What's that tree?

Have you ever been offered some logs or a whole tree for turning, but don't know what it is? The website Discover Life might help. Although it covers all life forms, the tree guide is for woodturners.

To get started you do need a leaf, so be sure to get a sample or two, along with fruits and flowers if available. If no live samples are available check for dead ones under the canopy. Click the appropriate check boxes for leaf type, leaf shape, leaf veins, leaf edge, flower colour and seed colour, then press any of the search buttons.

A list of suggested species appears in the sidebar, and clicking on any of these will bring up a page of information about the species. This is culled from a number of sources, and the amount of information available is very variable.

This tree guide is also a good way of finding information about a species if you already know the name. Click on the Search link at the top of the page and enter either the common name or the scientific name in the search box. It will return all the information on the species from multiple sources. Some of these include Tree Canada, Canadian BioDiversity, Virginia Tech Tree Fact Sheets and the USDA Plants Database.

Some low-tech approaches to drying wood

I acquire a lot of my wood while it is still green; kiln dried boards are expensive and often not available in thickness' greater than one inch. In the maritime climate in which I live, air drying is slow and only gets wood down to about 15% EMC (equilibrium moisture content). This is not low enough for work that is to be glued, or if it is going to find a home in more arid climates.

Anyone setting out to dry their own lumber will benefit from a basic understanding of the physics involved. The rate of drying is determined by the temperature, relative humidity and air flow. The final EMC is determined by the relative humidity:
RH   EMC
  %     %
 80   15
 70   13
 60   11
 50    9
 40    7

Raising the temperature not only makes the moisture more mobile within the wood, but also reduces the relative humidity. If you want to know more about drying wood I highly recommend reading Wood and How to Dry It (Fine Woodworking)

I usually err on the side of caution when seasoning wood to avoid defects such as splits or honeycombing so I try to be patient and let the wood dry slowly. Every piece of green lumber has its end-grain sealed with either paraffin wax or proprietary end-seal.

It is then stickered somewhere cool to air dry to below 20%, preferably 16%. This may take some months, but unless I am in a particular hurry, this is better than risking it splitting. The back room in my workshop is cool, and makes a good starting point. After a month or two I may move it into more normal room conditions until I think it is safe to put it into a 'kiln'.

A moisture meter is an invaluable tool to help you assess how drying is proceeding.

One simple way of drying wood that I have used in the past is to place a table (plywood and folding legs, not a good one) over a hot-air floor register. A cloth is draped over the table top, large enough to reach the floor all the way around. It is weighted down at the back and sides but left free at the front to encourage hot air to pass all the way through the chamber.

Wood is stickered inside, leaving a space above the register to promote even airflow. The advantages of this system are that it is cheap and easy to set up, and costs virtually nothing to run as the heat eventually warms the house. The main disadvantage is that the operating temperature and humidity can only be controlled by adjusting the register or lifting the table cloth. As a rough guide I find that it takes one month for every inch of thickness. The whole contents are removed and checked once a month. Anything dry enough to use is removed. The remainder is returned to the back of the chamber nearest the register and any free space filled with new wood. The temperature can get up to 40°C and the humidity down to 40%, but generally it runs at about 30°C and 55%. This will depend a lot on the humidity in the house and how much the furnace is running. I find that most woods get down to about 8% EMC. It doesn't work anywhere near as fast as a commercial kiln, but is far better than air drying alone.

I have dried 3.5" oak from green to 10% in less than 9 months using the two techniques above..

The 'kiln' described above obviously isn't going to work during the summer months, so I have a simple solar kiln in the back yard. It is essentially a greenhouse, a wooden frame covered in UV stabilized polythene. Black polythene is stapled to the inside of the frame in order to keep direct sunlight off the wood, and to absorb heat.

Box lids and wood movement

I once took some nicely fitting boxes to a craft show and by lunch time the lids were all stuck. Since then I have have pretty much given up trying to make boxes as a commercially viable product. Never the less, here are a few thoughts that may help boxmakers refine their process.

First, it's important to realise that a round box and lid will become oval as their moisture content changes, so they may need to be turned upto 90 degrees to get them aligned properly before they will fit.

Rough turning and leaving for several months before finishing may help, both in drying and relieving stress in the wood. In practice I have not found this to be a complete solution to the problem.

Choice of wood may be critical. Look for a wood that shrinks very little, or has similar shrinkage characteristics in both tangential and radial directions. Some of the lowest North American T/R ratios (1.2 - 1.3) are yellow birch, southern magnolia, eastern hophornbeam. Some of the highest are beech, black cherry, American elm, sugar maple, up in the 1.9 - 2.2. I have to admit that most of the boxes I have tried in the past were maple, so maybe I will have to try again with yellow birch or hophornbeam.

Treating the wood to limit movement might be worth trying. Rough turn and leave to dry, then soak in a finish like danish oil before finish turning. There may also be mileage in trying one of the solutions that some bowl turners use for green wood, such as LDD or alcohol, or a proprietary product like pentacryl. I'm not sure though how well these will work on dry wood.

Another thing to consider is the climate you turn in. It might be worth turning boxes only when the RH is mid range, maybe 60%, rather than at an extreme like 30% or 90%.

Turning Boxes, Fine Woodworking DVD Richard Raffan shows step-by-step the techniques and tricks to make elegant turned boxes with perfectly fitting lids. You’ll see firsthand how to do the work, the tools, the techniques, and the subtle rhythm of each process. 55 minutes.View sample video clip.

Turning Boxes with Richard Raffan, revised Revised and updated full-length study of box-turning. When it comes to turning, there is no greater master to learn from than Richard Raffan. Here in Turning Boxes, Raffan reveals the tricks you need to know when turning boxes, from the cutting and seasoning of the wood to finishing the piece.