The Shapeoko community has tried to gather together all the information on this sort of thing which we can find, and share values on the wiki:
http://www.shapeoko.com/wiki/index.php/Materials
You might find some of the reference material of interest and helpful in informing your populating that dialog.
While they (Nomad883 and Shapeoko) are different machines, the underlying principles are similar, and it would be nice if we could add to that all the values for feeds and speeds which have thus far been worked up for the Nomad.