I would like to run two SSRs, however most of the easily accessible GPIO pins have already been claimed for other purposes.
Smoothieboards GPIO pins also output only 3.3V which is not always enough to fully switch an SSR. The easy solution would be to connect the SSRs to one of the MOSFETs, but this costs an output that is needed to control heaters and fans. Instead I built a cable which converts Smoothies regular limit switch connectors into 5V outputs by including a 2n7000 transistor.
The first SSR will be used to control the 24V and 72V switching power supplies. This way the printer can completely shut off even if a MOSFET fails closed.
# Switch: Master Power SSR
switch.mpwr.enable true
switch.mpwr.output_pin 1.28 # Z_MIN
switch.mpwr.output_type digital
switch.mpwr.input_on_command M80
switch.mpwr.input_off_command M81
switch.mpwr.ignore_on_halt false
The second SSR will be controlling the heated bed. The 150x150mm 24V 200W heated bed was made by Keenovo and includes an embedded thermistor, adhesive backing, and insulation. This bed will heat up very fast as 200W is quite powerful for its size. The built in silicone foam insulation should further increase its efficiency and will also protect the servos.
I have connected the temperature sensor to the Smoothieboard, but will not be powering the bed itself as it is not attached to anything and could quickly overheat. I am using Fotek SSRs for testing but they will be replaced with a more reliable brand in the final build.
# Bed Temperature Configuration
temperature_control.bed.enable true # Heated Bed
temperature_control.bed.thermistor_pin 0.25 # Sensor T2
temperature_control.bed.heater_pin 1.29 # Z_MAX
temperature_control.bed.beta 3950
temperature_control.bed.designator B
temperature_control.bed.set_m_code 140
temperature_control.bed.set_and_wait_m_code 190
temperature_control.bed.p_factor 100
temperature_control.bed.i_factor 0.1
temperature_control.bed.d_factor 100
temperature_control.bed.max_temp 120
temperature_control.bed.min_temp 0
temperature_control.bed.runaway_heating_timeout 240
temperature_control.bed.runaway_cooling_timeout 900
temperature_control.bed.runaway_range 20
Finally its time to connect the dual extruder assembly. The wiring is pretty messy but the stepper motors and thermistors plug into their designated connectors, and I connected the heater cartridges to the Smoothie's large MOSFETs.
We can borrow the extruder configuration from Smoothies documentation. I have only pasted the configuration for one of the two extruders here as they are analogous and quite verbose.
# Extruder Configuration
# A dual-extruder E3D Chimera fed using direct drive Bulldog Lite extruders.
extruder.hotend0.enable true
extruder.hotend0.steps_per_mm 120
extruder.hotend0.default_feed_rate 400
extruder.hotend0.acceleration 5000
extruder.hotend0.max_speed 50
extruder.hotend0.step_pin 2.0 # Motor 1 Pins
extruder.hotend0.dir_pin 0.5
extruder.hotend0.en_pin 0.4
alpha_current 0.8
# Hotend Temperature Configuration
temperature_control.hotend0.enable true # Hotend 1
temperature_control.hotend0.thermistor_pin 0.23 # Sensor T0
temperature_control.hotend0.heater_pin 2.7
temperature_control.hotend0.thermistor Semitec
temperature_control.hotend0.designator T0
temperature_control.hotend0.set_m_code 104
temperature_control.hotend0.set_and_wait_m_code 109
temperature_control.hotend0.p_factor 74.0
temperature_control.hotend0.i_factor 6.5
temperature_control.hotend0.d_factor 200
temperature_control.hotend0.max_temp 280
temperature_control.hotend0.min_temp 0
temperature_control.hotend0.runaway_heating_timeout 120
temperature_control.hotend0.runaway_cooling_timeout 360
temperature_control.hotend0.runaway_range 20
You can see my complete configuration file here: config.txt
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