As with the arch, quadrant models are ground to proper thickness, drilled, pinned and separator applied to the bottom of the die surface.
A Mounting-Plate is attached to the bottom of an Open_Base so it can be filled with stone. Stone is teased around all pins and index grooves are filled with stone. Vibrating the model a little will help settle the stone around the pins and help eliminate bubbles. Next, attach Mounting-Plate to Open_Base and fill with stone and again slightly vibrate.