If I try to speed up, the stepper motor get's hard till it stuck. It seems that the heater is not able to handle speeds higher than 40mm/sec for PLA.
I have some friends with a variety of printers, mostly with "all metal" extruders (no teflon) and they are able to handle speeds up to 200mm/sec with normal temperatures for PLA (about 200ºC). They are able to print normally at 80 to 100mm/sec
. It seems that the "all metal" extruder is able to melt PLA faster and hence print really fast. GEEETECH extruder comes with Teflon pipe. This Teflon is "heat isolator" that cause melt speed to slow down.
With my printer I noticed that if I push by hand a wire of PLA, it goes easily the firsts 4 to 5 centimeters, then it starts to get hard (since the new pushed PLA inside is not melted). Few seconds later, the new inserted PLA is getting hot and I'm able to push more PLA through the extruder. So the speed is limited to the "melting speed" of the extruder.
In order to improve the situation I did some checks:
I fastened the heater screws from the heater aluminum block in order to transfer more heat to the extruder.
I checked the extruder/heater temperature with a multimeter. Check = OK.
I rise extruder temp to 215ºC (220 is the highest limit for this material as per manufacturer).
I noticed that 215ºC for extruder temperature is really hot for this PLA, since at this temp, there is continue ooze effect in the extruder.
I would like how is your experience with printing speeds
If it is possible, to hear how to improve this.... 