With all of that out of the way, let's begin.

Start by cutting two pieces of steel the same size. One will be cut from the tool steel and the other from the cold rolled steel. The main difference with this set-up vs. the standard blanking dies that you have made, is that the hinge needs to be 1/4" to 1/2" longer, and the steel below the starting holes needs to be 1/4" longer as well. The reason for this will become apparent as we go along. For example, to cut out an object approximately 2" (50mm) in size (the outside, not the interior cut), the tool steel blanks should be 3" wide x 5" long (77mm x 128mm). The hinge will be approximately 2-1/2" (64mm) long with a base dimension of 1-1/2" (38mm), tapering to a width of 3/8" (10mm) where it meets the edge of the part.

Unlike the standard blanking die, which is all one piece, and does not have a separate punch and die component, the interior cutting die does have a separate piece. This is the part that punches out the interior opening. It will be screwed to the 14 gauge backing plate, using the flathead torx screws. It must be securely and accurately registered so that it can cleanly cut through the metal and not move during the loading and cutting operation. This is accomplished by match-drilling and tapping both the punch and its holder before sawing out the design. By match-drilling, I mean that the two plates are clamped together and drilled simultaneously as a set before un-clamping. This needs to be done in a drill press to insure squareness! To improve the registration capability of the screws, we will be using flat-head screws which have a tapered under side. This taper will "register" itself into the tapered seat that we will drill into the part using what is called a "combination drill & countersink". Because of the size of the screw-heads, the closest that they can be placed to each other is about .200" (5mm) center to center.

With the screw heads drilled as close to each other as possible (.200" or 5mm), the smallest interior punch that you will be able to make is about .250" x .450" (6.4mm x 11.5mm).

In the interest of simplification, and not wanting to get you too far over your head at once, we offer a kit that has all of the machining and layout fluid steps #1 through #8 already done. It includes top and bottom plates, stripper plate, screws, allen and torx wrenches, leaving only the design and sawing to you. I strongly recommend that you purchase at least your first interior blanking die as a kit, as it eliminates a lot of possible confusion. Having seen the first one, it is a pretty straight-forward process to make your own.