Hey guys I finally got some time in solid works to start drawing up my first cnc machine. I am pretty excited about it. Its going to be a 4x4, but It will have plenty of extra space, plus will be as simple as replacing the x members for a later conversion to 4x8 when space allows.

I am now looking for ideas on my Z axis. The X and Y are going to be rack and pinion drive. The table is sort of below the the rest of the frame so that I don't have a moment are on my gantry. I would like to have a decent amount of movement in the Z direction, and it should be able to handle the loadings quite well. I am thinking maybe as much as 8 inches of travel. So here are my guidelines for what I want.

Very rigid, very strong, very simple, needs to keep up with x and y axis when cutting. Could care less about jogging speeds.

My gantry is a piece of 80x80 mm extruded aluminum. My linear rails are 20mm THK rails. The rails are mounted top and bottom of the gantry towards the front. I have a gear rack located under the gantry towards the rear. So there will be a fine line automation drive to use for linear motion. So I have the whole front end of the gantry for Z axis. Any reason not to just use a decent linear actuator?

Thanks al