First: Let me say that I love my J1s!
I’ve been experiencing the same extruder issues as many others on this forum and FB Group. Here’s what’s worked to resolve my issues:
1- SPEED - The printing speed needs to be lowered. I’ve successfully printed PETG @ 60mm/s for several 18 hour prints (over double the speed my old printer was capable of). No clicking with everything stock (as-delivered). Brands: Snapmaker, Overature, and Sunlu. All prints in copy mode. Other filaments (PLA and TPU) clicked and under-extruded badly. This was the reason to investigate further…
2- TEMPERATURE - I like to print everything hot to begin with. That being said, no issues with printing the PETG listed above at 235C. It seems that this printer likes the filament temperature on the hotter end of the suggested range. I’ve seen where users have reported colder temperatures helped with their problems. Not sure what to say but, that’s what worked for me.
3- THERMAL PASTE - There’s several mentions of adding thermal paste to the hotends in this forum. Thanks to all that contributed! I used the MX4 to the heat break-heatsink and Slice Engineering Thermal Paste to the thermistor.
4- NOZZLE - Replaced the stock nozzles with E3D MK8 0.4mm nozzles. The idea was mentioned in this forum (again, Thanks!). While there was no mention of this brand, I’ve had good luck in the past.
5- EXTRUDER GEARS - Replaced the extruder gears with Bondtech 1.75mm/5mm gears. The stock idler bearings were not smooth and as others have mentioned, the stock gears’ filament teeth are not as sharp (again, Thanks!).
6- FILAMENT SENSOR SPRING SPACER - REMOVE - This was mentioned in this forum (again, Thanks!). Remove the spacer between the spring and sensor body then re-assemble. This removed some of the filament tension. My extruder body was polished from the filament passing by and the excessive pressure exerted by the spring. I plan to investigate this further and source a lighter spring.
Here’s some other things I’ve noticed while using the J1. They’re not related to the extruder but do help overall quality.
1- EXTRUDER LEVELING - When setting the RIGHT extruder to the same height as the left, carefully tighten the screws while the screen is still showing the position slider (the green bar that moves relative to the nozzle height) and the print bed is bouncing up and down. While the extruder mounting system is capable of holding the hotend securely, it’s not straight when loose. See for yourself! I found that I had to tighten and re-adjust 2-3 times, each time I removed the hot end.
2- LINEAR RAIL GREASE - This is another topic shared on this forum (again, Thanks!) but Here’s some more specific information for US J1 owners:
X-Rail - Amazon sells 3ml syringes and 18ga blunt tip needles. Y-RAIL - Amazon sells 3ml syringes and 16ga blunt tip needles. Also available on Amazon is NLGI 1 grease. Not much grease is needed but grease both locations as noted in this forum (again Thanks!). The rails on both my J1s were noisy and now they’re quiet.