Wilson X carriage
I posted this on Thingiverse a while ago, but it has worked so well for me that I feel I should write it up properly.
The Prusa i3 design has worked very well for me over the 3 years that I have been 3D printing stuff, but there's one area which I thought could use some improvement. That's the x carriage, the thing that actually holds the hotend and moves it around. On my Folgertech i3 clone as designed, the extruder motor is mounted onto the front of the x-carriage, and the hotend and extruder mounts on the front of the motor. This is not ideal, the main problem being that the all of these parts are reasonably heavy, and being cantilevered out like this all on one side puts a significant torque on the x-axis rails, enough to bend them slightly (they are rather springy). Because the hotend is placed all the way out at the end of this cantilever, it experiences the greatest effect of this deflection. Note that the rods bend more when the x-carriage is in the middle, and as it approaches the supports of the rods at either end, the bending goes away. The end result of this is that the hotend sags as it traverses the x-axis.
Additionally, I upgraded my hotend to an e3dv6, the hobbiest standard for 3D printers. It's a tried and true design that has proven itself to work well on all sorts of plastics. However, it is a bit longer than the Folgertech extruder. When I found that some filaments were requiring too much force to push through the all-metal hotend, I upgraded to a BMG extruder clone. The BMG extruder design is also an excellently designed product, with properly shaped drive wheels that grip the filament better than a cylindrical knob and a passive roller, which is used in the cheap extruder that comes with many printers. The BMG drive wheels are even geared together, to provide a dual drive action pushing the filament on both sides. The BMG extruder is also geared down to the motor, requiring less torque at the motor shaft, and potentially more resolution as the motor is making more rotations.
More to come.
The TL;DR version of my design
- Placed motor on rear of X carriage to balance weight front-back
- Heavy components in the center, light ones on the outside
- Geared BMG extruder, for increased filament grip, and less motor torque required
- Brought hotend closer towards the X-axis, minimizing effects on nozzle height from X-axis twisting
- Solid metal filament guide path, adding rigidity and reducing slop in the filament positioning.
- Extra mount holes for accessories like bed leveling sensors.
- Centrifugal fan, providing greater air flow at higher pressure vs axial fan.