roger lance
its been a long....long....time since high school physics but I recall some basic rule that for every application of force there is an equal and opposite impact or force (you'll have to forgive the improper terminology...as I said its been awhile)....no getting away from that....so as pressure is applied to the dog of the vise, there is equal and opposite pressure that has to be absorbed someplace and that is the cap....I'm sure some other component(s) could be engineered to spare the cap this role but at what cost ($$$)??