Offcuts: Growth Rings By: Don Heisz

I usually take it as personal challenge to use as few fasteners in my finished projects as possible. It’s almost as if, instead of something being made from many pieces of wood nailed or screwed together, glue makes all those pieces into one piece of wood. And that makes the finished project more satisfying, somehow.
And in a very significant way, that is true: wood glued at the joints becomes completely unified. So, a table top made of 4 glued-up pine 1×10 will act like a single 1X40 (well, more like a 1×32, by the time you’ve jointed all the edges and account for the factual size of the wood). I’m sure you’re all familiar with the idea of alternating the growth-ring pattern when gluing together such boards – to minimize the effects of “crowning”. I think most people have completely accepted that is the proper way to glue together wood by this point, even though it works against what the wood wants to naturally do: one piece wants to cup this way, the next that way. The idea is the overall effect is a piece of wood that stays flatter.

We usually find it best to not work against what the wood wants to do, if we want our projects to look and function well for any longer than a few months. We avoid cross-grain gluing as much as possible, for example. I’ve even heard people say that using dowels in joints is unacceptable if the dowel crosses the grain. I don’t know how long their dowels are, exactly, but I doubt a 3/4 inch cross-grain glued dowel joint will cause any splitting.
There are other examples of working with, instead of against, the wood. It’s wise to check the grain before running your board through the jointer, for instance. Running it the wrong way can cause tiny tear-outs. Another example is how you run the router on the edge of the wood. I start at the end grain and go around counter-clockwise, to minimizes chipping and tear-out (and also to maintain the greatest control of the router). Also, when using a chisel, you should chip such that no split forms with how the grain of the wood runs. And when you sand, you go with the grain.

detail of crack in end grain of wood

I think I have made every mistake possible regarding gluing wood. I have made several glue-ups without alternating the growth rings. I have solidly glued a long tenon in a mortise – including completely gluing a solid wood panel in a frame. One time, when making a desk, I even glued the solid wood top down to the carcass. In this lattermost instance, the result was very bad and apparent within a couple of weeks. The top split in three places.
Why do these things happen? I’ve done all of these with full knowledge of the proper way but, at the time, it seemed like a good idea, anyway. How do you get things like that in your head? Centuries of working with wood has dictated the best and most reliable ways to do things. What do I do? I say, I’ll try it this way this time. Maybe it’s pure irrationality.
But sometimes, it makes sense. If I have a 1/4 inch thick, 1/2 inch long tenon on a piece of 2×6 stock, I don’t think there’s any way the bulk of that wood could crack from completely gluing the tenon. I know many people would disagree, but I have never seen it happen.
And I think there are more important concerns than alternating growth rings when making glue-ups. Adjacent lengths of wood should be of a similar nature – should be from roughly the same part of the tree, in the same orientation. This is not just for appearance of the finished grain (the grain will match better in this instance), but because these two pieces of wood will act the same. People tend to think that once the wood is dry, it’s stable. But wood continues to breathe moisture through changing seasons and while your glue joints may not fail, the stress that can develop between two incompatible pieces of wood can cause cracks to form.

I once wanted to quickly make a television stand. I decided to use already glue-up panels they sell at the hardware store. Made of varying width strips of pine, they come in 14″, 16″ and 24″ wide versions. So, I had my project finished and stained by the end of the day. There are no cross-grain glue joints in it. But the “solid” wood split in four or five places. It didn’t split directly at the glue joint, but tore the wood next to it as one strip of wood in the glue-up twisted out of shape.
I would recommend not making anything out of those ready-made panels.

There is an argument to be made for not alternating growth rings in your glue-ups. the idea is that if you have all the cupping oriented in one direction, then when you screw it down, it will tend to go tighter all the way across. I don’t actually believe it, but it is an argument I saw in a magazine years ago . There are times when the top can rack what it’s attached to – if you have a slender framed body for a table and a 3/4 inch top, the top can twist what it’s attached to. The best bet is always to just try to have a flat top, more or less. Alternating growth rings helps ensure that. But the fact is, what’s flat today might be twisted tomorrow. You do what you can and hope it stays good.

But when it comes time to attach it, use screws.