A rework in progress

After the last repairs, I got sufficiently annoyed by the mess of wires around the extruder. In particular, having the extruder motor wiring as well as the fan wiring bypass the break-out PCB entirely made for a tangle as well as some rather unstable connections.

Extra wiring can be seen on the far side of the ribbon cable.

 I acquired new ribbon cable, D-Sub connectors (3 of them, just in case), and went to work. I only had to discard one of the D-Subs, and this time made sure to thoroughly test the connections. I cut the cables back to make for a neater lineup at the controller, and labelled the parts with Dymo labels this time (plastic, not paper, for fire safety).

Now having all this set up, the tests gave some rather disappointing results. For one, the thermistor and heater are connected, despite the instructions declaring - in boldface - that they shouldn't be. And indeed, the thermistor insists that my room is over 100C, which I am sure I would have noticed. The X motor and endstop work, but the extruder motor is making a strange faint clicking noise, even when doing nothing. Neither fan activates. This might take a bit to clean up - I even suspect the PCB itself has issues. The hour of remaking the PCB to include the proximity sensor draws near - and finally the otherwise unused cable #5 could come to the fore.

I'm rather concerned about the heater/thermistor connection, though, as it manifests on the controller board even when the heater is disconnected.

Update: The PCB appears to perform its functions exactly as advertised WRT the heater, thermistor, and motor. Disconnecting the ribbon cables from the controller board shows there's a ~1K connection from the lower HOTEND connector to the ETEMP connector.

Repairs

Following my disaster from last year, I tried to salvage what I could. For the extruder motor holder, I was able to set it on a thing with a hole and bash a hex wrench through it, popping out the stuck piece. The heat sink proved more problematic, though. I was hoping I could soften it in the oven and pull it out, but the spread-out part wouldn't budge. My next attempts were using increasingly hot oven temperatures to try to hammer it out from the other side. For this I needed something sturdy and heat-resistant I could set it in - after some searching, I noticed the steel pipe I recently got for sword swinging practice fit nicely, and could be set up in some of the drawer handles to stand upright. However, this mostly just squished the filament further together in one end. I eventually got some of it to melt out, but at this point I had bent the hex wrench, and while looking on the Internet for advice saw one important warning: Do not get the inside of the heat sink scratched! Well, I had just hammered a steel hex wrench into it several times, so at this point, rather than spending more time on trying to clean this, risking all manner of annoying problems in the future, I gave up and ordered a new one from e3d. Being the cheapskate I am, I had it shipped with Royal Mail, so I expect it'll arrive some time before New Year's.

I've considered the state of the ribbon cable and breakout PCB some more. Redesigning the PCB would be fun, but isn't really necessary at the moment. What I should do, however, is replace the cable with a fresh one, properly made. I will start by cutting a bit of extra length, attach the connectors, and test the connections before actually swapping anything out. I would like to have a few more wires around for extras, but the ribbon cable holders near the X end-stop don't have room for more. I'll just have to see if I could steal heat break fan power from the hotend itself and use wire 5 for probe signal.

Oops

Doing a new print this morning, the filament stripped not long after the start. Bother, said Pooh. But when I tried to do a cold pull, the filament snapped instead of coming out. That's a bad sign. Then I realized that thing I hadn't been hearing was the extruder fan not running since I had taken out Wire 5 yesterday. Turns out it is in use, just for permanent fanning. It would be better, methinks, to take that from the heater 12V, but that would require redoing the PCB.

In that case, I might as well redo it such that it more directly supports a proximity probe with voltage splitter as well, and get the cable fixed once and for all. This increases the work substantially, but would in the long run make the whole mess of cables be much nicer. And I rather like doing PCBs, the Fritzing app is quite good for that.

In the meanwhile, I'm going to clear out this probably blobbed-out piece of filament the hard way. I just hope it hasn't melted into some of the non-metal pieces, that could get hairy. It struck me that printing the extruder motor holder in a clear filament would make it a lot easier to see what goes on in there. But that's not for now, that holder is difficult to get right.

A quick search finds this already-existing breakout PCB with all manner of things.

Morning-after update: Took apart the hotend again. It's fucked. The e3d heatsink has a piece of filament stuck in it, blobbed out at the top. That can be heated and removed, I'm sure. Worse, a piece of the filament melted near the bottom of the extruder mount, and it might have fused too much to remove - I certainly haven't been able to just push out out from the far side.