Realized after taking off the nozzle for cleaning (without removing the filament first - oops!) that it's a 0.4 mm, not 0.5 mm like me previous one. No wonder the needle did no good for cleaning. Fortunately I have some 0.3 mm metal wire at hand, so I can clean it.
I adjusted Slic3r settings to have 2 skirts, 0.4 mm nozzle, and go at 50mm/s for edges, 60mm/s for infill, hopefully that will prevent the too-high backpressure.
...three-week break here due to general annoyance, business, vacation, and wanting to get better filament...
After talking with +Richard Jørgensen, I got a spool of Innofill filament, since I suspect my current filament of being dirty. He also prints PLA at 230-240, which seems rather high to me. He mentions a sweet smell when getting the temperature right, which I would have expected is actually the PLA starting to burn (or caramelize), but it works for him.
Last time I printed three cubes at different layer heights - or so I thought. They were all the same, for some reason Slic3r is remembering but then ignoring my settings changes, including then of course temperature settings. If I set the layer height on the command line, it does use it.
Dug into the settings problems. It all stems from my attempt to set 2 skirts. That required going into expert mode, in which each of the three parts of the settings can be read from a different file (which file is nowhere specified). Trying to use --load to specify a different file doesn't work too well, since any changes are still saved elsewhere. Using --load and --save just copies the settings. Used `find` to figure out where the files are (./Library/Application Support/Slic3r/print, of course) so I can specify the right one from Pronterface. Pronterface helpfully ignores the stderr output in their console, so I can't tell if the file is missing or corrupt or I gave an invalid option or what.
Slic3r's option file handling is also silly. There are three separate settings for option files, one for each part of settings, and they're remembered separately (somewhere). But they all contain the full settings, so using the wrong place will be silently ignored. Plus the simple mode doesn't use the same files as expert mode. In expert mode, the settings files are shown without the .ini extension, unless you specify the file on the command line (which you have to do to use it in simple mode), in which case the same file can appear with and without extension - or if you open the same config file twice, it can occur twice. Confusiorama!
It would appear that I have finally got my slic3r settings in sync with what actually slices, using /Users/lars/Applications/Slic3r.app/Contents/MacOS/slic3r $s --output $o --load "/Users/lars/Library/Application Support/Slic3r/print/Simple Mode.ini". At least it doesn't ignore the number of layers any more.
After some simple tests I should run a temperature tower. Just need a good way to set the right temperatures. It would be nice if STL had some way to indicate that, or at least to pass a comment through, but STL is an exceedingly primitive language (for better and for worse). Looks like I'll have to figure out the appropriate Z heights to insert temperature changes. Later.
Found part of my mounting problem. The diameter of the e3d part that gets mounted on is 12mm, but the holes in the extruder motor mount are 12 mm from center to center. So the screws are forced wide apart. Grr. Is nothing standardized around here? However, a bit of offset or angling is not going to make the filament catch, since the e3d has a nice slanted filament entry. It's just ugly and annoying and I get big gashes on the e3d mounting area from screwing into it.
Had to disassemble the hotend entirely to get the filament out. Here's the part I finally pulled, I think the dark marks are from rubbing against the side. Also notice the specks in there. Accumulated dirt or bad filament? Good question.
The blob on the left is also interesting. I suspect that's from where the heatbreak meets the heatsink (see below) if they're not screwed in well enough. Though I don't see much of a gap when peeking through it.
While fiddling with getting the filament out, my thermistor broke off one leg. Bother. I don't have a spare of the same kind, but I do have two spares of the old kind. Except (and I see that only after carefully soldering them onto the wires) the head of the thermistor is larger, large enough to not go properly in. Arghety-argh-argh. Since I have a spare, I'll try sanding off part of the head.
Did some macro shots of the old (grey) and new (purple) filament, focusing on places with visible splotches.