mm x 110mm x 250mm (the 43mm and 110 mm measurements are essential - bigger PSUs will simply not fit and collide with the y- or z-carriage - in the first version of this printer I used the standard PSU with 19V but this was quiet underpowered - heating up everything simultaniously worked fine but took about 7 minutes for the hotends and 10 minutes for the bed - PLA temperatures 210/210/50 - so later on I desided to use a Meanwell HLG240h-24 (24V 10A) PSU instead)

    Attachments

    Step 2: Printer Disassembly

    I did not take any pictures of the disassembly in the first place. But I changed some part designs and later on had to disassemble the x- and y-axis again. Bad for me - good for you. Please note: the parts I disassemble are NOT the original UPmini parts. So your printer might look a little bit different - overall the steps are the same.

    I don't have any pictures of the electronics disassembly, but this is pretty straight forward: remove all plugs, unscrew all screws. Et voilá - everything comes apart.

    X-Axis - disassembly

    The assembly of the x-axis is quiet simple. First remove the Idler mount for the x-axis belt. This one is fixed with 2 screws to the main frame. You can access them from the back of the printer.

    Next you can remove the 4 screws holding the x-axis smooth rods and remove the complete x-axis assembly (smooth rods, x-carriage, extruder, hotend, belt).

    Y-Axis - disassembly

    To disassemble the y-axis first remove the small ribbon cable on the bottom of the z-carriage. Be carefull not to damage the cable or the connector. Next you can remove your built plate (on the stock version this would be the perf board). Unscrew the 2 screws in the center of the bed PCB and slide it out of the frame. Again: be careful not to damage the fragile ribbon cable.

    After this you can start to dismantle the y-carriage. Remove the 6 screws holding the bearings and the belt mount in place. I recommend leaving the belt and belt clamp inside the printer. There is no need to disassemble these and the re-assembly is very...annoying.


    Step 3: Extruder / Hotend Assembly

    I will not discuss every detail of the E3D Chimera Assembly. This is well documented by E3D:

    E3D Chimera+ Assembly Guide

    X-Carriage Assembly:

    The assembly of the x-carriage is pretty straight forwared:

    Mount the Chimera+ cold end (= heatsink) to the x-carriage using three M3x10mm countersunk screws. Then push in the bearings. Insert the belt in the corresponding slot and lastly add the belt tensioner to the belt (next to the mounting clamp). I recommend you assemble the rest of the hotend after you installed the carriage to the printer. The most recent Version of the x-carriage has a hole in the "arm" which pushes the x-endstop. This hole is for an M3 screw so you can adjust the x-travel (otherwise the carriage will collide with the frame).

    The pictures also show a suggestion for routing the wires of the hotends.

    X-Axis assembly:

    Assembling the x-axis is really simple. Just do everything you did to remove the parts from the printer in reverse. The only difference being the new x-carriage and the new x-axis-idler-mount. The new idler mount allows for more travel in the x-direction in order to let the nozzles move out of each others way.

    Afterwards install the x-axis smooth rods inside the printer, put the belt on the x-motor-pulley and at last mount the new idler.

    To mount the new x-axis belt idler just put the belt inside it and push through the idler (gear with 2 bearings). Mount the top part of the idler to the z-axis-clamp (top screw) using a M3x10 screw. Afterwards use a M3x20 screws from the outside and guide it thorugh the idler. You can use an M3 nut to adjust the belt tension.

    Extruder Assembly:

    For the extruders I used a MK8 Bowden Extruder based on the design by 0110-M-P. The Idler arms are mostly his design (I just removed the slot for the M3 screw), but I changed the design of the extruder body a little bit (removed the mount section for i.e. 2020 extrusions and the slot for the top bearing ,made a bigger hole for the coupling so I could use couplings with M6 thread).

    First you have to drill the holes for the extruder-motors into the frame of the printer. The picture above shows a suitable position for the motors. I used a 3.5mm drill bit for the M3 screws and step drilled (3.5mm, 5mm, 8mm) the center hole for the motor shaft. Use the part "Nema17 Spacer" to drill the holes in the right position. After drilling the holes the spacer goes between the motor and the frame.

    First test that your holes fit the motors hole pattern. Always remember: measure twice, cut once! Test-fit the extruder-motors (with spacers) using 4 M3 screws. After that you can mount filament drive wheel to the stepper motor (this will also ensure that the motor does not fall down if you remove the screws). To get the position of the drive wheel kina right put the extruder body next to the stepper while mounting the drive wheel.

