Generalizing The Solution

I have received a number of useful suggestions on machining from readers gfor which I am very grateful.  Centering the wotkpiece in the vise using parallels to lift it up into position means a bit firmer grasp on the workpiece.

I also decided to come up with a more general solution to excavating chunks of aluminum.  I had originally written C programs to produce gCode for each machining operation, and they were very specific to the face being machined.  This was bad because the definition of width varied depending on work[piece orientation.  I just wrote a more general solution.  Instead of parameters for length to cut, width, height,etc., it now takes six parameters: xs, xe, ys, ye, zs, ze for the X, Y, and Z starting and ending points.  Then it positions the cutting tool appropriately and does the excavation using the feed rate and cutting depth specified on the rest of the command line.  Several different programs have now been replaced with one using different parameters for different faces.