UPDATE 8/13: I have added a single fan duct that lowers the duct by 1mm to reduce blowing on the heatblock. I have also reduced the front hole height. If you use a sock there will still be air blown on some of the sock but it still performs well on overhangs, only slightly worse than the dual fan. I may keep using this instead of the dual fan as it is much quieter and reduces the overall extruder weight. If you print materials that require high temps and little or no fan, such as ABS, ASA, PC, and Nylon, you need to temporarily remove this duct as its way too close to the heatblock and will warp.
UPDATE 7/28: I have added v3 of the Dual Fan duct that uses the ducts from pvnencak's design as they are much better shaped for directing air under the nozzle. This will reduce the amount of air hitting the silicone sock if you use one. I tried to use the fan placement of that design but the E motor prevents it so I just used the ducts and it has made a notable cooling difference as well as cleaned up a lot of the design.
UPDATE 7/17: I have back-ported the v3.5 wire routing changes to v2 as it may cause X-axis alignment issues. I realize not everyone wants to extend the PTFE tube like v3.5 so I have uploaded v2.1 with only those changes. I have also updated the dual fan duct to v2.1 to extend the left screw hole to allow tightening without breaking the mount.
UPDATE 7/13: I have uploaded v3.5 of the extruder body with a few more changes. This has been well tested to work with an MMU2 and I have uploaded the cooling tube settings as an image. I will likely use this version for another month before making any more updates if anything is needed.
- Changed the wire routing cover above the 40mm fan so that the extruder lines up correctly with the motor x-end. This still passes calibration without any issues.
- Minor geometry fixes
- Added a new PTFE cutting jig with 17 and 28mm sides. You can easily push out the cut tubes using a M3 allen key.
UPDATE 7/7: I have added a V3 of the Body files with the following changes.
- Extended the lower PTFE tube up so that its 28mm now, this should create a smoother filament path, in particular for the MMU2S version. This will require some tube trimming (less than 0.5mm) where the extruder motor shaft enters the body.
- Added an upper 17mm PTFE tube to the MMU2S version to reduce filament path friction
- V3.2 I added reinforcement on top of the lower PTFE tube where the stepper shaft enters as the area was too thin and failing. This still provides ample space for the BMG drive gear.
EDIT 7/18: Make sure you print the following missing items from one of the remix sources before you install your extruder if you don't already have them! I didn't want to upload files that I made no changes to as they are completely someone else's work.
I wanted to make a Mosquito Hotend compatible BMG extruder which would pass normal MK3S firmware calibration and require no hotend mounting adapter. I used almost all of the extruders that are attached as remix sources to some extent and decided to make a mega combo extruder. I have been really lazy about uploading this so it has over a month of testing behind it, no issues at all to report. Note that I am using the Mosquito Magnum hotend in my build but this would work just fine with the regular Mosquito hotend as well since they have identical dimensions.
- Passes stock MK3S firmware calibration without any tricks meaning you maintain the full 210mm Z height
- Simple Mosquito Hotend mounting without an adapter or groove mount that allows it to be installed and removed without disassembling the extruder (only the 40mm fan needs to be removed)
- Full Bondtech BMG support
- MK3S or MMU2S IR sensor mounting support
- Stock MK3S fan duct or any standard MK3S duct support
- Bear extruder PINDA mount (super strong)
- Standard Bondtech Prusa BMG Carriage mounting holes so the MMU2S version will work with any bondtech prusa extruder x-carriage
- Designed to use the universal Bunny x-carriage for MK3S version (but not needed for MMU2S version)
- Special Dual Fan duct designed specifically for this extruder (not needed)
- Full Mosquito Hotend silicone sock support
- Use the stock 40mm extruder fan, it provides sufficient cooling for the mosquito magnum
I suggest following more detailed instructions from any prusa bmg extruder in the remix sources. But here are some basic guidelines when installing this:
- Prior to printing decide whether you need the MK3S body with the upper IR sensor space or a direct filament path with the MMU2 version. All screws and nuts used in this design are M3 except the hotend mounting screws which use M2.5 included with the Mosquito kit.
- I used PETG for my initial design tests but settled on PC-ABS (Protopasta) for the final design due to high temp resistance, high strength, and lower density without the brittleness of full Polycarbonate. If you don't print hotter than 250C then no need to print in anything more than PETG.
- Make sure to ADD support enforcers or manual supports to the idler lever area of the extruder body since its a serious overhang. No other part or area needs supports in this design.
- Pre-thread all screw holes such as the top sensor cover, fan and fan duct mounting holes. I suggest drilling out the filament path in the body with a 2mm or 5/64" drill bit. You should also trim open the extruder cover and body long screw holes.
- Add all square nuts to the cover (4) and body (3). If you go with the dual fan duct there are 2 needed there as well. I recommend using some tac or other removable adhesive on the square nuts to hold them in place if the holes are slightly too loose.
- There is a diagonal cut in the pinda probe mount that you need to cut through, this is particularly important if you use the bunny universal carriage as the pinda holder will hit the X-end if it is not cut.
- Use a 6mm M3 screw for the angled left mounting hole for the Extruder motor, 8mm works too but is much harder to angle in. 8mm works perfectly for the right hole.
- If you use the Bunny Universal Carriage then you will need to print the spacer(1) and lower plate as the extruder cover needs screws inserted from the back of the printer. The carriage is also a bit thinner so the spacer allows you to use a 50mm screw in the bottom left without hitting the motor.
- Use 45mm screws for the top and right extruder mounting holes.
- The side fan mounting holes are extended to allow 16mm screws, the lower right screw hole extends into the fan duct square nut so use a 18mm screw there.
- The mosquito hotend mounting holes use the M2.5 screws that come with the hotend in black, 2 are longer and 2 are shorter. If you can acquire two 20mm M2.5 screws then you only need to screw them in from the PINDA side, so you no longer need to remove the 40mm fan to remove the hotend!
- Use a 13.25mm PTFE tube above the hotend in v2.1. Use a 28mm tube for v3.5 and an additional 17mm tube for the MMU2S version. The PTFE cutting jig has been uploaded to make exact sized tubes for v3.5. Make sure to trim open the top (widen the hole) of both ptfe tubes with a blade to facilitate filament loading.
- In v3.5 you have to cut off a tiny piece (<0.5mm) of the lower ptfe tube where the extruder motor drive shaft enters the body. Use a razor blade or xacto knife to follow the curvature of the hole and slice a piece of the tube. See attached pictures for details.
- Grab a sensor cover and idler lever from any of the remix sources.
- If you use the Dual Fan duct, the center mounting hole uses a 10mm screw and the right arm mount uses an 8mm screw. The arm screw goes in from the back of the extruder cover where it has the hex nut impression. This was done to maintain compatibility with the stock duct.
- Make sure to set your e-steps correctly via gcode for the BMG gear ratio:
Standard 1.8 degree motor - M92 E830, M500
0.9 degree motor - M305 E16, M92 E830, M500
I own no rights to any of these designs, I merely combined a lot of them and made some tweaks to accommodate screws and nuts. I am NOT a designer or engineer, simply a hobby enthusiast who dabbles in upgrades.
All thanks and credit goes to the original designers:
Grégoire Saunier - Bear Extruder
Guy Kuo - Bunny Science
Jerry Stegenga - MK3S Mosquito Extruder
Juan Puchol - Mosquito Bondtech BMG Extruder
Marco Zambon - Bondtech BMG FDM Extruder
Stefan Weber - Mosquito Bondtech BMG Extruder
Jonathan R Swift - Dual Fan for Prusa Extruders