    Afterwards you can assemble the rest of the extruder. First (!) mount the bowden coupling to the extruder body. Mount the extruder body using 3x M3x14mm screws. Secure the 608 bearing between the idler arms using one M3 screw. Afterwards mount the idler arm on the extruder body using an M3x30 screws. Push 2 M3 nuts into the corresponding crevice. Maybe you have to heat them up using a lighter or an soldering iron to get them in easyly - make sure they are in line with the hole for the M3 screw! Let them cool down a few seconds. Put the M3 washers and the spring onto the M3x40mm screw and use it to create tension between the idler and the drive wheel.

    Step 4: New Y-carriage and Improved Heated Bed

    Because of certain constraints of the original y-carriage I opted to built an improved one - so now you can get the maximum of x-travel an the nozzle won't hit the carriage. For this new carriage you will need:

    • 1x Springsteel Sheet, 140x140x0.5mm (as removable built plate, got mine from Christian R.)
    • 1x 140x140 high temperature magnet sheet with adhesive (got mine from Christian R.)
    • 1x Aluminium Sheet, 140x140x2.0mm (as a heat spreader)
    • 1x 140x1x1 mm Aluminium L-Profile
    • 1x Up mini x-carriage
    • 4x M3x15 (female/female) Spacer
    • 8x M3x5 countersunk screws
    • 4x M3x5 screws
    • 4x M3 nuts
    • 8x M3 Nylon washer (so you don't tighten the spacer against the pcb heater)
    • PEI sheet (140x140mm, I used this one and cut it to size)
    • Capton tape

    Assembly

    First center the PCB heater on the 140x140x2.0mm Aluminium sheet as shown in the picture (mine overhangs a Little bit because I used a scrap Piece I had laying around). Use a sharpy to mark the corner holes of the PCB. Drill out the holes from the aluminium plate and make them countersunkt from one side. Be carefull - don't drill to deep.

    Now you can drill the holes to fix the L-profiles to the "stock" y-carriage. Drill the holes as shown in the picture. Don't drill the holes to mount the PCB / bed on the carriage yet! Mount the L-profiles to the y-carriage usint the 4 M3x5 screws and nuts.

    After this position the heater PCB ontop of the y-carriage with L-profiles and mark the corner holes. Drill them out and attach the Nylon washer and M3x15mm spacers to the Aluminium L-profiles. After this you can install the y-carriage inside of the Printer.

    Now plug in the ribbon cable for the heater PCB and fix the Thermistor cartridge to the bed using a piece of capton tape. Screws the heater PCB with the Aluminium plate ontop to the new y-carriage using the remaining M3 Nylon washers.

    You are done now - If you want, you can add the removable built sheet now. I ran my first test prints without it.

    Step 5: Electronics Assembly - PSU

    I wanted to include the PSU inside the printer. So I removed the plastic enclosure of the PSU and desoldered the connectors for AC and DC from the PSU.
    I created a new enclosure including a fan to compensate for the higher temperatures inside the printer. I will only show some pictures and not show step by step instructions. If you have any problems - ask a professional electrician. I am NOT a professional electrician.

    Mains Power (AC) can be dangerous and hurt or kill you or set everything on fire!

    Attention: After Assembling the printer with the standard 19V power supply i found out that it took ages to heat up everything. So I switched to an Meanwell hlg240h-24 - this is the only PSU I found that would fit inside the printer as well, has no fan and is rated for operating temperatures up to +70°C (at 60°C ambient temperature with 230VAC input the PSU will still output 100% of it's capability - with 110VAC input only ~80%). When you use this PSU you can ignore the following description. Just mount it (using some screws) and wire it up.

    Step 6: Electronics Assembly - Microcontroller

    The wiring of the MKS Gen L is pretty straight forward. Just follwo the wiring diagram. You can reuse most of the up minis connectors. Only the endstops have to be changed (the original connectors short ground to 5v on the board).

    At the beginning I used DRV8825 stepper drivers but I changed them to A4988 because the DRV8825 gave me an annoying spool whining. If you use different ones (A4988, TMC2100, etc.) be sure to place the in the right direction - otherwise you may kill your driver and your electronics.

