Dual extrusion systems for 3D printers have been around for quite a few years, but the additional cost, complexity, and hassle of printing with them have kept them off the workbenches of most hackers. [Jón Schone] from Proper Printing has now thrown his own hat in the ring, with a custom dual extrusion rocker system that can swap extruders without any additional actuators.
The two extruders are mounted on a spring-loaded rocker mechanism, which holds the inactive extruder up and away from the printing surface. Extruders are swapped by moving the carriage to either end of the x-axis, where the v-wheel rolls a ramp and pops the rocker over, putting the new extruder in the center line of the carriage. There are 3 wheels at the top of the carriage, but only two are in contact with the rail at any time. While this system is more complex than simply mounting two extruders side-by-side, it reduces the chances of the inactive nozzle oozing onto the parts or scraping across the surface. The height of each extruder can be adjusted with a screw, and any horizontal offset between the nozzles is checked with a calibration procedure and corrected in the firmware. See the full video after the break.
While we’re big believers in 3D printing here at Hackaday, there’s no denying that some things just aren’t meant to be printed. For example, most of us would agree that it’s not the first choice for making rims for a passenger car. We imagine that [Jón Schone] from Proper Printing probably feels the same way, but that didn’t stop him from trying to do it anyway.
A couple of months ago [Jón] got a test subject in the form of an older Mercedes with 19-inch rims. The first two challenges are bed size and warping, so he modified a Creality CR10 S5 with a heated chamber capable of reaching 70 °C to reduce warping with the ABS filament he intended to use. Another challenge is the amount of filament required for the print, especially since [Jón] wasn’t keen on babysitting the machine to replace the spool every so often. His attempt at building a filament joiner ultimately didn’t work out, so in the end he simply sourced the filament in bulk size rolls.
Eventually [Jón] managed to print a complete rim in two halves, bolted together around its circumference. Unfortunately, even with the heated chamber, the parts still warped all around the edges. This left a gap at the seam, but to fit a tubeless tire, the rim had to be airtight. So the entire inside surface was painted to close any small gaps, and the larger gaps were filled with sealant.
In the end it was still unable to hold pressure with a tire mounted, so it was test fitted to the car just to see if it would carry the weight. This test also failed, splitting on the thinnest part of the rim. [Jón] has headed back to the drawing board to try again in 2021. We probably would have moved on by now, but you have to admire his tenacity. We hope to see success in the new year.