Anet A8 - Prusa MK3 Extruder Mod

thingiverse

Introduction -------------- This is the Prusa I3 MK3’s extruder adapted for the Anet A8 printer. It is recommended to print the body parts in PETG and the nozzle fan in ABS (don’t even try PLA, it will melt even at low temperature). Some changes were made to the extruder idler to use some standard gears (see the picture). The extruder body and the extruder back were modified as well as the Prusa’s originals are just 1mm smaller to fit the Anet’s bars spacing. The ability to quickly change the filament was one of the reason I wanted to make it. Highly recommended extruder, light and silent even with the stock bearings. Before you begin ------------------- The Anet A8's Z End Stop can't go down to allow the nozzle to be near the hot bed so, before you begin, you need to print this one (or one of your choice): http://www.thingiverse.com/thing:1479176 What you need ----------------- - An E3D V6 extruder heater (or a clone), both the Bowden and the direct counterpart will work ok. - 20cm PTFE tube, most of the time shipped with the Bowden E3D V6 (You will use a smaller part, but better to have some spare) - Some screws and nuts as described in the Prusa’s instruction manual (M3n, M3nS, M3x10, M3x30, M3x40, M3x25, M3x18). - 1xMK8 extruder gear (see the second picture, you’ll need the concave one, not the Anet A8’s original) - 1x625ZZ bearing - Nema 17 Extruder Step motor (Use the one shipped with the Anet A8) - Nozzle fan (Use the one shipped with the Anet A8) - Extruder fan (Use the one shipped with the Anet A8) Instructions ------------- First print all the parts. Use PETG for everything except for the nozzle fan that must be printed absolutely in ABS. I do not recommend PLA for the body part as the E3D V6 will get hot. The only different assembly instruction is for the idler part as it was modified to allow using a standard (and cheap) extruder gears instead of the Prusa’s original Bondtech: - Sand the printed shaft and check that it can fit into the idler’s guides, if not, just sand it more until you can insert it with a slightly friction. Check also that the printed washer can fit in. - Pick the 625ZZ bearing and the washer and insert them into the idler’s guides. Do not force too much as the plastic can crack. The washer must be positioned on the right of the idler guides as seen from the inside (see the third picture). For the instructions on how to mount the whole extruder you’ll have to follow the original Prusa’s MK3 assembly (just skip the filament sensor and the auto leveling probe parts): https://manual.prusa3d.com/Guide/5.+E-axis+assembly/510?lang=en Firmware changes --------------------- You need the latest Marlin configured for the Anet A8. The following changes must be made in your config.h: - Reverse the X axis direction: `// @section machine` `// Invert the stepper direction. Change (or reverse the motor connector) if an axis goes the wrong way.` `#define INVERT_X_DIR true // << Set it to true to invert the extruder X Axis direction` `#define INVERT_Y_DIR false` `#define INVERT_Z_DIR true` - Adjust the travel limits (to center the nozzle to the bed): `// Travel limits (mm) after homing, corresponding to endstop positions.` `#define X_MIN_POS -20.7 // Anet A8 Default Marlin Config is -33` `#define Y_MIN_POS -1 // Anet A8 Default Marling Config is -10` Conclusion ------------- Next **(highly recommended)** step is to calibrate your extruder by following the steps as described here: https://mattshub.com/2017/04/19/extruder-calibration/ That's all. Hope you find it useful! Source -------- This work is based on the original Prusa's MK3 Parts that can be found here: https://www.prusa3d.com/download-printable-parts-stl-mk3