“When you’re looking to restore an antique plane for use, the good (and bad) news is that half the battle is often getting a good plane. Although you can bring most anything back into service, if you’ve secured a decent example, the restoration will be minimal.
… Restorable examples can be obtained at antique stores, flea markets, tool swaps, or tool dealer websites. Be warned that they are usually pulled out of barns and attics, and often have the grime to prove it. In dimly lit antique stores, it can be hard to know which examples are worth investing time in and which are better used for stove fuel. There are a few simple things I look for, the first and most important of which is that all the parts are there. Determine if the plane has the iron, cap iron (for double-iron planes), and wedge. Then, look at the stock. Examine whether it is twisted or if it has severe cracks down the length (minor end-grain checks are normal). The next thing to look for is grain orientation at the end grain on the toe. The ideal orientation is with the growth rings parallel to the sole (typically heart-side up). When the growth rings are oriented at a diagonal, the likelihood is greater that the body has warped out of square. This inevitably causes problems for fitting the wedge and adjusting the iron.
Next, remove the wedge with a controlled mallet strike on the top of the stock in front of the throat. Pull the iron out and see how much life is left. If there is less than an inch between the bevel and the screw slot, look for another plane. Chips in the top of totes (handles) are common and purely aesthetic; broken totes are going to need repair. Another area to check is the outside of the stock opposite the cheeks. Sometimes, because of extreme environmental conditions, the plane will shrink in width and pinch the iron, splitting the sides out. This can be fixed, but safely extracting the iron is sometimes a difficult proposition.
Decent-condition but unremarkable examples typically fetch prices between $10 and $40. This is so inexpensive for such a valuable tool that I always recommend selecting the best example you can find.”
– Joshua A. Klein, excerpt from “Carrying Their Legacies: Selecting, Restoring, & Using Wooden Bench Planes” in Issue Four.