From the start of the project, it was pretty apparent the scavenged z axis was not designed for vertical motion and would easily fall under the weight of is own extruder. A bowden cable was the ready made solution, and rather than investigating the potential for polyethylene tubing I opted for the standard teflon setup. Most likely this would not be used in a scavenger society, yes. It turned out the teflon tubing I ordered was much larger in diameter than those found in most printers, but as I discovered it never made much a difference. Whats more, friction with a tube this large has never yet been a problem. This finding gives me hope for the potential in the more common polyethylene tubing you can find in any hardware store, though it may be a while before I care to give it a shot.
But that’s an aside. Problems at this point were becoming apparent with the bakelite isolator and a replacement was needed. Since I was already putting the bowden cable to use, I figured I might use it to my advantage. My idea was to incorporate the bowden cable into the nozzle itself. The teflon tubing was not only self lubricating, but was also well suited to high temperature applications. The diameter of my setup would not be able to guide the filament much, but a second tube of teflon I had used for nozzle lining would work to that end.
With no need for an isolator, I would then only need the heat block and nozzle. Brass acorn nuts are already frequently used for the nozzle and would be available in any hardware store, so as far as I was concerned that part was taken care of. This would mean the only problem really was in affixing the acorn nut to the isolator using only common, ready made parts. A 1/8″ pipe fitting was well suited for that, and as I found it fit okay against a 5/16″ acorn nut. As with the previous hot end, a 1/32″ or ~0.8mm hole was drilled through the acorn nut. This was chosen as it was the smallest drill bit I could find in local hardware stores, and I imagine any smaller drill bit would likely get lost or broken in the event society wasn’t around to make new ones.
Shown here is the resulting hot end, at work printing a fan cover for the one I had scavenged from an old computer.