Thoughts on wood and grain

I started writing this on Oct 18.

I bought "real" wood on Sep 12 and started working on it on the 13th.

So I spent somewhere around 30 days putting together a really simple vise.

 

It isn't some be-all/end-all. It's honestly pretty ugly, and it flops around a lot.. But I think it should be flat enough to make my life significantly easier.

And then I spent most of the past couple of days carving out a thing called a "shooting board."

This tool is difficult to describe.

That may be why it's so tough to track down anything concrete about them on the internet.

Which is dumb, because it's actually really simple (in concept).

You start with a flat board and a tail-piece that holds other boards in place. Add another board on bottom to hold it all in place on your workbench.

It looks like the best picture I have at the moment is where I glued up the bottom lip:

The entire point is that you run a really sharp plane across the board's "end grain" to make that part flat.

Wait, What's End Grain?

Wood grain, in general, is something that I've never really considered before.

Oh, sure. I've looked at wood and admired the beautiful patterns in the way it grew.

But, when I was working with power tools, those were mostly just distractions from the actual point.

Draw a line in pencil.

Chop.

Flip the block over.

Chop.

Done.

This is a very fast (and expensive, noisy, and dangerous) way to get things done.

There are times I'd prefer the extra noise and danger.

They're getting fewer and farther between as I get better at doing these things by hand.

When I was working with power tools, I never thought about the variations of things like end-grain.

I mostly thought of wood the same way I think of masonry blocks. Or metal.

It's just chunks of stuff to slice and dice. You cut it precisely, and then you make all the pieces fit.

Wood is totally different.

It isn't really a living, breathing entity.

But it used to be.

And it's still doing a lot that looks like that "breathing" part.

At the very least, it absorbs moisture, which makes it expand. And, when the relative humidity drops, the wood shrinks.

It just never will achieve the kind of micrometer precision you get when you work with metal. 

There are a couple of important details that go along with that basic fact, though. 

One is that metal expands and contracts far more than wood due to temperature changes. This is both good and bad. A metal ruler is generally much less accurate than a wooden one. You could not make an SR-71 Blackbird out of wood, partially because it simply will not expand in predictable ways when it gets hot from the friction of blazing through the atmosphere.

The other is that "high-precision" power tools are really very sloppy compared to hand tools. A hand saw will make straighter, smoother cuts with less tearout (more on that later) than a table saw. You can make boards straighter, flatter, and squarer when using a hand plane than is possible with the machine version.

And that's just the gross physical characteristics. It doesn't consider different experiments I've seen where people compared the way the finished product actually looks. Planing by hand is slower than using a machine, but it's far faster than sanding. And every comparison I've seen (admittedly, not a large, statistically significant sample) looks far better than the equivalent that was machined and then sanded.

But Back to End Grain

The "end grain" is really the part where the respiration happens.

I could very well be totally wrong about this. And the details don't really matter. But...

The end-grain is the chunky part at the end of a board that looks ugly.

Each board is a bunch of fibers that run from one end-grain to the other. It's like a bundle of straws. It's the part that breathes the moisture in and out.

The end-grain is the open mouth of all those straws

 

A big portion of wood cutting is about severing those fibers. When you cut 2 feet off the end of a 2x4, it's a lot like holding that bundle of straws in one hand and slicing through them all with a knife in your other hand.

This is a "cross cut" and is also known as "cutting across the grain."

You can also cut the other direction. Maybe you want to trim that 2x4 down so it's a 2x3 or a 1x4. It's like you held that bundle of straws upright and cut down through the length.

This is a "rip cut," and it can get tricky.

Even with straws, there's going to be a tendency for the knife to slip into the space between and just sever whatever holds them together. So you wind up with a couple of bumpy surfaces rather than a nice "clean" cut where you sliced through the straws precisely and evenly.

Wood's a lot messier than straws.

The fibers are a lot tougher, and they tend to wander around. Depending on the knots, the kind of wood, and the way that wood was cut from the tree, they may wander around a lot.

When you're cutting with a saw, it's very easy for that wandering to force things out of line. When you're using a hand saw, you wind up with a crooked cut, even when you started totally straight.

 

When you're using a power saw, the wood might kickback.

When you're cutting this with something like a plane or a chisel, you have a lot more control.

But then we get back into the twisty nature of those fibers. Odds are, they didn't grow straight up and down. The tree is thicker at its base, so the fibers are going to be at least a little bit slanted.

If you're cutting back toward that base, it's like the fibers are rising up to meet your cutting edge. This is known as cutting "with the grain."

If you're going the other direction, it's known as cutting "against the grain." (I always wondered where those phrases came from).

Cutting against the grain is more difficult. And it can lead to tearout.

 

Tearout is also a problem with power tools. I assume that it's generally a bigger problem, since solutions include things like slowing down and taking shallower cuts.

I've dabbled with wood working since I was a little boy, but I've only learned this in the past couple of months. Before this, I didn't know enough to frame the questions, even if it had ever occurred to me to ask.

If I'd stuck with power tools, I'm not sure I'd have ever learned about the difference between cross cuts and rip cuts, much less the difference between going with vs. against the grain.

Working with hand tools is a much more intimate experience. You spend enough time with each piece that you start to learn about its individual quirks.

Or, at least, I am, so far. Maybe I'll get better enough in the future that it all doesn't take so long.