Tuesday, 26 April 2016

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.

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