When the old timers changed their homes from fireplace and stove heating, they used gravity hot air, steam, or hot water. Gravity hot air required large return air ducts in the floor, so they put a metal bottom on a joist space to create a duct. Code guys today would have a heart attack to see that done. These large returns needed a cover in the floor, and usually those covers were made out of wood.
|When I had to recently fill in a hole in the floor from an air conditioning duct, I decided to make an old fashioned wooden one, taking inspiration from the old timers. I studied the old ones and realized they used a woodworking technique called a cross lap joint. Most of you are probably already familiar with this technique. I found it to be visually appealing, and easy to replicate. I used a dado blade on my table saw. An adjustable one is ideal, but you can also pick a combination of dado blades about ¼” thick and then cut your strips that exact thickness.|
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Please don’t try anything you see in THISisCarpentry, or anywhere else for that matter, unless you’re completely certain that you can do it safely.
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|I cut my strips a little over-sized and then planed them to make them smooth. Sanding would do the same thing.|
I cut several extra strips since the little nibs could break off in the process. I’d suggest not cutting them to length until after you’ve assembled them.
|I screwed a piece of wood to the sliding miter gauge to act as a fence, and I sent the miter gauge and wood across the dado blade, cutting the first slot.|
|I then made an index pencil mark on the wood and miter gauge, and I moved the wood over the exact width of the planned spaces in the grate. I cut the second slot in the fence, moved the wood back to the index mark, and screwed it back on again.|
If you’re trying a similar project, I recommend that the blade be half or more as high as the strips are wide.
|I placed a little piece of one of the strips in the second slot to act as an indexing pin—I made mine long so I could cut five strips at once—and I waxed the saw top and sliding miter gauge so everything would move smoothly.|
|With my bundle of strips registered against the indexing pin (and clamped securely in place), I cut the first slot in the strips. Next, I moved the strips over and placed the previously cut slot onto the indexing pin before cutting another slot.|
|I repeated that process until the whole length of the strips were cut.|
|I used a soft hammer to work the strips together.|
|If they were tight, I wouldn’t need any glue. But too tight, and they’d be a pain to put together.|
When I was finished assembling, I cut the ends of the strips off, and I used black paint to conceal the inside of the duct and any joists that might show.
Here is the new grate installed in the floor:
With a little floor repair and refinishing, the floor and grate will be as good as old.
I started woodworking as a twelve-year-old, in the 60s—I made an automotive creeper as a 4-H project. I made the rails from oak, and when I cut them on my father’s table saw it filled the room with smoke and left burn marks on the wood. I thought it was because oak was so hard. It took me hours to sand off the burn marks. I have since learned the importance of sharp tools.
In 1975, my wife and I bought our first old house. Being teachers, we had more time than money so we became avid do-it-yourself’ers. I bought my first table saw at a garage sale and asked for power tools for birthday and Christmas presents, and in 1979 we bought an investment property. It needed a lot of wood repairs, which allowed me the opportunity to sharpen my skills and buy more equipment! In 1986, we bought our dream house: an 1875 Italianate-style home. The wraparound porch needed complete reconstruction. The porch was all milled from redwood, salvaged from an old water tower. It took me three summers to build.
I retired from teaching in 2005 and started an architectural woodworking business. I have done a terrific amount of old house woodworking as a volunteer for Habitat for Humanity and for our neighborhood organization’s house rehabs. My wife and I also bought a foreclosed 1870s home to rehab. I spent a winter and a summer making an appropriate porch for it. The challenge of putting back round-topped pocket doors was my first exposure to making curved moldings. It was very satisfying work.