Previously, we looked at how to wire up your LED string to the Arduino and the power supply. Today, we’ll be completing a demo of the first sketch and seeing how computers do what they do.
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LEDs are awesome. Arduinos are awesome. Programming gives you the power to make LEDs and Arduinos do exactly what you want them to do. Programming, then, makes you more than awesome! Today, I’m going to show you how to wire up our 64-LED strings to an Arduino.
I’ve updated the GCode CNC Demo on Github with an example of how to run 4 stepper motors. It could be extended to 6, 8, or more. Watch it in action
3D printers, laser cutters, water jet cutters, robot arms, delta robots, stewart platforms, the Makelangelo: all of these are examples of computer numerical control (CNC) machines. CNC machines need to move accurately and on command. Stepper motors are a great way to move accurately – they move a predictable amount and then stay where you put them. To command the stepper motors we need a way to easily turn our human desires into machine instructions into stepper motor steps. In effect we need our robot brain to be an interpreter. I’m going to show you a simple interpreter written for Arduino that lets you move stepper motors for your robots.
These instructions are for the Makelangelo Drawbot v0.1. For all later versions, please visit our wiki.
If any part of these instructions are out of date, confusing, or in any way not clear please contact us and I will fix it quick fast. These instructions are current for v0.8.
The kit should include:
– 2x stepper motors
– 2x motor mounts
– 2x bobbins
– 4x 5mm M3
– 2x 10mm M3
– 1x pen holder ring
– 1x female power plug
– 1x arduino
– 1x motor shield
– 1x 12v2a power supply
(Not pictured: one arduino box.)
You will also need the following:
– a small screwdriver with a phillips head
– some sewing thread or fishing line
– 3x 2″ 1/4-20 bolts. These are available in any hardware store. In this photo I’ve used very long bolts because they’re all I had available.
Count the parts to make sure they are all there.
Screw the 3 1/4-20 bolts into the holes on the pen holder.
When the bolts get close to the center, stick the pen in and tighten one of the bolts until they pinch the pen.
Put it to one side.
Take the steppers out of their boxes.
Attach the motor mounts to the steppers.
Notice how the steppers are mirrors of each other.
Notice how the wires are on the side of the motor mount, never the back.
Put these to one side.
Make sure the bobbins will fit on the stepper shafts.
Make sure the bobbin set screw hole lines up with the flat part of the stepper shaft.
Add the 10mm M3 screw to the bobbin set screw hole.
Slide the bobbin onto the shaft until the middle of the bobbin is lined up with the middle of the five holes on the motor mount.
Gently tighten the set screw onto the flat part of the stepper shaft. Do not overtighten! You’ll know it is enough when turning the bobbin also turns the shaft with no wiggle.
Put your assembled mounts to one side.
Press the motor shield onto the arduino like a sandwich. The electronics are not a sandwich! Please do not eat the electronics.
Arrange the electronics and the arduino.
Attach the wires to the shield. Match the colors and screw until tight.
Attach the female power plug to your shield. Make sure M goes to red and GND goes to black.
Plug in the power.
Mount your motors and electronics to your wall or board. Note that the female power supply should be coming out at the top and all the writing on the motor shield will be upside down. That way the stepper on the left is attached to the left side of the shield and so on. It also keeps the power wire out of the way of the drawing.
You are now ready to attach the strings.
Push the thread through the center hole on the side of the mount and loop it over the set screw. Use the software to wind the bobbin “in” until you have enough thread.
Make a similar loop in the other end and loop it over a 1/4-20 bolt on the pen holder.
Repeat these steps for the other mount, bobbin, and a different bolt on the pen holder.
You should now have two steppers mounted and wired up with bobbins correctly wound and attached to the pen holder. You can now center your pen and start drawing.
In a future update I’ll show you how to add limit switches and auto-centering. For this you need some wire cutting and is considered more advanced.
In a future update I’ll show you how to add a servo for pen up/down. I have not developed a good enough pen holder yet so I am not going to confuse you with instructions that might change later.
