Making a Rabbet/Dado Corner Joint Using the Router Table.

Rabbet/Dado Corner Joint

Here lies some logic and tricks for making a simple corner joint for wood boxes. This joint is as useful for small boxes as it is for case good furniture corners.  When I taught I would demonstrate this process to my students. The work area was a small router table. Students gathered around had a limited view and inevitably needed personal help once they started cutting their own corner joint.  This post is a reference so anyone making this joint can understand the steps. 

Wood for this sample was planed down to exactly 5/8" thick.  The goal is to end up with a snug fit and the two boards flush on the outside.  The router bit used is a 3/16" diameter spiral upcut bit.  Box sides could be any thickness from 1/8" to 3/4", so scale up or down the bit used as needed for the box side thickness.  Some logic for why a 3/16" bit was used here:

The Dado Cut

The dado side is done first.  The router bit used will define the width of the dado.  The dado slot needs to be positioned where the inner edge is 5/8" from the board end.  This will allow the rabbet side to end up flush with the dado side.  Using one board standing up against the fence allows using a second board to create a reference edge to set the bit flush against.  Make sure you have the fence securely locked in place once set.

Setting the distance of the bit from the fence:

  

Then set the height of the bit. A small ruler can be used to help set the height of the bit for the dado cut.  There are also several height setting gadgets out there that could be used.  

You should feed the board, snug against the fence and firmly against the table, from right to left.  The direction that the bit spins will help keep the board against the fence as you feed it through. Feed from left to right (the wrong way!) and the bit spin will try to pull your board away from the fence. You should use a backup board to follow the cut when cutting across the grain. This will prevent the grain from tearing out as the bit exits the side.

To set up for the rabbet cut you'll need to reset the bit height and distance from the fence.

The rabbet side setup can be derived from the dado side it needs to mate to.  

It helps to mark what will be removed when cutting the rabbet end. A common mistake is to cut the rabbet on the wrong side.  You can see in the photo below the area that will need to be removed as it relates to the dado.

Dado End Marked

A scrap of 3/16" thick wood slipped into the dado will make setting the height of the rabbet cut easy.  Raise the bit up until it just touches the projecting scrap. Be sure to tighten the bit adjustment once you have the bit set at the right height. 

Setting bit height for rabbet cut

You can use the dado slot you just cut to set the bit distance from the fence for the rabbet cut. Loosen one end of the fence.  Stand the dado side up and slip the dado over the bit, then push the fence against the board.  

Be sure to lock the fence in place after you've set it!  If the fence moves during a cut it will ruin the project board.

This Rabbet/Dado corner joint is just one of four different joints created for this project box. As it slides together in only one direction it is a good choice for drawer boxes. The rabbeted sides are the front and back of a drawer.  The tongues that hook into the dado on the side pieces will pull or push the side,  which will pull or push the back piece.  An additional front board might be added to cover the rabbeted front box board, possibly extend out to cover added drawer slides, and dress up the drawer.  

The entire joinery box project.  

Any suggestions for making this information more clear/understandable would be appreciated.  I'll edit the post as I refine the videos and process flow.  Just leave a comment.

4D