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by Mark Stephens Feb 7, 2010 19
So you want 1/8″ thick exotic wood, or maybe thinner? Or slice a 3/4″ thick board into some 1/4″ thick pieces? It’s a common question from our customers. “Can you slice a thicker board into numerous thinner boards?” It’s a sensible question because it seems like a big waste of wood to plane a 3/4″ thick board to 1/4″. So, sure, resawing is no problem.
Well . . . sort of.
Check out this great video from The Woodworkers Guild of America about resawing with your band saw.
Looks easy enough, doesn’t it?
Yes. But resawing introduces a few troubles that you should be aware of when you’re slicing boards to get thin hardwoods, whether they’re exotic or domestic.
George Vondriska makes two key comments around 2:40 in the video above: “Just in case something goes wrong” and “let’s see how it goes.” Welcome to the world of making thin wood – you just don’t quite know how it’ll come out.
Let’s say you have a board that’s 3/4″ x 10″ x 60″. You’re going to stand the board on edge and push it against a 10″ section of the band saw’s blade, and that’s a lot of wood to cut through at once; a lot of tension, friction, and heat. The likelihood of the blade wandering increases. And a wandering blade means the saw hogs off more wood leaves you with an even rougher surface. For this reason, you can get more consistent results when you resaw narrower boards.
A wandering blade can also produce a board that’s miscut – the term “miscut” means you end up with a board, or portion of a board, that’s thinner than what you aimed to get. With the right fence set up and good sawing technique, it’s still very possible to have miscut pieces; a really dense wood can fight with a resaw blade, so to speak. Or the tension of your blade can loosen as you work. Or an abnormality in the work piece can cause the cut to go off course.
So what should you do? Never resaw? Well, that’s not the answer. The answer is just be prepared that unexpected things might happen. Resawing is not a procedure for cutting precisely thick pieces; instead, the best practice is to cut for a slightly thicker piece than you want to end up with and then plane or surface sand to finish it off at the right thickness. Rule of Thumb: If you want to end up with 1/4″ thick, cut for about 3/8″ just in case. This is why when we resaw a 3/4″ thick board for 1/4″ pieces in our own mill, we”ll just slice it down the middle and surface the resulting two pieces down to 1/4″. It’s sensible and practical that way.
To sum up:
Take that 3/4″ x 10″ x 60″ board again. Let’s say it’s a quality kiln dried board, perhaps 9% moisture content. In any board, the moisture content is concentrated in the middle of it. So when you resaw that board into two pieces, you now have two pieces that have an imbalance in the water content location of each one: in short, one face of the newly resawn boards is dry, the other has the bulk of the moisture content (the side that used to be the middle of your original board).
And then that side will start to dry. The wood fibers will shrink on one side of the board. The thin board will cup. There’s no getting around this fact. Again, the trick is to learn how to work with this, and react properly to wood movement.
It’s important to realize that cupped boards aren’t hopelessly destroyed. You just have to re-establish the moisture equality on both sides of the wood (for which there are a number of techniques.
Here’s a nice quote from Good Woodworking Magazine:
Ben Plewes says in “How does Wood Work?” from Good Woodworking Magazine:
There is a general misconception that once wood has been seasoned you don’t need to worry about its moisture content anymore. If only life were that straightforward! Wood continues to expand and contract after the initial drying process is complete. In fact wood, even with a synthetic finish applied, will continually adapt to the ambient moisture level that surrounds it. It’s a slow process so you’re not going to see your wood move the minute you open a window but it will move over a period of weeks to match the average conditions around it.
So if you’ve given resawing a try with your bandsaw and ended up with cupped boards, don’t let that fool you into thinking something went wrong. It’s not that the wood was of low quality or that your saw did a poor job, or that you don’t have good technique.
It’s just what happens with thin resawn wood.
Woodworkers Source Offers Custom Cutting
Resawing services are available at all Woodworkers Source stores. Call or come by when you have a board you need resawn into thinner pieces.
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