Making a Window Sash or Breakfront Cabinet Door
Classic window sash and breakfront glass doors with molded muntins are challenging woodworking projects. However, I find that working through the detail design in SketchUp clears up any uncertainty in the construction of these complex joints. Below I will show how I go about designing a window sash. The techniques are similar for doing 18th C breakfront doors, however there will be more angled muntins in this case.
Here is the example sash in an assembled and exploded view.
Step 1: I find that it is very important to start out on a sash or door with a detail of the muntin shape. By the way, muntin is an unusual word and refers to the thin connecting molding frames that hold the glass.
Step 2: Having designed the muntin molding we can now move on to designing the rails and stiles. I will use an example of the Top Rail in the next steps as shown in the following illustration.
Step 3: The first step in making the Top Rail is to create the cross-section shape which includes half of the muntin molding shape we created above.
Step 4: Push/Pull the shape into the desired length not including tenons.
Step 5: Locate guidelines for the tenon and Push/Pull to length.
Step 6: The molded edge will require a miter cut to fit up with the corresponding molding edge on the stiles. So we need to make a 45 degree cut on the lower molding. I use a face or plane set at 45 degrees to use with Intersect to create the cut.
Step 7: After Intersection the miter joint will require clean-up of the waste with the Eraser.
Step 8: We need a socket for the vertical Muntin that connects into the center of this Top Rail. Again I make 45 degree planes which are used to Intersect with the Rail.
Step 9: After Intersection, clean-up is required with the Eraser. The finished socket is shown below. I also create the small rectangular mortise for the Muntin tenon end.
Step 10: To create the Muntin, Push/Pull the cross-section shape of the Muntin as shown in the first Step.
Step 11: We need to create the 45 degree cuts on the end of the Muntin. I make planes at 45 degrees to use with Intersect to create this joint.
Step 12: I’ve shown the end joint below after Intersection and clean-up. Also I pulled out the small tenon which will socket into the Top Rail mortise.
Step 13: With the Move Tool, latch onto a corner of the Muntin that corresponds to a matching corner in the Top Rail socket.
Step 14: The Muntins cross one another with lapped joints. The first step is to prepare cutting planes to create the “V” cut for the crossing muntins.
Step 15: After clean-up, I’ve shown below the resulting lapped joint for the vertical Muntin. Note the rectangular cutout that matches up wit an opposite rectangular cutout in the horizontal Muntin.
Step 16: After making the horizontal Muntin, the crossing joint is ready for fit up.
Step 17: Here is a close-up of the final assembly.
I’ve made several doors and sash using these classic techniques. I’m always amazed how strong the structure is even with delicate muntins and heavy glass.