    After wiring everything up you have to adjust the stepper current for all steppers. For the original Up mini Steppers 0.6 Ampere, the extruder steppers I bough are designed for 0.4 Ampere.

    Step 7: Firmware / Slicing

    Firmware

    For the firmware I choose marlin (current version can be downloaded in step 1).

    There are only two parameters you have to change in the configuration.h file.

    The first is:

    #define z_max_pos 116.8

    This value sets the position of the z-endstop - so it determins the distance between your heated bed and the nozzle. This value is crucial for getting a good first layer (I plan on using manual mesh bed leveling in the long term - but I have to check on how to use it proberly).

    The second beeing:

    #define HOTEND_OFFSET_X {0.0, 19.3}

    I really do not know why I have to use a value of 19.3mm for the second nozzle. The E3D documentation states 18mm. All of my calibration (steps per mm) prints come out good. So I may have to look into this again sometime.

    Slicing

    The setup is really simple and uses standard components (E3D Hotends, Bowden Extruder) so most slicers should work. At the moment I am using Slic3r.

    Here are the start- and end-gcodes I use:

    ;startgcode
    G28 ; home all axes
G1 Z110;
G28 Z0; home z again - axis drops down without power and z-endstop is triggerd anyways
G1 Z5 F5000 ; lift nozzle
    ;end gcode
M104 T0 S0 ; turn off temperature Hotend1
M014 T1 S0;turn off temperature Hotend2
M140 S0; turn of temperature Bed
G28; home 
M84     ; disable motors
M106 S0;

    The only "special" thing when using the UP!mini is the start gcode. The z-axis drops down if the power is turned of. So I home it, move it up a bit and home it again to get an accurate z-position.

    Step 8: Impressions and Print Results

    To come.

    I was workin on this instructable for quiet a long time. The printer printers ok-ish. I didn't have the time to dial in all settings yet. Single-extrusion works great, dual extrusion...works ;)

    What is missing at the moment is a part cooling fan - this is in the work right know. I have multiple designs but don't know, which one will work the best (dual 40mm, single 40mm, single 5015 blower, etc.).

    Step 9: Obsolete Steps - Aka: Tried and Didn't Work As Planed

    Bed-Assembly using stock y-carriage

    In the meantime I built a different version of the bed because the original design had a flaw while using dual extrusion. The nozzle of one extruder would hit the notches on the side which hold the perf-board / built plate in place - this would effectifly limit your x-travel on the first layers to about 70mm. To see how the improved y-carriage is assembled see step 5. The new y-carriage also removes the need to cut a notch into the printers frame.
    The assembly of the y-axis is a little bid fiddely. But it is worth the time and the effort to get a bed you can level manually. And honestly: on a printer this size you level it once and are done for a very long time. You can follow the Instructions by woodlake to assembly the Adjustable Bed for the printer - you will just use the 10x10x1 mm L-profile Aluminium instead of the flat 12x3mm parts: Assembly Instructions for the y-axis by Woodlake The pictures show the assembled y-carriage. While assembling consider 3 things: 1. You have to mount the Aluminium profiles "reverse" (the printed part called "Adj_Bed_-_Clip" should be flush on the front, not on the back of the printer) 2. You will need to cut a small gap into the printers frame or either the y-axis will not move freely back an forth. 3. Due to "reversing" the Aluminium profiles the bed pcb is a little bit more backwards on the y-carriage. So you need a different version of the "adjustable heated bed support". This file is included in the downloaded files - thanks to Woodlake again for the great design-inspiration. To use a "standard" ATMEGA2560 based microcontroller for the heated bed and controll the temperature using a PWM signal you have to desolder the black part from the heater PCB and jumper the solder pads. Also you have to put a thermistor on the bottom side of the heated bed. You can fix it to the bed using capton tape. The Marlin-Version I provide has PID for the heated bed enabled. Please re-run Marlins PID-Autotune to check if these values suit you - I got greate benefits from using prober values (with Marlins stock values it took about 15 minutes to get to 50°C, after PID Tuning it takes about 1 minute to get to 65°C)

    New y-carriage

    Because of certain constraints of the original y-carriage I opted to built an improved one - so now you can get the maximum of x-travel an the nozzle won't hit the carriage. For this new carriage you will Need:

