Sawdust on the Floor

I’m not sure how the subject got started, but I found myself and some friends talking about dumb things we have seen or heard of that belong in the urban legend category. I don’t know how much of what was said was true or how much was just guys having fun together, but one tale brought me up short. The story went something like this, a new wood turner ( no names here), had obtained some freshly sawn lumber that he wanted to turn into bowls. Not wanting to turn the lumber green, and not wanting to let the lumber dry naturally, he decided to speed up the process.

Here is where the story may have been edited by the teller, but the guy decides that he will dry the wood out in his wife’s new microwave oven. The story went on to tell how much family disharmony this act created… no kidding!!  There isn’t a good idea in this tale that I could find. I won’t go into the obvious problems that the idea creates, like the possible contamination of the microwave, or the possible fire hazards, or the ire that may arise from his wife. What I will talk about is the fact that you can’t fool Mother Nature.

Here’s a fact, all wood, whether it is freshly sawn or has been air drying for years will have some water in the wood. We can’t get it all out. The amount of this water is known as moisture content. Moisture content is stated as a percentage. The calculation for the amount of moisture in a board is;

initial wet weight of lumber-dry weight of the lumber X100/ Dry Weight of the lumber

To accurately measure the amount of moisture content in any piece of lumber you would either need a very accurate scale that has an accuracy of a half gram, or a moisture meter. Scales that are that accurate are very expensive and are not readily available. The Lignomat Meter shown at the right, is a much more convenient method of measuring lumber MC. A lot of woodworkers and wood turners often take along a portable MC meter when shopping for lumber as there is no way to accurately gauge the moisture content of a piece of lumber just by looking at it or feeling it. Another item you may wish to have with you when shopping for wood for a specific project is a spray bottle filled with distilled water. Spraying the wood will give you an idea of the grain patterns and highlight any defects that will show when your project has been finished.

Lumber that is used for furniture building will have a moisture content of 8% to 10%. A tree that has just been sawn will often have a MC of 75% to 200%. The moisture content has to be reduced before the lumber is usable.

Wood has to be either kiln dried or air dried. While kiln drying is faster, most home woodworkers, or wood turners simply do not have the equipment to the job correctly. When wood is kiln dried, air movement, temperature and humidity must be all closely controlled. Many of today’s industrial kilns use advanced computer controls to keep these variables. The costs to obtain and maintain a kiln are not economically feasible for most woodworkers or turners.
Air drying requires that the lumber be stacked horizontally, with stickers between each board. These stickers allow air to flow completely around the board, which is essential in the drying process. The general rule of thumb, is that it takes one year of air drying per inch of thickness in the raw lumber.

When wood dries, the outside of the wood dries first, then with time the moisture on the inside will migrate to the surface, and is evaporated. If wood were to be dried too fast, say in a microwave, the surface of the wood will actually dry and shrink while the inside of the lumber would remain wet. The resulting lumber would either warp, buckle or bow, making it totally unusable. This effect on wood is known as “case hardening”, and should be avoided at all costs.

As for the guy in the story, let’s hope it was just a story. Microwaves cook from the inside out, and while this is good for food, it is not the way that nature wants wood to be dried.

Do you know what tool envy is? That’s when you really want a new tool, but just are having trouble justifying the cost to yourself. Well guys, I have tool envy over Festools Domino Joiner.  If you’re not familiar with the Festool Domino Joiner, it is a bench top tool that is used to make loose tenon joints in wood. 

The Domino Jointer works somewhat like a biscuit joiner.  But instead of cutting an oval into your stock, the Domino Joiner cuts a mortise into your stock, which will accept what Festool calls a “Domino Tenon”.  These loose tenons are made of beech wood, and available in five different sizes to accommodate your different sized stock.  The mortise and tenon joint is one of the strongest woodworking joints, but is time consuming to make, and requires several pieces of woodworking equipment to create.  The Domino Joiner is one tool that will quickly and efficiently make this joint. 

The depth of the mortise is preset, with options for 12,15,20,25 and 28 MM deep. The thickness of the mortise is also selectable from 5- 10 MM.  So really all you have to do is square up your stock, mark where you want the mortise, and cut your mortise in both pieces.  And just like using a biscuit joiner, insert the tenon after applying glue, and clamp your work till the glue sets up.  You’re done. The Festool Domino Joiner can also be used to reinforce miter joints.  The Domino Joiner can be set to any of the following preset angles 0, 22.5,45, 67.5 & 90 degrees, or you can adjust it for your custom angle. 

Now no tool is 100% perfect, and as great as this one is, there are a couple of things that need to be considered.  If you are working on an Arts and Craft Piece and you intend to use through tenons where the ends of the tenon are exposed, this may not be to machine for you.  The other thing to consider is the price. Let’s be honest, Festool products are higher priced then some other options. But if you are looking for professional results, then the Festool Domino Joiner should have a reserved spot in your shop.  This is one tool that every serious woodworker should have.