An Example of Stock Selection

While milling lumber for a recent project I decided to update this article by adding some examples and quite a few photos. I felt it was important to be more demonstrative of the subject. The project, basically a simple frame, required milling 4 boards, around 3/4 of an inch thick by 4 inches wide, two of which would be 36 inches long and the other two 40 inches long. Using lumber from my dwindling stock pile, I decided to select some ash backer board for the project. It is important to point out that using backer board is quite different from using quality rough lumber so some of the decisions one makes will be quite different.

Backer board is the slab left over that the mill was gripping when flat sawing logs. It is usually available quite inexpensively, if you can find it, and it produces all quartersawn lumber. The downside is that the center of the tree is usually included, or was very near to where it was taken from, and the wood at the very center of the tree has very small rings making it unstable and quite useless for woodworking. This means you have quite a bit of waste. Because there is so much more waste, it also takes longer to prepare. Finally, because the sawmill was trying to get the most out of the log it came from, the backer board tends to be an unusual thickness, and quite uneven in thickness. This means you have to settle for whatever thickness you can get. When using backer board, I always leave myself more room for error, so I cut my rough dimensions with more waste to spare. If I had used premium lumber, I would never have left as much of a fudge factor on my stock.

Here is a photo of the raw backer board. You can't see the mill marks as my supplier planed it up a little to make it more palatable for the consumer. You can see from the end that there was a little water damage to this board. I used a black marker to indicate the extent of the damage and where I was sure to find a good end underneath. Note that I am being very generous with the lumber - I would never be that generous normally. Using a tape measure and a marker I indicate the rough length of the boards. I use a straight edge to draw in the cut line for the ends. I use a marker because it is easier to see. The size of the line is immaterial as we are dealing with a rough length - once cut the end doesn't even have to be straight yet.

The next series of steps are only used for backer board. If you were using premium rough lumber, you wouldn't have to go to this trouble. I am including this as the general ideas used here can be applied to any situation where you have flaws in the rough lumber that have to be removed.

On backer board, as mentioned previously, you usually have the pith at the center of the tree included as part of the slab. The growth rings are far too tight and their curvature is too extreme to be of use as furniture wood. Accounting for wood movement under these conditions is nearly impossible, thus we have to remove the pith. I start by marking out where the center of the tree is, all along the slab. Lining up the marks with a straight edge, I find the line of best fit and draw it in with my trusty marker. This is not a cut line - it merely shows where the center is. Now I have to determine where the pith is so I can cut it out. I normally use the squirrelly grain as a benchmark. I start at the center and scan outwards until the grain looks good then I mark where I believe the transition to be. Do that all along the slab then connect the dots to give you the cut line on that side of center. Then repeat the process on the other side of center.

Is there enough wood left for the part I need? Yes. I also want to ensure that the board I cut out isn't going to be too wide for my 6 inch jointer. The waste lines show the region of the slab where the pith will be removed. Now that I have measured and marked out the area of this slab that will yield the parts I need, I am ready to cut. Remember I left much more waste when dealing with this slab than I would have with premium lumber. Until I start cleaning up the wood I won't really know what lies underneath. That is the chance you take when purchasing backer board.