    • 1x Springsteel Sheet, 140x140x0.5mm (as removable built plate, got mine from Christian R.)
    • 1x 140x140 high temperature magnet sheet with adhesive (got mine from Christian R.)
    • 1x Aluminium Sheet, 140x140x1.5mm (as a heat spreader)
    • 1x Aluminium Sheet, 140x140x2.0mm (as a new y-carriage)
    • 5x M3x10 (female/female) Spacer
    • 10x M3x5 countersunk screws
    • 5x M3 Nylon washer (so you don't tighten the spacer against the pcb heater)
    • PEI sheet (140x140mm, I used this one and cut it to size)

    First center the PCB heater on the 140x140x2.0mm Aluminium sheet as shown in the picture (mine overhangs a Little bit because I used a scrap Piece I had laying around). Use a sharpy to mark the corner holes and the center hole of the PCB. repeat the same for the 1.5mm thick aluminium sheet. Make a mark 5mm offset from the center hole - this is the alignment Point for the original y-carriage. Mark the holes for the y-axis-bearing holders and the belt clamp. To do this put the orignal y-carriage onto the 2.0mm thick aluminium sheet and align it using the 5mm offset point. Mark the holes for the belt clamp, and the bearings. The bearings will need the hole for the screw AND the slotted holes right next to the screws. Be Aware: These holes are only needed in the 2.0mm thick y-carriage plate - the top plate only Needs the Corner and center holes (blue marks). Cut / drill everything out. To drill the holes I used a 3mm drill bit. To cut out the slots for the bearing holders I used my Dremel. Make sure you don't drill the holes for the countersounk screws to deep - otherwise they won't hold the spacers in place. Now you can assemble everything. Mount 5 M3 spacers to the 2.0mm thick Aluminium plate (y-carriage) using M3x5 countersunk screws. Mount the carriage into the frame. First attach the belt-clamp, then the bearing holders. Make sure everything fits properly and rides smooth. Afterwards put an Nylon washer ontop of all M3 spacer, put on the PCB and the 2.0mm thick aluminium sheet. Don't forget the thermistor and the ribbon cable. You are done now - If you want, you can add the removable built sheet now. Bed Leveling with the "new" heated bed Due to the small built size I opted to not include a mechanism for the bed leveling. After assembly I found that a mechanism for this could be helpfull - espacially if you have bed luck and the Aluminium Sheets you ordered are not flat. Weight Comparison The original (folded steel) y-carriage inlcuding the aluminium-bars for the adjustable has a weight of around 141g. The assembled bed weights in about 273g with a perfboard and 302g with an aluminium built sheet (counting in the PCB, but not the bearings and the belt clamp). The new 2.0mm aluminium plate carriage has a weight of about 115g, including the PCB heater and the Aluminium built plate (1.5mm) the overall weight Comes together to 250g. This weight does not include the removable steel-sheet and magnet. Without the removable built plate the weight of the y-carriage with heated bed is about the same in the old and new Version. Adding the removable built plate will add about 180g. In theory this means the acceleration for the y-axis has to be decreased bei 50% to keep the dynamic forces equal in the new and original version. I set relativly conversertive acceleration values from the beginning on so I did not need to reduce the acceleration further.

    Mount original PSU inside the Printer

    Whenever I wire something up dealing with mains power it gets checked by a professional.


    The steps which requiere electrical wiring are the following. Everyone who is knowing what they are doing will know, what to do (wow - obviously...). Everyone else should get some help. 1. Remove the cover from the PSU 2. Remove the solder pins holding the silver parts of the PSU together, remove the tape as well. 3. De-Solder the AC-in and DC-Out wires / pins. Remove the AC jack. 4. Solder wires to the AC and DC site of the PSU. You are done converting the PSU. Please don't re-use the IEC connector from the PSU - use a proper one to mount on the printers chassi Drill 4 holes in the frame to mount the PSU to the inside of the printer. To align these holes with the PSU holes put the "naked" PSU on top of the frame and attach the part "PSU cover AC side" temporarly. The PSU Cover should not be flush with the bottom of the steel panel. Offset it about 10mm, otherwise the bottom of the PSU-Cover will be colliding with the bottom part of the frame. To attach the PSU to the frame glue the "PSU nut spacer" with an M3 nut to the PSUs PCB. Mount the 60x60mm fan to the PSU cover AC side using self-tapping screws. Than put both PSU covers onto it, route the cables through the big holes on the top site of the printed parts and screw it against the frame using 4 M3x14 screws.