A Do-It-Yourself Molding Machine
Make a custom molding cutter to match the profile of old sash or other damaged trim.
In the February/March 2004 issue of Fine Homebuilding (#161), restoration carpenter David Gibney explains his process of restoring and reglazing old double-hung windows. Here he describes a unique solution to the challenge of duplicating a sash part that’s beyond repair.
A single-bladed molding head cutter (Sears Craftsman; 800-349-4358; www.sears.com) is an inexpensive, but very effective tool for making sash repairs. This tool comes with a variety of profiles, one of which is a blank cutter blade that can be used like a planer or custom-ground to replicate an odd profile.
1. Installing the custom-made cutterhead. 
2. Tracing the profile onto a blank cutter.
To transfer the profile of a damaged sash part, such as the muntin shown in the photo above left, I first have to put a 35° angle on the end of the muntin (this equals the cutting angle of the rotating blade). Then I use a can of spray paint to trace the profile onto the face of the blade (photo above right).
3. Grinding the profile roughly to shape. 
4. Fine-tuning the profile with a small, round file.
It often takes a variety of bench grinding wheels, Dremel bits (800-437-3635; www.dremel.com) and hand files to carve out the correct profile, but so far I’ve been able to replicate any part of any window sash that I couldn’t get any other way.
David Gibney is a restoration contractor in Smithsburg, Maryland.
Photos: Tom O’Brien
