Woodworker's Guide to Live Edge Slabs: Transforming Trees into Tables, Benches, Cutting Boards, and More

TECHNIQUES

Logs to Lumber

As a woodworker, it’s important to understand how logs get processed into lumber and how the resulting material is dried. This information will not only make you a more educated consumer, but it will also help you ensure that you get what you pay for when you buy lumber and help you determine if lumber you buy is ready to be used.

Understanding the milling and drying process will also help if you mill your own lumber using a bandsaw or chainsaw and help ensure that your labor results in good material. Even if you can easily purchase lumber, cutting your own is fun and allows you to mill species of wood you may not be able to get commercially.

Cutting and Drying

1. With the log positioned on the bandsaw mill, slabs are cut from the top face. The log remains stationary, and the bandsaw is propelled through it. The mill can be set to produce any desired thickness of material.

Sawmills commonly use a circular saw or bandsaw to process logs. Both methods work equally well. Bandsaw mills, Photo 1, are a little more common. Logs are cut while they’re still wet, which is commonly referred to as green. This is important. If a log is allowed to dry it will probably split to a point that it’s unusable. Plus, dry wood is harder to cut than wet wood. Referring to wood as wet or green means the wood contains a lot of water. Wet wood isn’t suitable for projects because, as it dries, the wood will crack, shrink and distort. The amount of water in wood is expressed as a percentage, called moisture content. If the moisture content is 30%, 30% of the log’s weight is water, 70% is wood.

The moisture content of freshly cut logs can exceed 20%. As a general rule of thumb, wood needs to dry to 8% to 14% moisture content before it can be used for indoor furniture. A simple, low tech, approach is to air dry the wood, Photo 2. The wood is stacked with spacers, called stickers, between each layer so air can flow through the pile and over the wood. The end grain is often sealed with paint or a drying-specific sealer. Air drying generally brings wood to 12% – 14% moisture content, which is fine for live edge furniture.

2. Air drying wood is simple, but requires patience. A general rule of thumb is to allow it to dry for one year per inch of thickness. It should be stacked in a place where air can easily flow over it, and it’s best if it isn’t in direct sun.

Wood can also be kiln dried. It’s stickered and placed in a large oven, Photo 3. Kiln drying brings the moisture content down to about 6% – 8% All wood, no matter how it’s dried, will expand and contract seasonally. It’s important to take wood movement into account in your projects. It’s also important to allow wood to acclimate to your environment. Do this by bringing material into your shop at least a few days before starting your projects.

3. On a commercial scale wood is often kiln dried. This is much faster than air drying, often complete in a few weeks.

If you buy slabs directly from a sawmill you can get sequence cut slabs, meaning they were next to each other in the log. This results in bookmatched pieces, meaning that the wood grain is mirrored from one piece to the next.

Common Cuts

4. The two most common methods of cutting lumber are plainsawn and quartersawn. Quartersawn is more labor intensive to cut, and has more waste, so it’s usually more expensive to purchase than plainsawn.

The two most common approaches for milling lumber are plainsawn and quartersawn, Photo 4. Plainsawn lumber is the most common by a long shot. Depending on where the board comes from in the log, it can be more prone to cupping and warping than quartersawn lumber, but plainsawn lumber is much easier to cut and produces less waste. In addition to being more dimensionally stable, quartersawn wood, in some species, can produce a more attractive grain pattern.

Making Your Own Lumber

On a smaller scale, you can mill your own lumber using a bandsaw or chainsaw. The resulting live edge boards can become shelves, charcuterie boards, or other small projects.

For best results, be sure the log you’re milling is still green. Try to mill the log as soon as possible after the tree is cut down. If the bark is still on, leave it on. That will prevent the log from drying too fast and cracking. Paint the end grain of the log with latex paint or end grain sealer. This will help slow down the drying rate if you’re not able to cut the log right away, and it needs to be done to seal the ends of the sawn boards anyway for drying. It’s much easier to seal the end of the log than a bunch of the ends of individual boards.

Bandsaw Milled Lumber

The size of log you can mill with your bandsaw will depend on how heavy a log you can pick up, and on the capacity of your bandsaw. Many woodworkers find they can cut logs up to about 12″ in diameter and 30″ long, depending on the capacity of their bandsaws. It’s helpful to have another pair of hands available for larger logs. They’re heavy.

The first step in bandsaw milling a log is to create flat reference surfaces on opposing faces of the log using a hand-held planer or belt sander, Photo 5.

5. Flat spots on the bottom and top of the log prevent it from rolling as you cut it, and give you a place to easily put a line you can follow when cutting.

Don’t try to cut a log without a flat spot on the bottom. It could roll during the cut, which is very dangerous. If the bark is smooth you could skip the flat spot on top of the log. Using a chalk line, snap a line on top of the log, Photo 6. Align the chalk line with the pith (the bullseye) at the center of the log’s growth rings. This won’t necessarily be the center of the log. Cut the log on your bandsaw, Photo 7, following the chalk line.

6. Snap a line on top of the log. This line should be in line with the pith on both ends of the log.

7. Freehand cut the log, following the chalk line. Use a 2-4 TPI (teeth per inch) blade, as wide as your saw will handle.

You may find it helpful to have someone on hand to help catch the log halves as they exit the bandsaw.

With that first cut done, set your bandsaw fence to your desired lumber thickness and cut the planks, Photo 8. The wood will shrink as it dries, and you’ll surface it to clean it up, so cut the boards at least ¼″ thicker than the finished thickness you want.

8. After the first cut, use the fence on your bandsaw to guide the material as you cut planks from the log.

Chainsaw Milled Lumber

A chainsaw provides a really fast way to turn logs into lumber. If you’re planning on milling lots of lumber with a chainsaw, it’s worth investing in a ripping chain. Ripping chains have different tooth geometry than crosscut chains and are easier to use for rip cuts. But if you’re only doing this once in a while, a sharp standard crosscut chain works just fine.

Lay the log on its side on a pair of 4x4s and mark out your cuts on one end of the log, Photo 9. The 4x4s prevent the log from rolling. As you mark out the thickness of the boards take into account the fact that the chainsaw’s kerf (the material removed as you cut) is quite wide at about ⅜″.

Cut on the lines that you created, Photo 10. Don’t cut all the way through the log. Stop 1″ above the bottom. Cutting a log with the bar parallel to the grain, as shown, is much easier than cutting from the end grain down. If the log is longer than your bar, you can cut from both ends, Photo 11.

Finish the cuts by standing the log on end on top of the 4x4s and cutting vertically through the 1″ of wood you left on the ripping cuts, Photo 12. It’s hard to get great cut quality from a handheld chainsaw, so it’s a good idea to mill the boards extra thick so there’s plenty of room to clean them up.

Drying

Seal the ends of the boards with latex paint or end grain sealer, Photo 13. Stack the boards to allow them to air dry, Photo 14. This can take quite a while. Put them in a place where air can move over the stack. Plywood scraps work well for stickers. The best way to monitor the drying is by using a moisture meter. If, after a few days of measurements, the moisture content is consistent (generally 12% to 14%) the planks have reached equilibrium and are dry. A general rule of thumb is that it will take one year per inch of thickness for the green wood to dry, 2″ boards