I've been thinking about this this all evening, and because forums are visited by all sorts of people, many beginners, etc. who might take this as a general okay, I just want to add here that using super glue to machine on a mill is definitely NOT usual or the proper way to clamp for machining.
I did it because I felt I understood what the forces on the glue joints would be for this very specific instance, with these specific parts, with their specific orientation, with the cutting direction of the mill head, and with the pressure I would apply by hand and depth of cut, and that I wouldn't exceed them. It was very important to me to be able to listen to the cutter and feel the cut proceed, and I was very careful to adjust my speed continually to what it "felt" like.
Even then there were no guarantees, it was my own personal estimate, and I did try it out on the bearers first as an experiment.
So don't go thinking that just gluing anything down with super glue will work -- it most likely won't, with more or less disastrous results. Super glue is quite shock sensitive, especially along the glue line, and there's a fine line between the forces of an interrupted cut breaking that line, and having it hold for surfacing. The fact that I could easily release the part with some taps of the hammer in the right place should make that clear.
Clamp securely and in accepted milling practice fashion with mechanical clamps, and work safely. I would certainly have used mechanical hold downs on this job if I could have.