Q.
I always use dadoes in my case construction. What is the best way to make the dado? I am trying to set up for increased production and I want to get a piece of dedicated equipment for dadoes. I currently use the table saw, but this leaves room for error if the thickness of the plywood changes, since the piece is on top of the blade. I have never seen a router set up for this, but I have heard them talked about.
Forum Responses
If you rabbet the horizontal members, you can control the thickness of the tenon. If you install the horizontal members with the rabbet on the top, you can mask any discrepancies between tenon thickness and dado thickness. This will also allow you to do all of your indexing from the bottom of the cabinet.
We have a router installed on a linear guideway. This guideway is connected to an air piston and produces a hold down clamp. The clamping action flattens your plywood and the linear guideway makes the router groove go straight. This system is marketed under the name Super-dado.
We have a Safety Speed Cut panel router, but there is also a Her-Saf that works pretty much the same. Always perfectly square, always adjusted and ready to use with little or no setup time. Her-saf makes router bits that are easy to change and have all sorts of cutting widths for plywood (under 3/4"), melamine (15/1000 over 3/4"), etc.
We cut and band parts, then dado on the panel router, stopping the dado about 1/2" from the front edge. The pieces that go into the dadoes are notched the depth of the dado (3/16" in our case) back about 1" from the front edge on a router table we set up just for that. We flush up the front edges and nail the box together. Stretchers front and back give you a place to rest drawer slides when installing them with the slides being square with the front. You have wood to wood joints in the dadoes so that glue will add a lot of strength to the case.
The panel router we have sets against a wall, taking little room in front of it. You need room at each end for feeding panels into it. You can set the router at a fixed position in height and push panels through it as well as running the router up and down.
Then I added 1/2" x 4" to each metal crossbar, screwed on with countersunk machine screws, to have a smooth, non-marking back. I didn't like sliding panels on the painted metal frame. We just clamp a piece of 5/8" thick wood to the 1/2 x 4 for stops; we make marks on the melamine for frequently used stop setups. I put a self-stick sanding disc on the bottom piece of 1/2 x 4 behind the clamp so things stay in place when routing. The melamine alone was just a little slippery and sometimes things would move around. Not real pretty, but it works fine.
