I have a few questions about cutting sliding dovetails with a router into a case side.
I have glued up my carcass and now want my drawer blades to be attached to the sides with sliding dovetails. I am following detailed plans but there is no information regarding this procedure.
Drawer blades are 7/8” thick as the sides are too. I am wanting to cut the dovetail dado 3/8” deep.
First question is what size dovetail bit should I use? I’m thinking 3/4”??
Can I run the router off one straight edge or should I have the base sandwiched between two fences? The length of the cut will be 2” in which is the width of the drawer blades.
After I have gone in 2” with the router can I back it out? Or do I turn it off as it is a stop cut and wait for the bit to stop?
On the project index, look at the sketch of the three drawer side chest and the case construction sheet. He uses 1/2" dovetail bit for 7/8" stock. He uses a jig with two sides to sandwich the router base, and it is screwed down to inside the case. You can back the router out with the bit running, just don't let it lift up. And, the back blade has to be reduced to allow for the thickness of the back.
I have made several chests of drawers with the blades dovetailed into the sides. They have graduated drawers with each drawer shallower than the one below it by the width of the blade.
I made a "ladder" to accomplish all of this. It's a stick with pieces of 1/2" baltic Birch ply fastened to it. The Ply represents the drawer and there is a consistent space between for the blade.
I use a router with a guide bushing and a 3/4" bit (1/2" shank). Clamp the front stiles of the chest, one on each side and route the slots. About 3/8" deep or less with the widest point being less than the thickness of the blade.
Make sure everything is consistent. The styles pressed firmly to the bottom of the ply and held firmly so they never move left to right.
To cut the blades, I put the same bit in the router table and adjust the depth of cut to the same as in the styles. The run the blades vertically. You can sneak up on the cuts and get them nearly perfect. Save some scraps of the blades to practice on.
Sounds much more complicated than it is. To make one chest you probably don't need the ladder, just make a guide for the router and move it to each cut. I was making multiple chests, so the ladder seemed like a good idea. I think it's a good idea to make a jig or guide that holds the router on both sides, either off the base or guide bushing. Keep the router running and pressed firmly down.
If you use Titebond type glue it has the characteristic of gripping and resisting the impact of a hammer but will yield and move nicely under clamp pressure, so if necessary, use a clamp to slide them home.
Many people here will tell you the socket should only be dovetailed on one side and square on the other. Easy to do with hand tools and that may be the reason they were adopted. I think the double dovetail version on mine look fine. Would not be that hard to do the single sided version with a router if you wish.
Bill Tindall has a nifty method for cutting dovetails on both the drawer blades and in the case sides. He's published it here on WoodCentral recently, but I can't get the Search function to work, so I can't give you a link. You might want to message Bill and ask him about it. He uses a home built jig to cut a half tail on the drawer blade and then cuts the female socket in the case side to match. You don't really need a full dovetail for this job, a half tail is plenty strong and easier to cut. Moreover, the joint is hidden so there is no artistic advantage in using a full tail. Bill's method goes quickly and he gets excellent results.
If you back the router out while it's running, the bit will try (and most likely succeed at) to push the router away from the fence and screw up the cut. If you're going to back out with the motor running, your jig will need a fence on each side.
If you turn the router off and back it out, you can use a single board for the fence. (You might need to wiggle the collet with your fingers if the bit gets pinned in there.)
Whatever you do, be sure to waste out the majority of the material with something like a spiral bit before you use the dovetail bit. The end result is much cleaner and the DT bit stays sharper for longer.