# Arduino Laser Engraver cd drive - what do i connect where?

I am a beginner in the world of circuit boards and electronics, and this is my first real project. I am making a DIY laser engraver, following the instructions in this instructable.

Here is the circuit layout

As you can see on the two A4988 stepper motor drivers, 1B, 1A, 2A, and 2B pins have the two A's in the middle with the B's on the outside.

When I watch the guy in the tutorial connect the board with the x and y axis, which are directly connected to those pins, he does it straight, with the leftmost pin on the leftmost solder point on the CD drive.

However, when I use the multi-meter on continuity, I have that the two left solder points on the CD drive are a pair, as are the two right solder points. Should I cross the wires over, connecting the two left solder points with the two middle pins, or do it straight from left to right as he did?

Here is the pcb gerber file.

You can read in the datasheet that 1A-1B are a pair(motor coil 1), and 2A-2B are a pair (motor coil 2).

So 1A and 1B should go to one coil, and 2A and 2B should go to the other coil.

That means you should probably solder your wires straight. I don't know about the polarity of your stepper motor of course, so it might run the wrong way or something... Unless you have the datasheet of the stepper motor, you should probably find out by trial and error. That gives you 8 possible configurations:

1B  1A    2A  2B
1   2     3   4
1   2     4   3
2   1     3   4
2   1     4   3
3   4     1   2
4   3     1   2
3   4     2   1
4   3     2   1


The stepper motor won't be harmed if you have the polarity reversed.

You should connect one coil across 1A to 1B and one coil across 2A to 2B. The coil will measure as a small resistance on your meter.

Which coil goes to which and the polarity is not too important for your purposes- if the motor turns in the wrong direction just swap A and B of one pair.