Friday, July 11, 2014

Grain orientation in panel glue ups

Very often you see the recommendation to alternate the grow ring orientation when doing a panel glue up. Otherwise they fear that your panel will bow enourmously. An example I just plucked from the Internet:

When alternating the cup up and down, you should get a washboard effect in the panel, but not that enourmous bow over the entire length. Now, you almost never use a panel as a free standing object, It is usually build in a construction and the rest of the construction tries to keep your panel flat. When you have all the little cups it is actually harder for the construction to keep your panel flat, because the lever arm is much shorter.

In real life panels don't always behave like they should do either, I have an old table top standing in a corner of the garage. On close inspection it proved to be bowed all the way over the entire width.

But the grain in the individual boards was perfectly alternated, up, down, up, down:

Which shows how usefull theory can be. :-)

In the mean time I am inching forward on the workshop rebuild. The bench is moved into its new position, and I have attached the old table top to the wall above the bench to be used as a tool rack. It starts to feel like home allready!


  1. Just imagine how warped it would be if the boards weren't alternated! :)

  2. I think that I know why it warped like this. it was standing against a brick wall. The wall is always a little colder, so the inside was probably a little wetter then the outside. No amount of alternating will avoid that kind of warpage.

    Now it is mounted to the wall again, it won't get any better...