Bowden Blowout!

Had my first Bowden tube failure the other day the tube became detached at the extruder motor end due to internal pressure I guess, and in my frenzy to get it fixed I broke my hot end’s heat resistor, unfortunately I had no stock of these resistors but I did have the old Darwin hot end that I had retro fitted with a new heater block purchased on eBay (it used to heat using a coil of nichrome wire) I had already fitted my only spare heat resistor to this hot end so I thought whilst I was waiting for the replacement resistors to arrive in the post I would fit the old Darwin hot end to the Prusa and see what it could do.

After much fiddling around I managed to get this “working” the quality was poor compared to the Parcan hot end as the nozzle diameter is approx. 0.9mm on this old hot end, also this hot end has a brass hexnut style nozzle so it would be fairly easy to replace the hexnut with one with a smaller nozzle hole, this was all done so that I could test the possibility of reusing this modified Darwin style hot end on the Darwin once I get it back up and running.

In fact I was actually in the middle of printing a new X carriage for the Darwin when it broke, the new X carriage is based on the 10mm lm10uu linier baring derivative of RichRaps great Quick-change X carriage (ref).

I had already printed one of these 10mm Quick-change X carriages but it turned out that the Darwin has 42mm X rod spacing unlike the Prusa which has 50mm X carriage rod spacing, so I loaded Sketchup and modified the X carriage (virtually) chopping 8mm out of the center and bringing the 2 halves back together and exporting as STL.

Printed this modified Quick-change X carriage using the old Darwin hot end (with retrofitted heater block) this worked remarkably well (well at least better than I had expected) and after a few hours of fiddling the Darwin is moving again.