Filament failures and thermistor troubles

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.

Yet more tests, yet more filament clogging.

Thomas Riedl is accepting of printing me yet another piece, so now I want to make sure the fan design I found fits properly.

The mount atop the fan is 14 mm high, and will sit roughly top-aligned with the top of the X carriage (perhaps a little higher). The fan itself is 15 mm high. The nozzle is at 55 mm down from the top of the X carriage. The bottom of the heatsink fan is 40mm down. This leaves me with 25mm from duct fan to nozzle, 15mm from heatsink fan. That should fit the 25mm version of this: http://www.thingiverse.com/thing:631311

Installed and set up Slic3r again, setting PLA temperature to 210, bed to 190x200 (no way to mark X as going leftwards), adding Y home at end, leaving the rest at defaults (0.4mm layer height, 3 perimeters and infill). First print was actually quite nice, even without fan and with the temperature for some reason staying at 180C. There is one little gap on one side, and the top (like before) is not very tight.

[Cube #35]

Next I reduced the Y size to 190 to avoid drooling over the each while heating up, actually 180 would be better. Also reduced layer size to 0.3 mm, and now it actually went up to 200C. The front side has a slight waviness to it when seen in the right light. The gappiness on the top decreased, but there is a bit more droop into the infill holes.

[Cube #36]

Reduced Y size to 180 and layer thickness to 0.2mm. Quite nice, actually.

[Cube #37]

With these nice results, I went on to doing a slightly larger design, but less than 13 minutes in it had stopped extruding. I pulled it, and sure enough there were stripping marks.

One post suggested that tangling in the filament spool could be a problem, and indeed I had some. I unwound a fair amount of filament and put it back in a more orderly fashion.

I cleaned the hobbed bolt, reassembled with slightly higher tension, and extruded a bit. It quickly started stripping again, and the extruded filament changed between curling up beneath the nozzle, coming out straight, and coming out at an angle. Sounds like clogging to me. Again:(

From this post, a nice overview of problems that can give these symptoms (though for a slightly different system):

• Nozzle is contaminated with dirt or dust. Can be solved with a careful cleaning or replacing the nozzle. [Should get the tools for a proper cleaning.]
• Filament is too large and jamming in the front end. Measure the filament diameter with a digital caliper and make sure it's not larger than 1.80mm [3mm for me]. Feel along the filament for any bumps. Try a different roll of filament. [All my measurements have been fine.]
• Filament has dust on the outside which is clogging the nozzle. Pass the filament through a sponge just before it goes into the feed mechanism to wipe off dust (also, give the nozzle a good cleaning). [I have recently added the sponge]
• Filament is contaminated with foreign material in the plastic itself. This rarely happens but has been known to be an occasional problem. Get a different roll of filament and clean your nozzle. [I believe igo3d is a reasonable quality, so this is unlikely but not impossible.]
• Too much back-force on the filament path. Check for binding by pulling filament by hand, it should pull smoothly. If it binds or catches at all, this is a manufacturing defect and should be covered by warranty. [Different machine issue]
• Excessive heat buildup in the cool side of the extruder is causing filament to soften in the feed gear. This happens most often with PLA, but If your hot end isn't put together properly (heatsink missing or out of place, fan not working right, etc.) it could happen with ABS, too. If you're an expert user you can easily take apart and reassemble your extruder, but as a novice you probably don't want to do this. This is a manufacturing defect and would be covered under warranty. [Shouldn't be a problem with the heatsink fan]
• Not enough clamping force between the feed gear and the bearing to properly grip the filament. If this component is out of spec it could cause filament to strip rather than feed; this would be a manufacturing defect and covered under warranty. [Just how much should the idler be tightened?]

My filament is actually 3mm, not 2.85 as seems to be the more common variety. While I have a spare spool, it's a rubbery filament, and thus hard to measure accurately. The order calls it 3mm, and I seem to have to apply some pressure to make it measure as 2.85. I don't think I want to add the complications of soft filament until I have normal filament working.

I think I need to do a nozzle cleaning again. Sigh.

Step up the reactor power three more triangles!

Took apart the hotend after failing to do an atomic while it was put together. Saw some black stuff on the second pull. These pulls are more difficult than I'm used to, I guess the tolerances are smaller.

Several pulls later. It still takes a lot of pressure to get filament through, even at 200 C. At 210, it goes smoothly (and slightly smokingly at first!), but soon becomes tougher and eventually it becomes almost impossible to press anything through. The pulls come out clean, though.

Could I be feeding filament too fast? I would rather not turn down the speed, but it could be a start, then up the speed to as much as it can handle.

Could there be a gap between the nozzle and the heat break? Then filament would squeeze in there once it softens enough and gets under enough pressure, and that would create extra drag.

I also need to fix the gears before they eat each other. Dremeled the hole some more, and rotated the nut, now it

Weird. I set up to do a 5cm test extrusion at 25% speed. When I first hit extrude, it ran crazy fast for a few seconds (while actually extruding), second try was indeed at very low speed.

Doing a second test, I notice the filament comes out at an angle before falling down nicely. I seem to remember that being a sign of clogging.

Second test @25% speed, 200C (properly measured) was spot on in length, good.

Third test, same settings, the filament doesn't fall in the same nice circle, but more randomly. Length is 4 mm short.

Pro tip: After doing test extrusion, check for random pieces of filament around the moving parts.

Fourth test @25% speed fell 2mm short. Chalking this up to random variation or poor measurement.

First test @50% speed (50mm/min). Extrusion is now straight and the filament falls in a nigh-perfect circle. 4 mm too short.

Second @50%, accidentally 10cm. Fell 9.5 mm short.

