How is a chair seat’s top formed? Is it sanded into shape, or is there a different way to contour the wood?
Sandor Nagyszalanczy: Traditionally, solid wood chair seats were carved out by craftsmen using hand tools. An “inshave” (a tool that looks like a tightly curved draw knife) was used for roughing out most of the waste from the seat. Sometimes, carving chisels or a “scorp” (a shaving tool that looks like a two-inch diameter oval-shaped scooping tool on the end of a handle) may have been used to refine details on the chair seat. Finally, the surface was cleaned up with a curve-edged scraper blade and/or sandpaper. In the modern woodshop, chair seats can be rough carved using a router and a special compound-curve shaping jig (see page 70-71 of my book, Woodshop Jigs & Fixtures [Taunton Press, 1994]). Production shops often use a CNC (computer-numerically controlled) router to carve chair seats. A CNC machine (which may cost $100k or more) uses a router motor moved in three dimensions by a mechanical gantry guided by a computer to carve out the seat.
Carol Reed: It is carved with a hand tool called a scorp. You could also use a chainsaw type wheel on a side grinder, but that has the capability to remove wood too fast. In any event, plan to use hand tools like curved scrapers to get the smooth, curved surface for the chair seat.
Richard Jones: Solid wood seats are usually carved by one means or another. This might be with chisels, an Arbortech carving tool on the end of an angle grinder, or even specialized planer type machines. The end of the job usually involves rasps and sandpaper.