Revised MGN12H Carriage for BMG and BLTouch with RJ45 mounts, "Over the Top" Style

thingiverse

There is a new version of this carriage at https://www.thingiverse.com/thing:3615464 AND an even newer one at https://www.thingiverse.com/thing:3688067 I highly recommend the newest version for better rigidity and simpler printing and assembly! This older version remains available for reference.  _________________________________________________________________ _____ This carriage is a revised design based on the previous model, https://www.thingiverse.com/thing:3504020, "Carriage for BMG and BLTouch with Duct and RJ45 mounts, Over the Top Style". A user requested that it be compatible with thed0ct0r's "E3D V6 improved fan adapter with modded Prusa MK3 Layer Cooling" (https://www.thingiverse.com/thing:2769783), so I updated the design to accommodate this cooling system. The part cooling duct is fully height adjustable, allowing for use with V6 or Volcano hot ends and easy trimming of heights. I modified thed0ct0r's basic design, "Adjustable E3D V6 impr. fan adapter and modded Prusa MK3 Layer Cooling", https://www.thingiverse.com/thing:3512817 . The assembly is shown in some photos above, but only the carriage and BLTouch mount parts are included here. For the cooling system, download one of the mentioned designs or use the basic E3D V6 fan holder for the heatsink if not needed or wanted. _____ This design is intended for a Folgertech FT-5, but may also work on other printers that use an MG12H slider on a 2020 bar. It prioritizes: 1) keeping the nozzle close to the MG12H slider to minimize bearing tip effects; 2) including a BLTouch mount adjustable in height with guides on the slider; and 4) incorporating a mount for an RJ45 socket board to simplify wiring (using the MDFLY dual RJ45 board w/screw terminals): https://www.amazon.com/gp/product/B01KHMFH1M/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1 The carriage has been tested and works well with the adjustable fan adapter mentioned above. I modified the "A_Plate" part for a different nut location to make BLTouch height adjustment easier with a Volcano. Note: A broken trace on my MDFLY RJ45 adaptor board took some time to troubleshoot, so it's recommended to check continuity from screw terminals to RJ45 connectors before wiring and mounting. The "Over the Top" mounting is used because I prefer having the nozzle closer to the slider bearings, avoiding multiple inches of hanging down with normal motor and extruder placement below the 2020 bar. This design attempts to combine tight minimum-lever placement with the BMG's dual gear extruder. However, this causes a new difficulty: on the FT-5, the bed won't reach up to the nozzle! The nozzle sits only 10mm below the 2020 bar. To fix this, the bed needs to be raised about 48mm from the melamine bed platform with standard V6, or about 40mm with a Volcano. This can be done with some additional parts: https://www.thingiverse.com/thing:3518065 You'll also need to remove cable chains, which I consider a benefit as they're generally useless. Instead, spiral wrap the cables and feed them from the top/back side of the chassis for a cleaner and more open look. The carriage is set up for a short NEMA 17 motor (part number 17HS10-0704S, but should also work with the smaller pancake). A spacer is included that can be placed behind the motor to clamp it securely to the assembly, making it even more rigid.