The bottom case molding on the John Townsend four drawer block and shell is a fairly challenging piece, the bottom case molding assembly is designed as a web frame. The beauty of the web frame design allows the molding to be very securely attached to the chest and most importantly it allows the case sides to expand and contract.. The front molding receives two mortises, the two stile and the rear rail are joined with floating tendons.
The front molding is milled from a piece of 1 1/2" thick x 3 7/8" wide piece of Mahogany, Sketchup produces a pattern for the bottom case molding, here we see the molding after the profile has rough band sawn, being pattern routed.
A custom made router bit was ground with the molding profile, this bit is large and heavy, it removes a tremendous amount of material. When shaping the front molding we staged the cut replacing the 5/8" bearing with a 1 1/8" bearing, then proceeded to a one size smaller bearings for each successive pass...
Here we see taking a pass with a larger installed bearing..
This wacky looking offset router base flush trims a surface level with the rear portion of the base. We will use this setup to remove 1/8" from the top of the molding, the removed 1/8" will 'hide' the joint between the web frame and the bottom of the main case.
Here we see the offset router base in action..
The final fitting of the scribed recess needs to be accomplished with carving tools..
After the recess has been cut and the front molding corners carved, we are off to the slot mortiser to cut mortises for the stiles of the web frame..
The front molding is purposely left long, the molding is temporarily clamped to the case (no shown) and the length of excess material is scribed from the case. Here we see the excess material being cut off up to the rear of the molding.
After the exact length miters of the molding is marked in with a knife from the case, here we see the dry assembled web frame.
At the miter saw to make the cuts..
Here we see the bottom side case moldings after being shaped with the custom bit, the two lengths of molding are being cut free on the table saw.
Finally the bottom side moldings glued and nailed to the web frame