Using a Dadowiz for Routered Dados

One of the most difficult operations in my shop has been lining up dadoes consistently through two boards.
The most,common operation for this is to make book shelves that must bear considerable weight without warping.
the example shown here shows how I would go about ensuring my accuracy and controlling the depth of cut using a device called *Dadowiz.*

From dadowiz

#1 is the first piece of melamine
#2 is the second piece of melamine
#3 represents a shelf that is 7/8 inches thick
The pencil lines shown as #4 and #5 depict the intended location of the dado for both parts.

From dadowiz

This photograph shows me lining up to the 1/2 inch mark on the Dadowiz with the pencil mark on my material.
As shown here, Dadowiz can run on either the right or left hand side of the guide as required.

From dadowiz

Dadowiz is supplied with three steel pins that slide into three holes on the surface of the device. By loosening a set screw on top you can wedge the intended insert between these pins and set the width that your router bit will cut for you.

From dadowiz

I deliberately chose a board that was 7/8 of an inch thick to demonstrate how easy it is to make this adjustment. Normally most shelf material would be cut from three-quarter inch melamine which can vary in thickness depending on where it is manufactured. This poses several difficulties when setting a stacked dado in the table saw.

From dadowiz

This picture simply shows the router held by the clamping guide in the Dadowiz making the first pass through the melamine. I like to make one shallow pass in this material to minimize chipping at the interface. When cutting melamine it's best to use a spiral down cut carbide which I currently don't have in a 1/2 inch size. In this particular case I'm using a generic 1/2 inch double fluted router bit.
Also note that because the dado is being cut using a one-inch bushing in the router is independent of the router base and does not create difficulties in keeping the base lined up to the center of the router bit which happens most often using homemade router jigs.

From dadowiz

This picture shows the completed dado with the stop in the top board. This is a relatively simple task with this device as the and is already calibrated to lineup with my pencil mark. I just need to square the cut with a chisel and I'm done.

From dadowiz

This picture just shows the finished dado cut to the depth of 3/8 of an inch and spanning both members of the shelf.

From dadowiz

The final picture speaks for itself and shows the dry fit after the milling procedure is completed.
I'm not sure if the device I am using is still in production but I was informed that Woodline has a very similar device which they call the Dadomax that will accomplishes the same thing.