Difference between revisions of "Inventables Electronics Batch 1"
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Revision as of 15:29, 21 June 2012
ShapeOko kits purchased through Inventables come with a full set of electronics, which includes the following:
- Arduino Uno
- Power Supply
- Stepper Motors
- Emergency Stop
- Terminal Strip
- Cables and Connectors
Arduino and GRBLShield
The Arduino is the heart of the electronics. It contains an AVR Processor, a USB connector, and I/O pins. The Arduino comes with grbl already installed on board. grbl reads g-code that is sent over USB and translates it into movements for the stepper motors on the ShapeOKO. The particular version of grbl on the Arduino also comes pre-configured for the ShapeOKO, and should not require any tweaking to operate.
The GRBLShield plugs into the stop of the Arduino, and is what takes the signals grbl generates and drives the steppers. As shipped from Inventables, the shield has had the micro-stepping changed on the Z-axis driver to enable faster travel speeds.
The power supply provides 24 volts at 4.5 amps. Be careful with it, and don't work on power wires when the power supply is plugged in. The connector that ships with the power supply comes with plugs on both ends. It needs to be modified in order to plug into the GRBLShield. To do this, strip bot yellow wires and both black wires. Twist the yellow wires together, and twist the black wires together. It should look like this:
Arduino, Shield, and E-Stop
Unscrew the top of the E-Stop switch. Then unscrew the silver collar below it. Below that, there is a white collar with a rubber ring on top of it. Screw it all the way down. [image of switch assembly] Fit the switch into the large hole on the case, and then screw down the silver collar to hold it in place. Replace the top. [image of switch installed in case]
Place the Arduino on top of the case. The USB jack should be facing away from the E-Stop switch. Using M3x12 screws and nuts, attach the Arduino to the case. Snug down the screws, but don't make them too tight. You don't want to crack the circuit board. [image of the arduino attached to the case]
The GRBLShield plugs into the top of the Arduino. It only goes in one way -- the power connectors should be on the same side of the Arduino as the USB jack. [image of shield mounted to arduino]
To wire power to the electronics, all you'll need is the (modified) power connector and a piece of solid core wire ~7" long. The E-Stop acts as an interrupt to the power on the GRBLShield, so if something goes horribly wrong, you can kill the power. It has two sides, a red side and a green side. The Red side is the side you want to wire to. Loosen one of the screw terminals on that side, and insert the two twisted black wires from the power supply connector. Tighten it down so that they won't come undone. Strip one end of the solid core wire, and insert it into the opposite end of the red side. Run the solid core wire through the hole in the end of the case, and insert it into the terminal block on the GRBLShield labeled "GND". Do not reverse the power connection. Bad, bad things will happen if you do. Run the two twisted yellow wires through the hole in the side of the case and insert them into the other half of the power terminal block. The power wiring is now complete. [picture of completed wiring]
To allow for a solderless assembly, the stepper motor wires are run into a terminal block which mounts to the Y-axis motor plate with two sets of M3x16 screws, washers, and nuts. [picture of terminal block attached to the side] To figure out where to cut the motor wires, slide the X-axis all the way to the side opposite the terminal block and run the wire to the block. Mark that length, and then cut the wires two inches longer than that. Repeat for the Y-Axis and Z-axis.
The terminal block has 12 connection points. Think of them in groups of four (each group gets the four wires from a stepper). In the far left group, fasten all the wires from the X-axis motor in this order (from left to right): Red, Blue, Green, Black. In the middle group, insert the Y-axis wires in the same order, and the Z-axis wires in the far right group. [picture of terminal block with just motor wires]
Take the grey 4-conductor cable and cut it into thirds. These are the leads that will run out of the terminal strip and into the GRBLShield. Strip both ends of all three cables, and insert them into the bottom half of the terminal block, matching the wire colors (note: there is no blue wire, so match it to white). [picture of completed terminal block]
On the other end of the cables, crimp the motor connectors, making sure to preserve the order of the colors (red, blue, green black). [video of crimping connectors]
The X, Y, and Z cables can then plug into their labeled ports on the GRBLShield. Congratulations, you've built a ShapeOKO!