Bondtech BMG for the Cocoon Create Touch by dkselw

Last crawled date: 4 years, 1 month ago

Geared Bondtech extruder for the Cocoon Create Touch/ Wanhao I3 Plus.
This extruder uses the existing heatbreak, in my case the Micro Swiss all metal heatbreak. I wanted to try the geared Bondtech drive, but did not want to have to purchase another heatbreak, as I had already installed the Micro Swiss all metal heatbreak.
I used this https://www.thingiverse.com/thing:2669164 for the model of the existing printer.
The Bondtech dimensions and clearances were measured using models from here https://github.com/BondtechAB/Bondtech_Prusa_i3/tree/master/CAD-Files
Hardware
I used the gears and bearings from inside a Bondtech BMG extruder.
Zaribo Pancake Extruder Motor https://zaribo.com/electronics/126-zaribo-pancake-motor-by-ldo.html . I believe this is the same as the LDO-42STH25-1404MAC . The Stepperonline 17HS10-0704S should also work and is recommended for other geared extruders, such as the "Bunny and Bear Geared MK3 Extruder".
3mm thick aluminium spacer for the heatsink. Trace around the side of the heatbreak cooling block for dimensions.
PC4-M10 Straight Pneumatic Fitting (supposed to have a M10 thread, but mine ended up being 1/8 NPT).
4mm OD Capricorn Bowden PTFE Tubing for between the heatbreak and just below the drive gears.
4mm OD PTFE for the reverse bowden tubing.
1 x PEM IUBB-M3-1 heat-set insert. I used the Lulzbot Heat-Set Insert Tapered, M3-0.5mm Internal Thread, 3.8mm L. A longer heat-set insert would be better.
The filament path in the model is 1.75mm diameter. This will need to be drilled out to 2mm after printing.
I ended up having to use a reamer to get the bearings to fit nicely as my printer was printing the holes too small.
Use a 4mm drill to clean out the holes for the PTFE tubing.
Use a 4.2mm drill to clean the hole before inserting the heat-set insert.
Depending on how well your existing printer is calibrated, you may need to drill out other holes to size as required.
I did not have screws long enough to go all the way through the fan, extruder and spacer to the motor, so I used the existing screws to attach the heatsink to the spacer, extruder and the motor. The fan was then attached to the heatsink with short 3mm screws.
If you use the hinge pivot shaft from the Bondtech extruder, you will need to shorten it so that it does not protude past the outside face of the case. I used a piece of 3mm shaft from an old CDROM drive.
The white Bondtech gear protrudes out the back of the extruder. Check the clearance between the gear and the x-axis bearing screws. You may need to slide the heatbreak towards the front along the sheet metal bracket and/or shorten the x-axis screw. Mine had just over 1mm clearance without moving anything.
If you use the specified pancake stepper, you will loose about 5mm of the X travel. If you use the existing stepper, a bit more.
I printed the parts using the amf files, not the stl files.
Slicer settings:
0.2mm layer height
20% Gyroid infill
10 layers top and bottom
5 perimeters