Thanks Sky. If you close the vise and take a measurement of the square slide‘s length then I’ll have the max opening to record. Here is a 5” Rock Island jaw drawing to see if it is the same as your jaws. Thanks for the great pics and your lucky to own this vise.
Patrick, Prentiss was pretty good about having the same channel width and depth. The center to center on the screws are standard 3”. The width can be fixed with a carbide endmill on your mill. Those jaws should work for you. I made my 4” sets a 1/8 over size to cover the wider jaw towers back...
Here is how I make my bumpers. I built several different sizes with a 3/16 clearance hole to eject the rubber. Like RTM I purchased 1/4” x 4” strip of rubber. These dies can be made on a lathe. Mine were out of A2 then I heat treated them. My woodworking vise with wood jaws were perfect to...