Monday, 16 May 2016

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:

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.

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