While doing some experiments running my extruder at different speeds and temperatures, I managed to run it at too low a temperature such that it forced the PTFE barrel out of its clamp. That broke off one of the heater wires under the JB Weld. Fortunately I was able to dig out the end of the nichrome and reconnect it. I soldered the joint but that is not the best idea as solder melts at 183°C and I am running my barrel at about 200°C. The heater gets a bit hotter than that. Presumably molten solder is still a good conductor. The ideal way to make the connection would be with a miniature barrel crimp but I don't know if they exist. Here it is repaired :-
Clamping a very slippery plastic rod with a clamp made out of a slightly less slippery plastic is probably not the best design.
I seem to spend as much time stripping down and rebuilding my extruder as I do running it. Looking on the bright side at least the thermistor didn't fall off again despite some rough treatment. Here it is all back together again and working :-
I once made my own inline connection in a tight spot by cutting off and discarding the blade from a spade connector, and crimping both wires together in the collar piece that remained. The oven is still working a few years later.
ReplyDeleteGood idea, I will try that when I make my next one.
ReplyDelete"Clamping a very slippery plastic rod with a clamp made out of a slightly less slippery plastic is probably not the best design."
ReplyDeleteYup, that aspect of the Mk II design was the first thing I changed when I designed the Mk 1 AEM extruder. While a friction grip on what is arguably the slipperiest polymer out there, viz, PTFE might work for CAPA it's looking for trouble when you need to create higher extruder barrel pressures.