CNC First Steps and Coordinate Systems

This tutorial goes through the initial steps of using a Fireball CNC V90 machine with EMC2 (using the AXIS interface) for the first time.

In the EMC2 interface AXIS the cartesian coordinate system is shown along with the position of the bit, illustrated with a cone:

Connect the motors to the controller board so the following coordinate system is used on the machine. Picking this system is probably a good idea because it seems customary to call the longest axis the X axis. However, note that some people may swap the X and Y axis from what we are using here:

Jogging each axis causes the cone (representation of the bil) to move in the display, and at the same time observe how the machine moves. In AXIS a positive movement in any direction moves the cone towards the letters ‘X’, ‘Y’ and ‘Z’. However on the machine every axis will likely move in the opposite direction. This means that direction of the motors needs to be reversed.

The motor direction is reversed by swapping the ‘A’ and ‘a’ wires. Note that this may not be the case for all motors. Check the documentation that came with your contoller board to be sure.

Once the motors had been reversed the machine movements copied the movement of the cone in AXIS.

The next step is to make sure the machine is moving roughly the correct amount each time. Calculate a configuration (essentially the steps needed to move one inch) for each axis. On the V90 the X and Y axis are 5 threads per inch, but the Z axis is 12 threads per inch. More on how this calculation is performed will be in another tutorial. Plugging these values into the EMC2 configuration should do the trick.

Zero the position of each axis in AXIS and use a ruler to measure the location of the Z axis assembly from the side of the gantry, which is the distance the Y axis is moved in from the side. Jog the Y axis until the display shows it has moved +0.5 inches. Remeasure to confim that the Y axis has indeed moved half an inch.

Repeat these steps for the Z axis.

To be sure you can also create an EMC2 configuration for the V90 in millimeters and repeat the test. Jog each axis +0.1 x 10 times, to move the axis one millimeter.