Flattening Rough Lumber by Hand

If you are buying one plane to flatten rough lumber, buy a No. 5 jack and camber its iron — the Taytools #5 Bedrock-style is the pick, and the Big Horn 19328 is the cheap version of the same idea. A cambered jack does most of the work in this sequence and it is the only plane in it that cannot be substituted. The long plane that follows it matters second, and a smoother matters last — which is the exact reverse of the order most people buy them in.

Flattening a rough board by hand is not a skill so much as an order of operations. The board arrives cupped, twisted, bowed or all three, and sawn on a machine that left a surface no finish will sit on. You cannot fix all of that at once and you cannot fix it in an arbitrary order, because each stage depends on a reference the previous stage created. The sequence is the same one every pre-industrial shop used and the same one a machine shop uses today with a jointer and a planer: make one face flat, make one edge square to it, bring the second face parallel, then square the ends. What changes with hand tools is that you choose the plane for each stage yourself.

Stage one: one face flat, with a cambered jack

Pick the face that is closest to flat already, put the board on the bench between stops, and find out where it is high. A winding stick at each end will show twist; a straightedge across the width will show cup; sighting along the length will show bow. Mark the high spots in pencil and plane them off diagonally — across the grain at roughly 45 degrees in both directions — rather than along it.

This is the stage that wants a cambered iron: the edge ground with a deliberate curve, in the region of a 10 inch radius, so the plane takes a thick shaving in the middle and feathers out at the sides instead of digging two tracks. A straight iron taking a thick shaving leaves ridges and jams in the cut. A cambered one removes material fast and leaves a scalloped surface that the next plane erases. Doing this with a No. 5 is the cheap, standard answer; doing it with a dedicated scrub plane is faster on very rough or very thick stock, and how to camber a plane iron covers grinding the curve.

Flat here means flat, not smooth. You are finished with this stage when the board sits on the bench without rocking, the winding sticks agree at both ends, and a straightedge touches across the width everywhere. The surface will look terrible. That is correct.

Stage two: the long plane, and why length is the whole argument

Now take the scallops off and make the face genuinely straight along its length, which is a job decided almost entirely by sole length. A short plane rides down into every hollow it meets and takes material out of the low spots as cheerfully as the high ones; a long plane bridges the hollows and can only cut the high spots, which is what “straightening” physically means. That is the entire case for an 18 to 22 inch plane, and it is why jack plane vs jointer plane is not really a preference question.

Two reasonable choices. A No. 6 fore plane at around 18 inches is the shop-wide compromise: long enough to straighten a face and most edges, light enough to use for an hour, and the one long plane a small shop can justify. A No. 7 jointer at 22 inches is the correct tool if you joint edges for glue-ups longer than about four feet, and the WoodRiver #6's own listing is blunt about the limit — an 18 inch sole starts to follow a long edge rather than straighten it. The cost is mass: the Taytools #7 publishes 9.6 lb, which is a lot of plane to push for a morning.

Use the same plane, or the same length of plane, to square the first edge to the flat face. Set a square against the face, plane the edge, check again, and correct by shifting the shaving to one side of the iron rather than by tilting the plane.

Stage three: thickness, and stage four: smooth

With one flat face and one square edge you have a reference, and bringing the second face parallel becomes marking and removing rather than judging: set a marking gauge to the finished thickness, run it from the flat face all the way around, then plane the second face down to that line with the cambered jack again and straighten it with the long plane. Only then does a smoother come out, and only on the faces that will show. A smoothing plane is a finishing tool; using one to flatten a cupped board is a way to spend an afternoon moving a hollow around.

The practical consequence for buying: of the four planes in this sequence, the one you cannot work without is the jack, the one that most improves the result is the long plane, and the one most people buy first is the smoother. If your money is going in one direction, send it in the order the work happens.

What each plane in the sequence publishes

Two of those four publish an iron thickness and a hardness range; all four publish a length, which is the number that actually decides the work. Note what none of them publish: a warranty. Taytools lists a 90-day return on unused items and nothing beyond it, Big Horn publishes no warranty at all, and Woodcraft's listing for the #6 carries a 30-day defect replacement. In this class the long-horizon question is not the warranty, it is whether the casting is stress-relieved ductile iron — which the Taytools pair and the WoodRiver state, and the Big Horn, by its own listing, does not.

What this sequence does not need

A fourth plane. Jack, long plane, smoother. A scrub plane is a nice-to-have that makes stage one faster on thick stock; a shoulder plane and a block plane are joinery tools with no role here.

A perfectly flat bench. It helps, and it is not a prerequisite. What you need is a surface that does not rock and a way to stop the board sliding: a pair of stops, a holdfast, or a batten screwed to the bench top.

A machine. A jointer and a thickness planer do stages one to three faster, and no tool does stage four better than a hand plane. If you own the machines the hand-tool version of this sequence is still worth knowing, because a board wider than your jointer bed is a hand-tool job whether you planned for it or not.

What it does need is sharpening, more than any other hand-tool job, because you are removing a lot of material and a dull cambered iron simply stops cutting. One stone, one guide, and the habit of stopping to hone before it feels necessary — how to sharpen a plane iron has the sequence, and how to flatten a plane sole is worth reading first if the plane is secondhand.