I built my own 3D printer, and used an extruder assembly from amazon. There are a ton of this design being sold there, mostly from China under the name MK8. They differ from the typical RepRap design, in that they have no gear reduction. The stepper (Nema17) has a small burled gear which pushes against a spring loaded tension screw. The steps/mm is very small at 26, but other than that it seems to work well for about 50-100 cubic mm until it starts to act up. The stepper starts to audibly stall, and then when you abort the print and remove the PLA filament you can see it is bulged inside right up against the hot end, but the bulge is still quite firm.
My theory is: I think what is happening is that the heat from the hot end is slowly melting the filament above it making it soft, and now when pressure is applied from feeding the filament it starts to bunch up before it narrows at the extrusion tip. This eventually becomes very hard to push for the stepper, and it eventually stalls out.
Any ideas on how to fix this? Does the threaded part connecting the hot and cold end need some heat sink fans?
I am using 185C for PLA 1.75mm filament and 65C for hot bed, feed rate is 150 mm/min. Printing with printrun default settings, except adjusted for my hotend size (0.4mm) and 0.3mm layer height.
Thanks!
My theory is: I think what is happening is that the heat from the hot end is slowly melting the filament above it making it soft, and now when pressure is applied from feeding the filament it starts to bunch up before it narrows at the extrusion tip. This eventually becomes very hard to push for the stepper, and it eventually stalls out.
Any ideas on how to fix this? Does the threaded part connecting the hot and cold end need some heat sink fans?
I am using 185C for PLA 1.75mm filament and 65C for hot bed, feed rate is 150 mm/min. Printing with printrun default settings, except adjusted for my hotend size (0.4mm) and 0.3mm layer height.
Thanks!
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