Buying hardwood isn’t as simple as buying a 2×4 at your favorite lumber yard. Here’s the lingo:
First, a 2×4 probably will not be 2″ x 4″ when you buy it. The board did start out that size, actually, but it was cut and sanded to make the finished board 1-1/2″ x 3-1/2″. That same principle applies to all lumber: a smooth 1″ x 6″ is actual 3/4″ x 5-1/2″.
You can buy lumber rough, with no sanded smooth faces or cut smooth edges. It will be rough & splintery. In most lumberyards, though, softwood is sold after it is sanded smooth on all 4 sides. Hardwood is generally sanded smooth on the top and bottom faces of the board.
You can also buy hardwood “SL1E,” meaning that one edge of the board is a straight line, ready for immediate, further processing directly on your table saw. Most hardwood is sold “S2S SL1E,” meaning that the top and bottom of the board is sanded smooth, and one edge is straight. The other edge will be rough, which is OK, because that’s the edge that you will cut off when you cut the board on the table saw.
If you buy the wood cheap, though, you’ll get it rough on all 4 edges. That means you need a way to straighten and smooth the wood. You’ll need a handplane (if you’re dedicated) or either a jointer or electric planer (my choice) to smooth the top and bottom faces of the board. To straighten an edge of the board, you’ll need a shop-made jig. A jig is a tool that you make to help you repeat a process in the shop. In this case, the jig will allow me to straighten rough lumber into usable stock with one straight edge.