Nothing good lasts forever

Hot (or rather, not so hot) on the heels of boasting of my many successful prints comes a tale of woe and sorrow! Woe! Sorrow! Or at least some technical problems.

While printing a faucet filter tool of presumably the right size for ours faucets (I was too lazy to measure), my white filament ran out. Supposedly, the printer should handle this nicely, running an unload procedure immediately. For whatever reason, it didn't, just letting the filament continue through until it was past the drive and thus the point of no return. Apparently, but I didn't know at the time, it's feasible to just feed in more filament immediately, but I tried re-running unload, then pushing the filament piece further down. To no avail, it was stuck.

Opening the side (which hinges up nicely), I found a lot of white debris (it had ground down the end of the filament). After vacuuming most of it up, this was the sight that greeted me:

Taking a closer look with my proper camera, it was clear that the filament sat in a PTFE tube and wasn't a giant blob or anything.

So I tried pushing some more, at higher temperatures, but it wasn't budging. Eventually, I had to take the hotend assembly out, and since I'd probably need to take out the nozzle anyway (one page suggested removing the nozzle and then heating), I would swap to my 0.8mm MegaNozzle shown below (banana for scale):

After getting a set of inverted hex bits (very useful!), it was easy enough to unscrew the nozzle, but that didn't help with the blockage. Fortunately for me, they had designed the whole thing so that taking out the hotend is relatively easy, and I was able to unscrew the heatsink and heatblock. They advice against unscrewing the heatblock, but I didn't see how to avoid it, since it's not really accessible. Anyway, with that out, I was able to heat it in the oven and carefully puuuull out the filament until it went "plop" and popped out. This was essentially the classic cold pull, though possibly a bit too cold due to not having the right tools right at hand at first. The PTFE tube needed replacement, but fortunately my kit came with two spares - how prescient!

So I reassemble the whole thing and run a test without filament - after all, I need a nozzle in there first, which requires 285C. Alas, the heating is bad - it heats up, but very slowly, at 100C about 1C per second. I didn't let it run for long enough to get up to full temperature, it took over a minute to get to 135C. To check that it wasn't the thermistor misreading it, I poked an old PLA print at the heat block, but it only deformed slightly, so it definitely wasn't doing runaway heating. That's something at least, overheating could be quite dangerous. But I'm still stuck with bad heating. I double-checked the wiring in the board, and the resistances and voltage were correct. So either there's a loose wiring in the heatblock end, or... something else.

It moves! It lives!

Having mostly dealt with the problems from last post (Flimsy wiring? Get the right jacks. Overheating driver? attach driver directly to frame. Loose coupling? Tie down coupling with hose tightener (which required dremelling a hole for the screw to rotate through), I have been able to make both X and Y stages move! The whole setup also looks much tidier now.

The stages can move for a seemingly arbitrarily long time, but they still overheat if standing still for about 30 seconds. Have to find a solution for that. I don't know if thermal paste will change much when I've already bolted them tightly together.

Major problem: Both stages have a tendency to switch between running smoothly and getting stuck, depending on exactly how the rod is aligned. I'm guessing the guiding bolt is a little loose, and can change between perfectly aligned with the rod and not quite perfectly aligned.

After cutting off superfluous edges and cutting a notch on the Y stage for the tube tightener screws, I have about 11x16 cm of writeable area. Not a lot, but enough for tests and for a RepRap, should I go that way (requires a plastic extruder, though. First some 2D tests!)

Softwarily, I have refactored the little test program to where I have two functions: move(dir, axis, len) and pauseSeconds(seconds). The move() functions is almost calibrated to move in cm.

For playing around, I am tempted to hook up three three-way switches so each axis can be controlled independently. Or maybe get a mini joystick controller:)