I run a small furniture shop out of a converted barn. For years, I built tables and straight-edged cabinets, and I thought I had tool skills down. Then a customer asked for a set of dining chairs with scooped seats, the kind that curve down gently to cradle you. I said yes without thinking. That decision taught me more about hand tools than any book ever did.
The trouble started when I tried to hollow out the seat blanks. A standard spokeshave works beautifully on convex curves, the outside of a bow or an armrest. But on the inside of a curve, the flat sole of a regular spokeshave rocks and catches, and the blade digs in unevenly. I fought with it for two days, producing wavy, gouged surfaces that looked like a beaver had been at them. Frustrated, I asked a mentor who builds Windsor chairs what he used. He handed me a ruitool concave spokeshave and said, “Stop trying to fit a square tool to a round hole.” That was my turning point.
Why Standard Planes Fail on Inside Curves
Think about what a plane or a standard spokeshave does. It has a flat sole that references off the wood surface. When you push it across a convex curve, the sole touches at two points and the blade takes a consistent shaving. But on a concave surface, the sole touches only at the middle. The edges rock up and down, so the blade angle changes with every inch of travel. The result is chatter, tear-out, and a surface that feels like corduroy. I watched a friend try to use a low-angle block plane on a scooped seat, and he gave up after ten minutes because the plane tipped and skidded sideways.
The real issue is that a concave shape needs a tool whose sole matches the curve. That’s what a curved-sole spokeshave does. Its rounded bottom follows the hollow, so the blade stays in constant contact at a consistent angle. You still need to read the grain and adjust your stroke, but the tool stops fighting you. I remember the first shaving I took with the ruitool concave spokeshave. It came off as a thin, continuous ribbon, not a bunch of splinters. I literally laughed out loud in the shop. Have you ever had a tool that instantly felt like an extension of your hand? That was the moment for me.
Adjusting Technique and Setup for a Hollowed Seat
Once you switch to a concave spokeshave, you have to change how you hold and push it. With a standard spokeshave on a convex curve, you push away from your body. With a concave one on a hollow, you pull toward yourself, with the tool angled slightly to follow the bowl of the seat. I found it easiest to work from the deepest point outward, cutting uphill against the grain in short, overlapping strokes. The blade on my ruitool sits at a low angle, around 38 degrees, and I sharpened it to a razor edge on a fine stone. A dull blade on a curved sole is a recipe for tear-out, so I keep a second, sharp edge ready.
Another lesson came from the wooden seats of those chairs. I use ash and oak, both with pronounced grain. Inside a hollow, you often deal with reversing grain where the fibers cross the curve. Pushing too fast makes the blade catch. The trick is to take thinner shavings, maybe 0.02 inches, and to skew the tool slightly so the blade cuts at a shearing angle. That reduced the tear-out by ninety percent. I also learned to stop obsessing over a perfectly smooth surface right away. The concave spokeshave gets me to within a millimeter of final shape, and then I switch to a curved scraper or sandpaper wrapped around a cork block. Each tool does its part, but the heavy lifting happens with that curved blade.
Now I build those chairs for several clients a year, and the concave spokeshave is always in the drawer next to my bench. It’s not a specialty tool that gathers dust. It’s the one I reach for every time I shape an armrest hollow, a birdcage lip, or a wooden bowl’s inside. If you’ve been struggling with any concave work, ask yourself this: is your tool’s sole part of the problem? Because I wasted two days before I realized mine was. Fixing that one mismatch turned a frustrating job into the most satisfying part of my week.