Itty Bitty Double FLEX Extruder

[jasay]

Which hot end and nozzle size are you using?

Hexagon Ø0.4mm hotend, Ø3mm PLA at 205ºC. The hexagon heatsinks/fans seem to be working well as I can touch them right above the fiber/kapton insulation and they are quite cool.
I have Pololu 1209 NEMA14 motors. Voltage on the A4988 drivers is 0.32-0.325VDC which if my math is correct is ~0.8A. When it skips the entire belt path rotates backwards including the metal gear and motor shaft (presumably under the force of the filament pushing back on the hobbed bolt) so I don't believe there is a belt or gear anchoring issue.

[clough42]

Hexagon Ø0.4mm hotend, Ø3mm PLA at 205ºC. The hexagon heatsinks/fans seem to be working well as I can touch them right above the fiber/kapton insulation and they are quite cool.
I have Pololu 1209 NEMA14 motors. Voltage on the A4988 drivers is 0.32-0.325VDC which if my math is correct is ~0.8A. When it skips the entire belt path rotates backwards including the metal gear and motor shaft (presumably under the force of the filament pushing back on the hobbed bolt) so I don't believe there is a belt or gear anchoring issue.

You might try a little higher temperature. I typically run PLA at 225C in the .4mm hexagon. There's something about the hexagon (and some other all-metal hot ends) that requires a little higher temperature.

My firmware fork is also using the standard Type 1 thermistor tables instead of the Makerfarm-modified type 6 tables. This could make small differences at some temperatures.

[jasay]

That did seem to help. Had a print in progress so bumped up the temp on the LCD and was even able to push the speed up to 150% (90mm/s infill) without any skips. Perimeters look good at an effective 75mm/s. Will have to play more with the faster speeds, would be nice . . ..

I've run PLA at 190ºC for years, but you're right it's a different hotend. Funny that hexagon worked just fine at 190-200ºC on the Makerfarm stock extruder though.

[clough42]

The NEMA17 motor is much, much stronger (at least 3X) compared to the NEMA14. Probably 4X once you count the gear ratio. This allows the extruder to force the filament through the nozzle against a much higher back pressure.

The MakerFarm default Slic3r configs for the Hexagon 3mm/.40 all have the PLA temp at 225C.

James

That did seem to help. Had a print in progress so bumped up the temp on the LCD and was even able to push the speed up to 150% (90mm/s infill) without any skips. Perimeters look good at an effective 75mm/s. Will have to play more with the faster speeds, would be nice . . ..

I've run PLA at 190ºC for years, but you're right it's a different hotend. Funny that hexagon worked just fine at 190-200ºC on the Makerfarm stock extruder though.