Your First Log: Deciding What to Cut

What the log is telling you

Before an experienced sawyer touches the clamps, they have walked around the log once and already know most of what they are going to do. They are reading four things. None of them needs a tape measure to see, but all of them decide where the boards are.

Taper

A log is not a cylinder. It is a cone — thicker at the butt (the end that was closest to the ground), thinner at the top. Lying on the mill bed, that means the center of the log runs uphill from the small end. If you saw straight and level through a tapered log, every board crosses the grain at an angle. Sawyers level the center first by lifting the small end (see the toe board, below), and the boards come off parallel to the grain instead.

Sweep

Sweep is a bow along the length of the log — one long curve. Load it with the bow facing up, so the log rests on two points and does not rock, and the first cuts take the curve out. A log loaded bow-sideways gives you boards that are wide at the ends and narrow in the middle, or the reverse. Sweep is the single biggest reason two logs of the same diameter can hold very different amounts of lumber.

The pith

The pith is the small dark center of the end face — the tree's first year. Wood right around it is weak and prone to splitting, and everything else radiates from it. Whatever you decide to make of the center of the log, the pith tells you where that center actually is. On a log whose pith sits off to one side, the "obvious" center of the round is the wrong one.

Shape at the ends

Look at both end faces straight on. Round or oval? If oval, which way does the long axis lean? A round log is forgiving — most opening faces give a similar result. An oval log has a right way and a wrong way to sit, and the difference is real: on small and oval logs, the wrong choice can cost double-digit percentages of the lumber that log could have given. Big, straight, round logs are where guesswork is cheap. Small, oval logs — which is what most beginners practice on — are where it is expensive.

The four decisions inside every log

Once the log is read, the plan comes down to four decisions. Every one of them is made before the first cut, whether you make it deliberately or by default.

1. Which face opens first

The log can be rolled to any angle before it is clamped, and the first flat face you cut sets up everything after it. The trade name for this choice is the "opening face". Beginners ask the same thing in plain words: which side do I cut first? It is the decision with the biggest single effect on how much lumber comes out of the log.

2. How deep to open

The first cut is waste — a curved slab with bark on the outside. Cut too shallow and you have a narrow flat that does not give the log a stable, square face to work from. Cut too deep and you have thrown away wood that could have been a board. The right depth depends on the log's shape and on what you plan to cut from that face, which is why it is a decision and not a rule.

3. What the center becomes

After the sides are squared, the middle of the log is a rectangular block — sawyers call it a cant. Its size is chosen up front: a 6×6 timber, a stack of 2×6s, a 4×8 beam. The cant is usually the most valuable single thing in the log, and it is the decision the other three serve. Pick the cant, and the opening depth and the side boards largely follow from it.

4. What comes off the sides

Between the opening slab and the cant there is often room for one or two boards on each face — the side boards. They still have rounded, barky edges (called wane) that must be sawn off later, so they are extra work. Some sawyers treat them as the prize — the outside of the log has the fewest knots, so the clearest boards live there. Others treat them as a byproduct and go straight for the cant. Neither is wrong. It depends on what you are cutting for.

How a log becomes boards on a band mill

A portable band mill has one horizontal blade that moves up and down. It never tilts. Every cut is a level plane, so to cut a different side of the log you turn the log, not the saw. That single fact explains the whole sequence:

1. Roll the log to the opening position and clamp it. This is decision 1 made physical.
2. Lift the small end if the log tapers — the toe board. This levels the center of the log so the boards run with the grain. The lift is only used while the log is still resting on its round, uncut side; after that, every face rests on a sawn flat and the lift goes back to zero.
3. Open the first face. The slab comes off. If there is room for side boards on this face, they usually wait until the sides are square, because they need a flat reference to be sawn to width.
4. Turn 180° — the sawn flat is now on the bed — and open the opposite face. Two parallel flats.
5. Turn 90° and open a side, taking any side boards. Turn 180° and do the other side. The log is now a cant: four flat faces, square.
6. Saw the cant into boards. Every pass is a level cut through a square block — no more turning, no more taper to worry about. This is the easy part, and the reason the sawyer did everything before it.

One number that trips up every beginner

The saw's height setting is the thickness of wood that will be left on the mill after the pass — not the thickness of the piece coming off. To cut a 1-inch board off a 7-inch cant, you set the saw to 6 inches, not 1. Get this backwards once and the whole rest of the sequence is wrong. Every saw height in a LogMaster cut plan is written this way, and it says so on the sheet.

What a cut plan looks like

A sawyer with twenty years on the mill carries the plan in their head. A beginner does not have that, so the plan has to exist somewhere else. Here is what LogMaster puts in your hand after you scan a log with your iPhone or iPad:

Two things in that list matter most to a beginner. First, the plan is sized to your mill and your products — your blade thickness, your smallest board, the sizes you actually sell or use — not a generic pattern. Second, the opening cut tells you what you should see. When the slab comes off and the flat face is the width the plan said it would be, you know the log is sitting the way the plan expects. If it is not, you know before you cut another board.

Learning from every log, not just surviving it

The point of a plan on your first log is not to skip learning to saw. It is to learn faster. Here is how that works in practice:

You see the decision, then you see the result

Each plan shows you the four decisions made for this specific log — how far it was rolled, how deep it opened, what cant was chosen, which side boards were worth taking. Then you cut it, and you see the boards come off exactly where the plan said. Do that for twenty logs and you start predicting the plan before you open the app. That is the judgment a sawyer builds by ruining boards; you are building it by cutting good ones.

You get a second opinion on the log you are unsure about

Straight, round, big logs need no help. It is the ugly one — oval, swept, a little rot on one side — that makes a beginner stand and stare. Scan it. The plan is worked from the log's actual shape, end to end, not from a guess at the middle.

You keep a record

Every solved log can be saved and exported — the plan, the boards, the scale volume, the cut sheet. Your first season on the mill becomes a stack of real logs with real answers instead of a blur. Go back to the log you struggled with in May and see what a different opening would have done.

Five first-season mistakes a plan prevents

• Opening the face that happened to be up. Logs get loaded however the loader put them. Rolling the log before clamping costs a minute; not rolling it costs wood on every oval log.
• Ignoring taper. Sawing level through a tapered log without lifting the small end gives boards that run out of the grain — weaker, and prone to bowing as they dry.
• Setting the saw to the board thickness instead of the remaining thickness. The number on the setworks is what stays on the bed. See above.
• Chasing every side board. A board with too much wane on the edges becomes a smaller board after edging, or firewood. A plan only takes the side boards that will actually make size after their edges come off.
• Deciding at the log. Standing at the mill working it out by eye, log after log, is the slowest part of a beginner's day. Decide before you clamp — with a plan, or with a habit of walking the log first.