Mounting the RAMPS board on the boxed frame
I gave the RAMPS board a nice sturdy place in the frame before connecting the hardware to the board.
- Wood screws
- M3 bolts
- Nylon spacers
- M3 nylon bolts
- Piece of plywood
Mount the nylon spacers with the nylon bolts, like this. You can use iron bolts, but then you have the risk of short circuiting your Ramps board
Mount board on plywood with the M3 iron bolts
The board tucked away in a nice corner of the printer
Unpacking the RAMPS 1.4 board and it’s components.
Stepper drivers with aluminium heatsink. You only need four for the Prusa I3:
- 1 for the X and Y axis
- 1 for the extruder
- 2 for the Z axis
The RAMPS board with the A4988 stepper drivers and heatsinks, below that the Arduino Mega 2560 board.
The bottom side of the RAMPS board, with the connectors for the Arduino
Bag with 15 jumpers
All three jumpers need to be installed under each stepper driver, they control the accuracy of the stepper motor:
|jumper 1||jumper 2||jumper 3||Steps|
I’ve installed the LCD 12864 screen with Controller and a SD-Card reader, a rotary encoder and a 128 x 64 dot matrix LCD display.
With this panel you don’t need a pc any more, the Smart Controller supplies power for your SD card. Further more all actions like calibration and axis movements can be done by just using the rotary encoder on the Smart Controller. You can print your 3D designs without PC, just with a g-code design stored on the SD card.
Connecting the board to the printer, introduction.
Below an overview of connectors on the RAMPS 1.4 board.
Detail of the end-stop and thermistor connectors
Adjusting voltage output
You have to adjust the Pololu Stepper Drivers before you can attach the motors. The low voltage Nema 17 Stepper Motors which can take a maximum current of 1.68A at a 2.8V. The Polulo A4988 Stepper Driver can drive up to 2A, this is far higher than the level required, resulting in the stepper motors running a lot cooler.
The best starting point is about 0.6x the rated current, this is the maximum current the stepper driver can output before requiring a heat sink ( n.b Heatsinks are already fitted).
You can calculate the approximate required Vref Voltage value by making the following calculations :
Vref = Stepper Motor Max Current x Factor Current x 0.4
Vref = 1.85A X 0.6A x 0.4 = 0.44V
So now select DC Current on your Multimeter to two decimal places.
The output voltage can be measured with a voltmeter on the pins shown below
You can adjust the output voltage by gently turning the potentiometer, it should be between 0.40 and 0.50V. If you want to raise the output, you have to turn the potentiometer clockwise, to lower the output turn counter clockwise. If the pololu board needs to drive two stepper motors (like the Prusa I3 Z-axis motors), you have to double the vRef output (eg 0.8 to 1V), otherwise only one motor will turn, or both motors won’t move at all.
Adding an extra USB connector
Because I think it is inconvenient to have a USB cable connected direct to the Arduino board, I have added an extra USB plug to the printer frame, as a strain relief. It is a 30cm USB 2.0 B Male to USB B Female Socket Printer Panel Mount Extension Cable, which is for sale on eBay for a whopping $ 1.54
Step 1. Plan
Step 2. Drill
Step 3. File
Step 4. Mount
Now proceed to chapter 8: the Power Supply