FREE Preview Issue
Give A Gift
Magazine Customer Service
Contact Us
Home Online
Issue - #270 April 2002
Cutting Accurate Half-Blind Dovetails Half-blind
Many drawers are held together with half-blind dovetail joints. One quick, accurate way to cut this type of joint is with a router, a 1/2" dovetail bit, a guide bushing, and a special dovetail jig.

The half-blind dovetail jig is a comb-shaped template that fits on a base, see the illustration below. The base has clamping bars to hold the workpieces in place while the router is guided in and out of the “fingers” on the template to cut evenly spaced dovetails on a drawer’s front, back and sides.
To cut dovetail joints with a router and template requires a little planning ahead. For example, the drawer for the chest is exactly 4 3/8" wide. I planned for this width so the opening would accommodate a drawer joined with router-cut dovetails. That is, the width (height) of the drawer front has to be a multiple of 7/8". This produces a dovetail joint that’s symmetrical both on the top and bottom edges, see the photo right.
Dovetail Jig
Another consideration is the length of the drawer pieces. To make sure the corners are square, check that the drawer front and back, as well as the drawer sides, are equal lengths. Once the pieces are cut to size, lay them out and label the bottom edge of each piece, as shown left. Also, number the matching corners.
Set up

Setting up the jig takes some trial and error, so I first used some scrap pieces that are the same thickness and width as the drawer pieces. Then I made test cuts, before going on to the real thing. Start by mounting a drawer side under the front pressure bar and a drawer front under the top bar. Note: The bottom edges should be tight against the left-hand stop block, and the insides of the drawer should face out (Fig. 1). After the drawer front is clamped down, reposition the drawer side so the end is level with the drawer front. Next, mount the “comb” template on the jig. The goal is to have the first notch of the template centered on the bottom edge of the drawer side. If it’s not, change the position of the stop block side to side to adjust it (Fig. 2). Now hold the template flat on the drawer front and tighten the wing nuts (Fig. 3). The location of the stop nuts on the studs may take some minor adjustment.
Figure 1
Figure 2 Figure 3
Router Set-up

The router is guided in and out of the template with the aid of a guide bushing (Detail a, of Dovetail Jig illustration above). Next, mount a 1/2" dovetail bit in the router, making sure the bit is centered in the guide bushing. If it’s not, adjust the router’s base slightly. As for the depth of the bit, start with it 1/2" deep (from the base), but you may need to adjust the height of the bit.

Routing the Pieces

Now all of the drawer pieces can be routed. To prevent chipout on the drawer sides, start by making a light scoring pass, routing from right to left (Fig. 4). Then gently move the router in and out of the fingers, this time moving the router from left to right (Fig. 5). You should be able to feel the guide bushing stop at the back of each notch. After routing, but before removing the pieces from the jig, check that you’ve routed each socket evenly and all the waste is removed. Take a look at the Drawer Layout drawing on page 1. You’ve now routed the joint at the left front corner of the drawer (marked No. 1). Next, rout the right rear corner joint (marked No. 3). Mount the drawer side on the front of the jig, the drawer back on the top of the jig — with the bottom edges against the stop on the left and the insides facing out. The other two joints (No. 2 and 4) are routed with the pieces tight against the stop block on the right side of the jig. Again, always clamp the drawer side to the front of the jig, the inside of the pieces facing out, and the bottom edges against the stops (this time on the right).When routing the right side, follow the same procedure as you did on the left.
Figure 4
To prevent chipout on drawer side, start by making a light pass from right to left. This creates a clean shoulder line.
Figure 5
Now move router left to right, working in and out of notches. Bushing must contact back of notch for complete cut.
Troubleshooting Your Dovetails
Setting up to make router-cut dovetails is always a trial-and-error effort. You may need to fiddle around and readjust trial pieces to get a perfect fit. See below for pointers on how to fix possible problems. Most other problems are usually caused by the pieces not being clamped down in the jig so they’re flush across the top, or because they move out of position as they’re being routed.
Loose or Tight
TOO LOOSE: If joint is too loose, increase bit depth. TOO TIGHT: If joint is too tight, decrease depth.
TOO DEEP: If pins go deep, move template toward you. TOO SHALLOW: If not deep enough, move toward jig.
OFFSET: If pieces don’t align at top or bottom, they may not have been tight against the stops.
© August Home Publishing Company
Magazine Customer Service - Privacy Policy - Terms of Use - Contact Us