Sometimes, after you’ve hogged away most of the wood and the hollow is nearing the final shape, your hands and eyes tell you that one end/side of the bowl has a steeper slope than the other. Your hands and eyes are usually right. But if you want to verify, here’s a simple technique that I started playing around with this year.

Place a slat of wood across the rim of the bowl. A yardstick works well, but it can be any straight stick. Make/choose a reference mark on the stick to line up with the rim of the bowl. Set an adjustable square so that the blade is somewhere about half of the overall depth of the bowl (It doesn’t matter as long as you keep the same setting when checking both ends). Register the shoulder of the square against the stick and slide it forward until the corner of the blade just touches the slope of the bowl hollow. Make a tick mark on the stick at the edge of the blade (or note the measurement if using a yard stick). Now do the same on the opposite end of the bowl. If the slopes are the same, then the blade of the square will register at the same tick mark. Adjust for any differences by shaving more wood away from the appropriate end until the slopes match. You can check different points on the curve by adjusting the blade of the square, but one reference point in the middle is probably plenty.

This same technique can be adjusted in many ways to check the exterior of a bowl and so on. None of this is necessary, but, especially on larger bowls, it can put your mind at ease that you’re where you want to be. Essentially, it’s a very simplified version of a “pointing machine” used for centuries to assure consistency between a sculpted model and a carving in progress. You can see one in use by a master stone carver in a short film called The Stone Carvers. Filmed in 1984, it documents the carving done for the National Cathedral in Washington D.C. The few minutes with the pointing machine begins at 3:45, but you’ll likely want to watch the whole 28 minute film. It won the Academy Award for Best Documentary Short. The Folkstreams website is a trove of unique films on a variety of subjects, and they have a category dedicated to Traditional Arts and Crafts.

I’ll end this post with a couple short video clips of my own. I set up the camera as I used the adze to do the last bit of shaping on the hollow of an oval walnut bowl a couple days ago. It looks a lot different when the same tool is roughing out big chunks earlier in the process. This isn’t a matter of 10,000 hours of practice or anything. It’s simply about referencing/feeling the bevel against the surface and making minor adjustments as the cut proceeds. The bevel provides control by registering against the surface it has just cut.

In the first (one-minute) clip, below, I’m working on the quadrant to my left. I do that with the bowl sitting flat. Notice, near the end, that the final chips will release at the cross-grain trench where the grain direction reverses. The intended boundary of the hollow is marked by a pencil line. Beyond the pencil line, I’ve scribbled with some red pencil to avoid any potential confusion for myself with any other layout lines.

In this final clip, I’m working on the right quadrant. Rather than try to hold the adze awkwardly (sort of backhanded), I hold the bowl up to allow for a more natural swing. This means I can’t quite see the line at times, thus I tilt the bowl back now and then to see how it’s going. After I make the pass inside the edge of the rim, I use that new surface as a landing zone as the adze begins each series of rows/passes that bring the surface of the rest of the quadrant to shape. Each of these passes ends near the bottom of the cross-grain trench. I don’t bother talking in this clip, either. It simply sounds like somebody knocking on your door for three minutes straight. Zero Academy Award nominations.