It's going the wrong way!

You send it left, it goes right. You send it up, it goes down. Like a record player, round round round round.

In wiring up a Polargraph's motors, there's two things that can go wrong:

1. Swapped motors left to right. This is where the left-hand motor is plugged into the right hand motor socket.
2. Reversed wiring. This is where the two pairs of wires that control each motor are in the wrong order.

To test if you've got your motors wired up correctly, use the controller to issue commands to move small distances at a time, and see if the physical machine's movements match your demands.

Move up and down, and left and right to test.

Up and down responds correctly, but left and right are reversed!

This means you have your left and right motors swapped, AND you have your wiring reversed.

Left and right work ok, but up and down is reversed!

This means your motors are probably wired up correct, but you have your left and right motors swapped.

Something else!

Well that's a pickle. Of course, you could have only one motor wired up wrong, and it could be either one. To test each motor, try to make a move in only one axis (like a diagonal), while paying close attention to what the strings are doing.

• If the wrong string changes length, then you have your motors swapped left-to-right.
• If the string gets shorter instead of longer (or longer instead of shorter), then you have the wiring reversed.

Be methodical.