Divided-Light Doors

Divided-Light Doors

Add a masterful touch with classic glass doors.

By Tom Caspar

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With the right set of router bits, a divided-light door is a lot easier to make than it looks. The key to success is simple: Measure and cut every single part first. To get you going on the right path, I’ll show you a foolproof way to calculate the precise length of every piece. Then you rout, mortise and assemble. Piece of cake.


Tools you’ll use

To build these doors, you’ll need a router table and a set of special bits. You’ll also need a metric ruler, tablesaw, planer, jointer and some means of making mortises. 


Design your door

Let’s start with some old-fashioned terms. The openings for the glass are traditionally called lights. They’re “divided” by bars called  muntins. 

Start by drawing your door. Determine the door’s overall size, the widths of the stiles, rails and muntins, and the size of the lights. 

Next, select a set of divided-light door router bits. Each set is designed for a specific range of door thicknesses and requires a different setup, but the general steps are the same. Visit the manufacturers’ Web sites for details. They’re suitable for doors from 13/16 to 1-1/8 in. thick with 5/8-in. or wider muntins. These bits make tenons; some other sets do not.

Anatomy of a divided-light door

Three major parts make a divided light door: stiles, rails and muntins. Every part is locked in place by a mortise-and-tenon joint. In this six-light door, the two horizontal muntins are the same length as the rails. Three short vertical muntins fit between the rails and horizontal muntins. 

Although proportions vary among furniture styles, in this door the lower rail is 1-1/2 times as wide as the top rail. All the lights are the same size and evenly divided.

Two matched router bits cut all the profiles. The cope cutter shapes the ends of all the rails and muntins. It also forms a short tenon and a rabbet to receive the glass. The bead cutter shapes the long edges of the stiles, rails and muntins. It also forms a rabbet.

Both bits may be adjusted to fine-tune the tenon’s thickness. You simply take apart the bit and add shims above the bearing. These shims come with the bit and are stored under the nut and washers.

Rout the bead

The bead goes on the long grain of the stiles, rails and muntins.

7. Rout beads on the inside edges of the stiles and rails. Position the bit so the lower knife is level with the rabbet made by the coping cut (see inset). Cut beads on both sides of the muntin boards. 

8. Rip the muntin boards. Use a push block with a stop and hold-down board so you can keep the guard and splitter on your saw. The exact width of this cut—3/4 in.—must be the same as the width of the stand-in muntin blocks you used to calculate the vertical muntin’s length in Photo 3. 

9. Rout the second side of the muntins. Use the same push block as you did on the tablesaw. This time the push block is flipped over and the hold-down removed. Caution: You must use two featherboards to hold the workpiece square to the table.

Cut the mortises

Most routed doors merely have cope and stick joints. Mortise-and-tenon joints strengthen a divided light door to carry the extra weight of the glass.

12. Cut mortises in the muntins halfway through from both sides. Place a support block under the muntin so its top edge is within range of the machine’s hold-down. Cut 1/2-in.-deep mortises in the rails and stiles.

Assemble the door

The entire door must be glued at one time. It’s best to work directly on a large, flat assembly table so you can slide each piece home before clamping it.

16. Cut 1/16 in. off the ends of the vertical muntin tenons. As originally routed, each tenon is slightly over 3/8 in. long. That’s too long for the through mortises in the horizontal muntins, which are 3/4 in. wide. 

17. Glue the door. Squeeze-out around the beads can be difficult to clean up, so use a minimum of glue. Sand and finish the door before you install the glass. 

This story originally appeared in American Woodworker July 2005, issue #115.

July 2005, issue #115

Purchase this back issue.

Purchase the complete version of this woodworking technique story from AWBookstore.com.