Manta MINI Bear 2.1

***NOTE: This build departs from the original vision for the Bear project and does not reuse many of the electrical components of the Prusa Mini. If you would like to retain stock Prusa MINI firmware, mainboard, screen, power supply, and slicer settings, please refer to Tomson's work. ***

The Story:

I wanted to upgrade my Prusa Mini and found the Mini Bear project started by Pear3D and carried on by 3DMamsih, Tomson, and others. The original design from Pear3D was not fully compatible with the Blurolls Mini Bear Upgrade Kit on Aliexpress so I modified the official Bear 2.1 release to fit the smaller frame. 

During tear down of my official Prusa Mini, I broke my buddy board. Instead of doing the sensible thing and buying a new buddy board, I decided to buy a Manta M4P so I could run Klipper/KlipperScreen and tune the firmware to the new machine more easily. The new control board required a new power supply, power inlet, fans, and screen. This build replaces most components from the Original Prusa Mini and is NOT a conversion. It is less expensive to buy a Prusa MINI heat bed and the extra smooth rods rather than sacrifice a working Prusa Mini. 

The Manta MINI Bear project is on GitHub. You'll find, firmware, slicer settings and a wiring guide. This project is fully open source, including the CAD software, slicer, and printers used to develop it.

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Sourcing Guide:  

Option 1 (already have a Prusa MINI to sacrifice)

• Prusa Mini (The Sacrifice)
• Prusa Mini Motor: https://www.printedsolid.com/products/original-prusa-stepper-motor-z-axis
• Mini Bear Frame Kit: Aliexpress
  •  Extrusions--220mm*1,350mm*2,300mm*2,285mm*2
  • 2020 joint plate--10pcs
  • angle corner--4pcs
  • bear fasteners kit
  • LM8UU bearings--5pcs
  • 310mm 8mm ID smooth rods--2pcs
  • Z  310mm TR8*4 leading screws motor
  • Dual Z motor V cables

Option 2 (Scratch Build [recommended])

• Mini Bear Frame Kit: Aliexpress
  •  Extrusions--220mm*1,350mm*2,300mm*2,285mm*2
  • 2020 joint plate--10pcs
  • angle corner--4pcs
  • bear fasteners kit
  • LM8UU bearings--5pcs
  • 310mm 8mm ID smooth rods--2pcs
  • Z  310mm TR8*4 leading screws motor
  • Dual Z motor V cables
  • extra 5PCS LM8UU bearings
  • Y carriage
  • Prusa mini motors kit(1 X/Y motor, 1Z motor, E motor)
• Mini heat plate: Link
• Mini flex plate: Link
• Mini Y axis rods - 2pcs: Link
• Mini Y carriage bearing clips: Link
• superPINDA: Link

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Other components: 

• SKR Extension Cable Kit: https://www.printedsolid.com/products/skr-extend-cable-kit
• GDSTIME 4010 hotend fan: https://a.co/d/8Xqg1KY
• GDSTiME 5015 Part Cooling Fan: https://a.co/d/59xCshC 
• Fan Extension cables: https://a.co/d/gPuEJPU 
• Nema14 Sherpa Mini Motor: https://amzn.to/4271kFB
• Extruder Gear Kit: https://amzn.to/3l9c6KO 
• LM8UU bearings - 12pcs: https://amzn.to/3ZJVFDQ - (optional extras)
• Heatset Inserts: https://amzn.to/3LjvMWW
• USB-C Flat/Slim Cable 20-50cm: https://amzn.to/3lbkyt8 - (20cm is barely long enough 50cm is way too long)
• HDMI Flat/Slim Cable 20-50cm: https://amzn.to/3Jyki0x - (20cm is barely long enough 50cm is way too long)
• BTT Manta M4P Board: https://amzn.to/3JC4GZV
• BTT CB1 + Heatsink: https://amzn.to/3mRkvCZ
• BTT HDMI 5 Screen: https://amzn.to/3LkQy8T
• BTT TMC2209 Stepper Drivers - 4pcs: https://amzn.to/3ZQPwWE
• Meanwell LRS-150-24: https://amzn.to/3yzCssv
• IEC320 Power Inlet: https://amzn.to/3Fl9wIE 
• M3 Screw Assortment: https://amzn.to/3JylfpD
• GT2 6mm Belt: https://amzn.to/3ZYLPh0 
• Nylon filament for cable support: https://a.co/d/4lLNyUb 
• 16awg wire: https://a.co/d/6c2nmfT 
• Ferules: https://a.co/d/at6Qzmv 
• Fork Connectors: https://a.co/d/3gTptHV 
• E3D Revo Voron (24v): https://www.printedsolid.com/products/e3d-revo-voron?variant=40112289874005 
• ½" Cable Wrap: https://a.co/d/5FsfY4d 

Tools: 

• Soldering Iron: https://a.co/d/0kgInuX 
• PH2 Phillips Head screw driver - for PSU terminals
• 2.5mm Flat head mini screw driver - for control board terminals
• Metric Hex Wrench set: https://a.co/d/eyAppt3 
• Crimping Tool: https://a.co/d/9wbbjsO

NOTE: These are not affiliate links. Amazon rejected my application. Many components can be found on other websites and I encourage shopping around for parts that are affordable and located near you. Where possible, try to buy authentic OEM parts. 

