Q Open or cracked glue joints in a panel are causing us problems from time to time. 

The 3-inch-thick walnut tabletops appear perfect when we pack them for shipping. I am thinking: It must be when we dropped the packaged tabletop gently from the fork lift to the floor flat-wise that we are cracking it, but the packaging shows no signs of damage. Yet the top, when the customer opens the package, there is a joint crack. Help please.

A Perhaps the most important concept for any species is that every edge-glued joint should be 1-1/2 times stronger that the wood itself. So, joints IF MADE PROPERLY, should never fail. The wood should crack first. We will look at this issue below.
Almost equally important is that wood does not change its size or shape unless the moisture content changes.

In your case, let us assume the you cut staves 3 inches thick, 36 to 48 inches long, and 4 to 6 inches wide. You are gluing the sawn edges.

To maximize the potential strength when gluing sawn edges, you need an extremely sharp saw. With a dull or even slightly dull saw, you will heat the edge and quickly destroy the potential saw joint. 

This becomes more critical with denser woods, drier woods (under 6.0% MC), and larger diameter saws.

SUMMERTIME. Assume you are sawing the staves perfectly in the more humid summer. Unless you glue the staves within a few hours after sawing —  or store them at 35% RH controlled with an electric dehumidifier — the exposed ends of the staves will pick up humidity and swell maybe 1/32 inch. 

Now a day or two later, you assemble the panel. Because the ends are slightly wider, as you apply clamping pressure, the ends will touch first and develop the correct gap of 0.002 to 0.006 inch. 

However, the core of the panel, 2 feet to 4 feet along the stave does not have exposed end grain, so that portion does not swell in width during short storage times. As a result, there will be a gap in the center, although the ends are gapped perfectly. 
So, maybe we add a clamp or two in or near the middle to pull the center closed or band the stave.

The glue dries, but there is a lot of stress in the middle where the clamps pulled the middle gaps closed. 

This stress is transferred to the glue joint as the glue dries. So, when we remove the clamps, the assembled panel can have a lot of stress in the middle of the joint. 

Subtract this glue joint stress from the maximum stress, and we find that we have little excess stress available so that we can drop a tabletop, or put excess weight  on the table during its life.

WINTERTIME. Assume you are sawing the staves perfectly in the drier winter. Unless you glue the staves within a few hours after sawing, or store them at 35% RH controlled with an electric humidifier, the exposed ends of the staves will quickly lose humidity and shrink maybe 1/16 to 1/32 inch.  

Now a day or two later, you assemble the panel. Because the ends are slightly narrower, as you apply clamping pressure, the center sections of the joint (1 to 4 feet in) will touch first and develop the correct gap of 0.002 to 0.006 inch. 

However, then end gaps will exceed the recommended gap (according to the glue manufacturer), and develop a joint with perhaps 1/3 of the required strength.

SUMMERTIME AND WINTERTIME. There is stress within the living tree, now and then. Internal stress is a rare issue except with crooked logs. Such stress, more common close to the pith (center) of a log) can cause warp in staves. 

Using a machinist’s straight edge is a good quality check to assure straight staves initially. 

As a special warning, warped lumber is a sure sign of tree stress or growth stress.

Due to the high cost of a defect, and knowing that moisture content and plant humidity are critical, certainly checking the moisture of incoming lumber, as well as proper storage of lumber and staves is important, as is following the suggestions above. A pinless moisture meter is ideal for a quick scan of most staves.

Q I am new to working with red oak. Sometimes, there seems to be little to no red color at all. Please open my eyes.

A There are two groups of oak lumber, red and white. There are about 20 commercial individual  species that make up each group. 

Although we can identify individual species if we see the acorn or leaf, once the log is produced, identification of the species becomes almost impossible. It is easier to separate logs into red or white.

In my experience, northern red oak, cherrybark red oak, and Southern red oak trees produce reddish lumber. Of course, every oak log has an inch to three or four inches of white sapwood.  It is rare to eliminate the sapwood when sawing lumber, except export grades, which get special prices.

Bottom line: Find a sawmill that uses mainly a reddish oak species.

Q With our thick eastern white pine lumber, we also notice end cracks as we plane the lumber.  People here say that is normal, but it is indeed expensive. Please comment.

A Eastern white pine does not have a very high resistance against splitting. But, where we run into trouble is sometimes a kiln operator will over-dry many pieces of lumber to assure there are no wet pieces. 

This over-drying can easily reduce the moisture in the drier pieces to 4% MC, especially on the outside fibers where the planer knives are working. Also, EWP dried under 8% begins to get very brittle. 

In general, for the very best EWP, do not let the kiln temperature go over 160F. And never let the kiln humidity go under 7.5% EMC at any time — maybe even 8.0% EMC is the driest. 

If planer and knives designed for oak are used, they will likely pound EWP too much. Make sure the correct tools are used.

Q With the unusually warm weather this spring, we are seeing the large bees flying around the wooden picnic tables at our church. I call them carpenter bees. Any ideas on how it control them?

A Indeed, they are carpenter bees. Every spring as the weather warms, they migrate from many hundreds of miles to the same hole they used last year. They do not eat wood, but instead make tunnels as their nest.

In early spring when the bees first appear is the best time for control. Later, a second crop of bees can increase the work for you.
Control is achieved by waiting for a cool evening or daytime when the bees are not active, but are in their nest. Squirt the appropriate bee killer with two squirts into their hole and then immediately plug the hole with a wooden dowel. Obviously, wear gloves, mask, and eye glasses for projection.   (Specific insecticides for carpenter bees are available in large hardware and lumber stores. Be careful to avoid spillage or overspray, especially on a picnic table.)

Q Where can I get plans and details for your Virginia Tech solar-heated lumber dryer?

A This is the kiln I developed in 1968 when I was at Virginia Tech.  The original document was upgraded by Dr. Bryon Bond at Virginia Tech. They are free. The name of the plans were changed when they were published by other universities. Here is the link: pubs.ext.vt.edu/420/420-030/420-030.html.