A form box is a open top steel box available in three sizes:

3" square x 2-1/2" deep
6" square x 4" deep
6" x 12" x 4" deep

They are designed to fit into the standard 20 Ton Press. The 6" x 12" Form Box can be shifted from side to side in the press to achieve full pressure over the entire surface of the metal. The matrix die is placed in the bottom of the box (which is backwards from the usual method of using a matrix die). The pads and the die fit the box with just enough clearance to easily remove them.

As you can see, the basic idea is the same as in the book, with the exception of the containment of the pads and the reversal of the die and pads. The box confines the urethane, resulting in all of the pad flowing down into the die, forcing the metal to move much deeper than is possible on the open platen. The raised surface can be selectively controlled within areas for greater shape and volume.

Using the form box requires a number of Matrix Die Blanks, stacked to allow the metal to be formed within the die. The normal 1/4" thick acrylic sheet used for making matrix dies form the majority of the thickness of the "stack", and a top 1/4" thick Kevlar Die Plate (an epoxy resin and fiberglass laminate formed under extremely high pressure) is the actual die surface on which the metal is placed before pressing. The reason for using acrylic for the thickness portion of the die is that it is relatively inexpensive, and fast to saw to shape if you use 1/4" thick material. Just make sure that the one on the bottom has the smallest opening and that the shape gets progressively larger as you add each layer. Any overhangs of acrylic will be broken off and will damage the die.

The reason for using the Kevlar top surface is that the forming action that takes place in the die at the extreme pressures possible in the form box cause the flange portion of the metal to aggressively attack the upper edge of the die. Acrylic will not stand up to it and will break down before you are finished with the first part. Kevlar will still be usable after several pressings.

FORM BOXES
125.627		3" x 3" Form Box with Pusher		$75.00
125.781		6" x 6" Form Box		$85.00
125.627		6" x 12" Form Box with Pusher		$150.00
MATRIX DIE BLANKS (only 3" is stocked)
125.710		3" x 3" Matrix Die Blank		$1.65
KEVLAR DIE PLATES
125.711		3" x 3" Die Plate		$3.75
125.745		6" x 6" Die Plate		$7.50
125.712		6" x 12" Die Plate		$16.00