¶ Abstract
This section is concerned with buying lumber. There may be different guides for different parts of the world and different lumber vendors, e.g. hardware store versus lumber yard. Those guides are usually not geared towards full-time professional woodworking businesses, as those may have additional avenues of supply.
¶ Metric vs Imperial
Prices are commonly given in boardfoot (imperial) or cubic meter (metric) depending on where you are in the world. Thickness in the US is in quarter steps of an inch, e.g. 4/4 or 8/4. This is nominal thickness, after drying, the boards will most likely be ⅛-¼" thinner. (According to Shannon Roger's research1 asking various sawyers, the quarters stem from notches the mill would snap into in steps of ¼" to set the desired thickness.)
To convert prices in boardfoot to cubic meter, you multiply them by 423; for the reversion, you divide by 423.
¶ Imperial
A boardfoot is 1" x 12" x 12" i.e. 144 cubic inches. Given all dimensions in inches, it can therefore be calculated as
Example
A board, 8/4 thick (2"), 12" wide and 6' (72") long would be 2"x12"x72"=1728 cubic inches divided by 144 equals 12 boardfoot. Or 6'x1' surface is 6 sft at 2" thick is 2x6 = 12 boardfoot.
Board thickness is usually given in quarters, i.e. 4/4 is a 1" thick board, 8/4 is 2".
For construction lumber, the cross section is often described by "x inches by y inches", e.g. 2 by 8 is a 2" thick board 8" wide.
¶ Metric
A cubic meter is 1m x 1m x 1m = 1m³. You can calculate the cubic volume by multiplying the dimensions given in meter, e.g. a 30cm board 5cm thick and 2m long is .3m x .05m x 2m = 0,03m³. If the price of that quality and species is 1200€ per m³, that will end up at 36€.
¶ Terminology
- Hardwood grades: https://www.woodworkerssource.com/hardwood-lumber-grades.html
- Lumber terminology: https://www.highlandhardwoods.com/lumber/lumber-terminology/
¶ General considerations
Buying lumber is important for a good result in a project and can make the difference between a frustrating, bumpy experience and smooth sailing. It is valuable to know and keep the following aspects in mind when selecting and buying lumber.
- Don't take boards that include the pith, unless you know you want to cut it out and use only the sides as they will be quarter sawn. We're still debating in which edge cases including the pith would be a valid strategy
- Check for twist by sighting along the board's edge, same for severe cup and bow
- If you have a moisture meter, bring it along, though professional vendors should be able to tell you the approximate moisture content, it doesn't hurt to double check.
- Start with the cheaper domestic woods, just because you will make more mistakes as a beginner and it's more affordable to learn by commiting them in cheaper wood.
- Expect only to be able to use about half of the material in the finished product (can vary wildly, but be aware that you will have waste). Don't try to fit everything in one board, it will most likely not work out.
- Check for Cracks.
- Expect to cut off 1-2" from each end due to cracks.
- Stay away from knots if possible, they can be problematic in joinery, cut them out if possible or put them in the middle of a part.
¶ Resources
- Lumber grading guide: https://www.americanhardwood.org/sites/default/files/publications/download/2017-10/AHEC Grading Guide_AW_pages_0.pdf