WARNING: This build will require preparing a cable to extend from the PSU to the Mainboard. I am self taught, therefore not trained or certified in electrical work. The wire choice suggested is what I used on this and other printer builds. I have not experienced any fires yet. 

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Printing Notes:

Prusa Research and Greg Saun recommend printing their components in PETG. I printed everything in Polymaker ASA using the Voron recommend print settings. The only issue I had was fitting the 8mm rods into their slots. I fixed this by using an 8mm drill bit to clean up the slots.

Supports: The only part that needs any support material is the LRS-150-24-mount-bottom. 

Spool Holder: I like my spool holder attached to the frame with a reverse bowden. Steve Peterson made a good one so I have been using his on all my printers. You can find the spool holder base and reverse bowden mount here. You can find the spool holder Arm here.

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Build Notes:

The aluminum extrusions do not follow the same sizing as the official bear build. Please reference the attached .blend file for positioning. 

The X, Y, and Z axes along with the tool head wiring follow closely with the Bear 2.1 manuals. Reference these for assembling the motion components of the printer. 

Mounting locations for threaded inserts are pretty easy to spot. Look for small cylindrical holes in the plastic parts that don't seem to go anywhere. These are where threaded inserts should go. 

I placed threaded inserts in the .blend file everywhere they are needed. These can be found using the part navigator in the upper right of the display. Alternatively, you can click on any object and press “H” to hide and “Alt+H” to unhide. To rotate view, click and hold the middle mouse button. To pan view, press and hold “Shift” while holding the middle mouse button.

I have not documented all of the screws or screw lengths needed for this build. The screws kit provided in the frame kit provides all the needed M5 screws. An assorted set of M3 screws should provide the remaining screws needed. 

Sherpa Micro: I did not include any parts or build instructions for the Sherpa Micro. Please reference the official release for more information on sourcing and building the extruder. You may be able to source a prebuilt sherpa micro. 

Sherpa Mini: My toolhead is not compatible with the Shrepa Mini. If you would prefer to use a sherpa mini, please reference Adrian Dobre's original tool head (here). 

Wide Bezel: This part is included for users who do not want or are unable to source the specified ribbon cables. The HDMI and USB-C cables must be installed in the screen before the bezel is secured. Wires can be routed through the back of the control box. 

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Wiring notes are provided on GitHub. 

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Firmware/Slicer:

This printer runs on Klipper firmware using the BTT Manta M4P and CB1 control board combo. 

I opted to install the Debian minimal kernel (Here) and then use the famous Klipper Installation And Update Helper (KIAUH) to install Klipper, Mainsail, and KlipperScreen. 

Please consider installing Klipper before inserting the M4P into the the control box. It is possible to insert and remove the microSD card while the board is in place but it is not fun.

You can find my config files here. 

You can use my PLA slicer profile to start (here) or simply modify the stock PrusaSlicer Prusa MINI profiles to match. 

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Source File:

I chose to do my design work in Blender. This is not engineering software, but it is free and open source. Included in the download, you'll find the .Blend file that I used to to develop this printer. Please feel free to design, mod, or change your copy of this file. 

NOTE: Parts exported from this file must be scaled up 1000% in the slicer to be useable. After scaling, part accuracy is pretty reliable. 

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Credits:

Josef Prusa and the Prusa Research team for hardware development on Prusa MK3 and Prusa MINI, and for PrusaSlicer. These resources made this build possible. 

Blender.org for the excellent design software. 

Big Tree Tech for the parts, step files, and information needed to develop the printer. 

Greg Saun for the Bear 2.1 motion components. 

Tomson for the extrusion end caps.

3DP-Mamsih for the build helper jig.

Adrian Dobre for the tool head. 

Annex Engineering for the Sherpa Micro extruder.

Dan Borio and Chris Warkocki for hardware consultation.

Hymness1 (Patrice) for Klipper macros. 

The Twitter 3DP community for inspiration and feedback.

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Update Jun 13, 2023: Added BOM to Github