The geared extruder reuses metal gears from a DC motor gearbox in order to increase torque and precision. The printed frame holds brass bushings drilled out of a brass profile, which hold the rods with gears.
The glass extruder prototypes are borosilicate glass tubes heated while being rotated on a flame in order to close them. As the glass softens they close due to surface tension. Once closed they are sanded until a suitable hole
diameter is achieved.
As one might imagine, they are quite fragile. Since the glass is less thermally conductive it can be serve both as a hot and cold end, but it lowers the maximum printing speed.
Once cooled the filament can be removed from the tube as it doesn’t stick, atleast not for the first few prints. After that, some residue collects which makes it stick.
Another big problem is that the glass has much less thermal expansion than the heating block, so it tends to get detached.
Although the prototype glass extruder worked, it wasn’t reliable and I haven’t had the proper tools to keep development, so I abandoned it.
The gearbox works fine though.
The extruder won the second place at the mini maker faire in Trieste, 2016.