Shaping & Refining Curves
Using Rasps and Spokeshaves and Compass Planes
Once you have roughed in the shape of a curve with your saw or drawknife, its time to fair the curve into something pleasing. Sometimes this is just working back to a line but I find there is a bit more artistry in this and often find that what looked good on a drawing gets changed in the moment as I do my own shaping. But then again some of this may just be that shaving curves is so much dang fun with spokeshaves and rasps. This is the sculpture of woodworking where we get to bring our design ideas to life.
There are a lot of ways to accomplish the shaping of curves and a lot of different tools you can use to get the job done.
Spokeshaves: This is my favorite tool. So much freedom to shape and with the same tool I can go from a nasty rough curve to a faired and finish ready shape. The low angle shave is the most versatile spokeshave and it one can have only one this is the path I would choose. The Lie Nielsen Boggs shaves are the smoothing planes of my spokeshave drawer and make a nice follow up if I get any tear out. Personally I don't put much stock in round bottomed or concave/convex soled shaved and find that the typical flat bottomed shave can handle most tasks.
Rasps & Files: When the curves get too tight for a spokeshave or access to the curve is an issue, a rasp is the tool I turn to. These come in a variety of lengths and shapes and "grain" or coarseness. Usually this is a scale of 1-15 with 15 being the finest grain. Rasps can be machine or hand stitched (stitching is the process of cutting in the teeth) and some can be handed. This means the teeth are angled slightly to be in the optimal cutting position when held in the left or right hand. Files are much finer and come in different cuts: bastard, single, or smooth. The length of the file also will determine how fine the cut will be with shorter files having finer teeth.
Compass Plane: As the name indicates this is a hand plane but the sole can be adjusted to be either concave or convex to match a radius. This is really a fine cutting tool like a smooth plane and while a heavier cut is possible I find these planes clog easily and are prone to a lot of vibration due to the lightweight sole and adjustable nature. But when set lightly they are the perfect tool to fairing a longer curve so commonly found in furniture work.
Scratch Stocks: Basically a card scraper or a bit of card scraper cut to a specific profile dragged across the wood can smooth and sculpt your shapes. While these can go from a flat surface to finished profile it is best to rough in the shape and use the scratch stock to refine the shape. Or where I find they shine is unifying a faceted surface or a shape where multiple tools were use with varying scratch patterns. The scratch stock blends it all together nicely.
Trust the Tools and Let them Cut
Using these tools to shape your curves is really just about taking some time to get comfortable with them. Shaping a curve is less about precision and more about feeling the tool and spending time to step back and look at your work. Enjoy the artistry and true craftsmanship of this operation but the key is a light, fingertip grip on all the tools so that you can feel the tool reacting to the surface. Each of the above tools will have its own eccentricities and will behave differently with the grain of the wood and the hardness of the particular species. But for the most part these are meant to be refinement tools. If you find yourself hogging off material then I would consider stepping back to a different tool in the continuum of coarse, medium, and fine.
Watch these Project Videos to See More Curve Cutting in Action
Learn More in The Hand Tool School
In The Hand Tool School I have hundreds of hours of video that specifically shows how to cut curves. Several full scale projects where the turning saw is the star. If you want to improve your skills and throw curves into your project, this is the place to be. In fact, Semester 2 is dedicated to cutting curves entirely
So I have a deal: use "rwwlive" to save 10% at The Hand Tool School