The board was designed to meet the requirements of reliability and easy maintenance in the context of an economic and essential vision.
The power supplies are split (2 power supplies with different power) for better compliance with current demands and greater operational reliability.
All the components chosen are, among other things, easily replaceable and, in some places, a double foot-print has been provided in order to replace the component available at the moment.
Particular attention was given to the ventilation of the whole, both in the general design (ventilation holes in the critical points) and in the forced cooling of the main power supply (intervenes when the threshold is exceeded at 50 °).
The Arduino board is easily removable (only one fixing screw) with all the serial terminations intact and accessible from the outside.
The terminal blocks are equipped with a flying female in order to facilitate the wiring of the wires and any changes to the system.
The higher power power supply is replaceable without welding work.
Glass fuses protect the main current sources and are easily identifiable and replaceable.
Additional features have been provided and can be selected with dip-fix in order to meet any differences in the management software.
The AC network area (alternating current) is protected from inadvertent contact with the user.
The 220 VAC voltage intended for external power supplies is protected by a fuse and supplied with a delay calculated with respect to the Arduino ignition.
The board has 3 LEDs, two mounted on one side of the printed circuit and one on the front panel.
Their function is as follows.
|LD3||Front panel||Green||General ignition (12 VDC power supply working).|
|LD2||Tab (left side)||Red||Active extruder heater.|
|LD1||Tab (left side)||Green||Extruder fan (controlled by software) active.|
In the card there are 2 settable predispositions for removable dip-fixes.
The first (DP2) concerns the operating mode of the start and end stroke micro-switches (on all axes).
Dip-fix switches for end and start of stroke (DP2)
|Dip-fix closed on||Mode||Note|
|C – VCC||Pull-up on positive and micro-switch that brings a mass when it closes (stroke limit).||This is the mode used in the circuit examples of common open souce cards.|
|IN – GND|
|C – GND||Pull-up on mass and micro-switch that brings a positive when it closes (stroke limit).||Alternative operating mode, dependent on the software used.|
|IN – VCC|
|No closure on common C.||No pull-up, the micro-switch carries a mass when it closes (stroke limit).||Mode used on the printer prototype.|
|IN – GND|
An incorrect arrangement of the dip-fixes relating to the limit switches can cause the fuse to break.
Observe what is specified in the table, bearing in mind that the central pins are always C and IN (see board screen printing).
The second (DP1) concerns the A4988 driver, the second concerns
|Dip-fix driver A4988 (DP1)|
|Open||Open||Open||90°||2-step full step.|
|Closed||Open||Open||45°||Half step, 1 or 2 steps.|
|Open||Closed||Open||22,5°||1 wire, 1 or 2 phases.|
|Closed||Closed||Open||11,25°||2 wires, 1 or 2 phases.|
|Closed||Closed||Closed||5,625°||4 wires, 1 or 2 phases.|
To obtain changes on the operating modes, the dip-fixes must be set with the board not powered (the modes chosen will be active at restart).
On the panel there is the general toggle switch, it does not pass the direct voltage to the external power supplies.
The latter is controlled by a relay and is supplied with a small delay on ignition.
The switch is provided with an ON / OFF indication.
CONNECTORS FROM M9 TO M14
They collect the wiring related to the limit switches (micro-switches) according to the following table:
|Function||Name on card|
|X axis lower limit||M9 X-MIN|
|X axis upper limit||M10 X-MAX|
|Y axis lower limit||M11 Y-MIN|
|Y axis upper limit||M12 Y-MAX|
|Z axis lower limit||M13 Z-MIX|
|Z axis upper limit||M14 Z-MAX|
The common polarity can be selected from dip-fix (see related item) and corresponds to the right pin of the terminal (if viewed from the front).
It is identifiable in the general design because it has a square pitch.
The common polarity is well connected to the common of the relative micro-switch:
Manual reset of the Arduino board.
The setting of the switches for the stepper motors of all axes must be done directly on each driver following the table below.
First make sure that the driver’s power supply is disconnected.
WARNING! Do not change the settings of the switches with the driver turned on.
For the Z axis and Y axis motors (4.2 A motors) all switches must be set to OFF (switches 1 to 8 upwards).
For the X axis motor (2 A motor), the switches must all be set to OFF (upwards), with the exception of numbers 1 and 3 to ON (downwards).