This is one method. There are several others, such as jigging the tube and drilling with a drill or drill press.
Here, I'm using a pattern (top bearing) bit. I'm mounting the tube over the right size hole, then bringing the bit up through the material.
And the video:
http://www.reefnerds.com/MACO/videos/tubeHole.avi
The video also demonstrates that you make counter-clockwise circles to cut into the direction of the bit rotation. I think the confusion comes from whether the material you are cutting is between the bit and yourself, or whether the bit is between you and the material you are cutting.
Here, I'm using a pattern (top bearing) bit. I'm mounting the tube over the right size hole, then bringing the bit up through the material.
And the video:
http://www.reefnerds.com/MACO/videos/tubeHole.avi
The video also demonstrates that you make counter-clockwise circles to cut into the direction of the bit rotation. I think the confusion comes from whether the material you are cutting is between the bit and yourself, or whether the bit is between you and the material you are cutting.