Anet MK8 extruder filament guides

thingiverse

Inserting filament through the Anet extruder into the nozzle throat can be quite challenging due to open space beside the right filament track in the extruder design. This issue is particularly frustrating when working with bended or flexible filament. The stock extruder also proves unsuitable for flexible filament, as it lacks a tight guiding mechanism after the drive gear. To solve this problem, I have designed two extruder filament guides. One is specifically designed for stiff filaments like PLA, ABS, or PETG, while the other is tailored for flexible filaments such as TPU. Both guides ensure smooth filament insertion and optimal printing performance during the process. The stiff filament guide provides excellent insertion guiding but restricts the stroke of the U-groove bearing to the drive gear. However, this restriction is not necessary when working with stiff filaments, making the stiff guide partially fill this gap for easier insertion. In contrast, the flexible filament guide does not have this stroke limitation. Flexible filaments compress significantly more than their stiff counterparts, requiring the U-groove bearing to be able to hit the drive gear effectively during operation. The guides remain securely in position due to their mounting over the stepper motor shaft and being trapped between the stepper motor and heat sink. Installation of the guide is a straightforward process. First, turn off the printer and unscrew the two bolts that are screwed into the stepper motor through the fan and heatsink, compressing the extruder while doing so. Next, unscrew the extruder lever hinge bolt. Place the guide over the U-groove bearing and slide it onto the stepper motor shaft. Then, screw the hinge bolt back in place and reassemble the fan with heatsink. It may be necessary to adjust the drive gear position on the motor shaft so that its clamp bolt is on the stepper side. Additionally, ensure that the drive gear does not hit the guide during operation. Adjust the open position of the extruder with the bolt in the lever so that it cannot be opened further than required. The guides come in two variants: one with and one without a counterbore hole of 1mm depth, providing clearance for the throat that can stick out. The support for the counterbore hole can be easily removed using a suitable flat head screwdriver. If you are using a 0.2 mm print nozzle instead of the standard 0.4 mm, I recommend printing the stiff guide version 0.2. This adjustment reduces the restriction on the stroke of the U-groove bearing to the drive gear, preventing filament grinding or under-extruding with some softer filaments. The filament transit hole in the extruder lever also presents a challenge due to its ledge, making filament insertion difficult. To overcome this issue, you can insert the entry guide for smooth filament insertion through the lever. To print the guides effectively, use a 0.1 mm layer height setting and 100% infill. PLA filament is recommended due to its good printing properties and hardness.