I’ve been rebuilding work’s 3D printer after the original 3D printer was stripped for working parts to get another printer working which has now been transferred elsewhere. Upon finding 3 broken Melzi boards in a box, I opted to purchase the Big Tree Tech SKR Mini E3 (version 3.01) to upgrade it along with a nice new touch screen.
Due to the state of the other parts, I also ordered two new fans, a new hotend, thermistor, ceramic cartridge heater and a Micro-Swiss All Metal Hotend with Slotted Cooling Block.
Upon connecting everything to the new board (and having to create some new JST connectors) I found the 3D printer didn’t work straight off and needed flashing with a new Marlin configuration. I opted to use the Creality 3D Ender3 SKR Mini E3 configuration example as the base config.
The first problem was that when I tried to home the printer, the X axis would move to the right a little and the Z axis would rise slightly and do nothing else. I had to invert the X Y and Z axis to get them to function correctly, changing the following from False to True in configuration.h
#define X_MIN_ENDSTOP_INVERTING true // Set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING true // Set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING true // Set to true to invert the logic of the endstop.The next problem was getting the fans to work. I connected the Extruder fan to Fan 0, the board fan to Fan 1 and set the chamber fan to Fan 2. I had to change the pin variables to get these to work. These are set in configuration_adv.h.
#define E0_AUTO_FAN_PIN PC6
#define CHAMBER_AUTO_FAN_PIN PB15
#define CONTROLLER_FAN_PIN PC7 Finally I set the board size for the X and Y axis. These were set in configuration.h. I also amended the printer profile in my 3D printing software to match in Ultimaker Cura.
#define X_BED_SIZE 220
#define Y_BED_SIZE 220Once compiled, I copied the updated firmware to the printer, leveled the bed and ran off three Benchy boat models to test. The first two didn’t come out great but I suspect it was due to the cheap nasty white PLA that I was using. Changing to a decent black PLA and it printed off almost perfectly and subsequent prints I’ve done have come out fine.
In future I’m hoping to get a BL-Touch clone working with it to help get even better prints with better leveling.