Added a piece of soft foam at the filament intake to get dust off.

Third test @50%, fell 4mm short. I'm starting to see a pattern here.

At 75%, fell 4mm short. Good.

There's definitely drooling going on at 200C.

At 100% speed, fell first 8 then 10 mm short. Not so good.

Back at 75% speed, first 6 mm short, then 5mm, then 6, then 5.

Some posts indicate that the e3d is not the best for PLA, because it has a relatively small heating area, so you need to raise the temperature or lower the speed. That matches what I have seen. I guess I will print at 200 or 210.

Recalibrates ro 204.5. Look, I gained half a millimeter of printing height due to much engineering effort on the e3d team's part.

Putting the new fan duct on. For reference: Red goes on the left of the two bent fan pins,  right goes on the loose wire from the ribbon cable. Gcode to start/stop fan is M106 S127/M107.

The current assembly (not cabled to avoid touching the bed yet). If you look carefully, you'll see the hotend mounting screws sitting at an angle and not all the way in.

Aaand... it's totally misaligned. There is no way this fan will work, it goes over a centimeter below the nozzle. A better design would lay the fan flat like the original, but just have a wider opening for the hotend.

Update: Looks like this design might work: http://www.thingiverse.com/thing:631311

Better hardware, same problems

Dremeled the large gear nut trap enough to get the hobbed bits centered properly

The large gear is mounted slanted enough to move 1.8 mm in and out of the small gear. That brings it awfully close to the bottom of the small gear. I should probably fix that before doing much extrusion.

Some power measurements since I found a power meter:

Idle - 17 W
Heating hotend - 60 W
Keeping hotend hot @185 - 32W
Extruding w/o filament @185 - 32W

Heh - extruder gear ran the wrong way. This is not a pultrusion machine, thankyouverymuch. Switched wires to opposite order and marked black on the flat cable.

50 mm extrusion request extruded 38 mm filament. Time to adjust the firmware. And once more to remember to use floating point. But even with that not enough filament got extruded, in fact even less, and I could see it moving slower and slower. Stripping again? Why does it strip so easily?

Aaand tried to pull out the filament while it was still at about 120, which got it stuck. FML.

Edit: Possible explanation could be that I can't get the material out of the nozzle as fast as I put it in. The extra material melts and starts squeezing back up, increasing back-pressure, especially as it cools down further up. Eventually the back-pressure is enough to cause stripping.

This should then be solvable either by turning down extrusion speed or possibly by increasing the temperature. I can also attempt to check this by finding out the feed rate and seeing if the extrusion rate is (2.85/0.5)^2 times that. 32 times. Seems fast. Could measure by filming.

My smallest fan

Brief update: Replaced one of the screws for the extruder mount with a shorter one so it can get out of the way of the hotend fan. Boy, this is tight design. All things wire up nicely and run, the new hotend heats quickly and cools off slowly. Unfortunately, and I should have checked this before, the hobbed part of the hobbed bolt is not where it should be, due to the nut not being far enough into the gear. Melting was not good enough. I will have to dremel.

The fan on the hotend is small but noisy. Handy, though, that it could be wired to the P connector on the breakout board. Hopefully it'll keep the filament from melting too high up.

Update: An overexposed view of the molten mess that is the nut trap of the large gear. There is a fairly obvious extra layer that should be gotten rid of, though I'm not sure it'll be enough. We'll see.

Putting it back together, again

With a new pair of gears from Thomas, I put the extruder back together again. It took a fair amount of sanding and Dremelling to get the bits to fit, but eventually they did. The screws holding the hotend are rather bent, and not able to reach the holes on the other side:

Getting the extruder onto the X carriage was also quite fiddly, worse than before because this extruder mount is lower and so there's less space below the motor. Not sure why it's so important to have it be as low as at all possible. Once this works, I may just redesign it to be a bit higher and print a replacement. See that little space under the motor? I got a washer and nut in there to meet up with a bolt. Not simple.

At the same time, I've moved from my previous Linux laptop (which, alas, was driving me nuts in a number of ways) to a Mac (which merely confuses my Ctrl/Alt muscle memory). I made a copy of my home directory with all the Arduino stuff, but it wasn't quite enough to get the Arduino program to accept the Sanguino board just yet. Grrr.

I appear to be cursed

My colleague @Thomas Riedl very kindly printed a new Wade's Extruder main part for me, being careful to get the support off nicely. It required a bit of drilling, sanding, and dremelling to get all the parts in, but at least it looks solid.

Alas, the weird version of Wade's I had was not only narrower in the hotend mount, but also taller, so the large gear doesn't fit, it hits the X carriage in a place where I can't just cut a hole.

Fortunately, I had also ordered a Greg's Hinged Extruder, a molded rather than printed version, just in case Thomas ran into problems. It has a strange rubbery top to it, which I a bit later found out was is because they have pre-inserted and closed off the two hex nuts:

So I remount the motor on that, only to find that the gears are not compatible and I could not get the small gear off the motor rod. I suppose I could get a new motor and finally have nothing left of the original extruder. But the old large gear does work, so I can use that instead! After mounting that and the idler, getting the hotend fixed was difficult. Due to extra lee-way, the left-hand screw would actually move the hotend down on its side when far enough in, making the hotend slant:

I'm pretty sure that's a bad idea. But that's not all, once I got everything together, I found that the extruder mount was right-handed instead of left-handed. See how it sits over the edge of the X-carriage with space left on the left:

After disassembling it, I found the mounting screw had actually dug into the hotend:

My best option now seems to be to have Thomas print a new large gear - looks like I need a 37 tooth 5mm pitch gear, though it's possible a 39 tooth one would work, which is nice because that's the normal one with Wade's.