Baltic Birch (BB) has nothing to do with a type of birch tree, but more to do with a type of plywood manufactured in the countries surrounding the Baltic Sea, with the two biggest producers being Russia, and Finland. In Europe it is mostly used for cabinet making. In addition to Baltic Birch, there is also a product called Finnish Birch which is generally quite thin, and used for tasks such as building aircraft, musical instruments etc, with the 3-ply plywood version as thin as 1/64″ (0.4mm) (typically available from aircraft parts suppliers like Aircraft Spruce Canada).
Baltic Birch is composed of multiple layers of 1.5 mm-thick solid birch veneer, cross-banded, and laminated with exterior grade adhesive. Why spend more on BB ply versus cheaper versions? Firstly, BB produces a void-free core which makes it better from a fastener holding ability, and produces cleaner joinery. The face veneers are also thicker than traditional cabinet-grade plys. Finally, the exposed edges of BB are aesthetically pleasing and don’t need to be covered up.
Baltic Birch ply comes in 1525×1525mm sheets, which approximates to 5’×5’, and is often sold as 3/4” ply in North America (although one can now find 4’×8’ sheets). But here’s the thing – it isn’t. It is only manufactured in metric, so the 3/4″ equivalent is roughly 11/16”, or 18mm, whereas 3/4” = 19.05mm. 1mm may not seem like much but it does make a difference in cabinetry which takes board thickness into account. The trick when measuring out is to remember this, and either work completely in millimetres, or convert to inches.
There are some companies that just do great work in tool innovation. Woodpeckers seems to be such a company. They exude innovation, with some very cool measuring tools, jigs and fixtures. They even manufacture in the USA. There is only one problem, most of their tools are part of their “OneTIME” tool program, where they manufacture a tool for a certain period, and then “retire” the tool. It seems like an odd way to do business. Imagine the effort involved in designing and then manufacturing these awesome tools, then selling just a small quantity. A case in point is the “MT Center Gauge & Doweling Jig”. It seems like a really cool jig, but the order deadline was Nov.11, 2019. With any of these tools, you don’t exactly have a lot of time to think about ordering one, before it becomes EXPIRED. Weirder still is that the expired tools are often still on display on retailers websites. Is this some cruel way of saying “hey, see what you missed out on?”. Talk about rubbing it in your face.
I grew up using the metric system, where millimetres (mm) are the base form of measurement. Now, in Canada I live in a quasi-metric world, where “officially” metric is the system, but from a practical viewpoint imperial measurements rule, especially in the building industry. While at first I thought inches were somewhat archaic, to be honest as a woodworker, I prefer imperial over metric. I should point out here that there is no right or wrong, everyone has their own preference.
Imperial measurements are a throwback to another time, and north America is one of the few hold-outs. Although having said that, the worldwide airline industry still uses feet as the measurement of choice when designating altitude, and the nautical mile is used as the unit of measurement by all countries for air and sea navigation. Canada uses a bi-measurement system largely due to proximity to the US. Most wooden products bought here are specified in imperial, and grocery stores often sell produce by pounds (with kg also indicated). But why use imperial measurements?
I am sure from a scientific point of view, metric is better. Liquid measurement for baking makes more sense in millilitres. But that’s mostly because in the kitchen there is rarely need for measuring things down to the ml. Baking using grams also makes more sense, but then there are digital scales to do the heavy lifting. In the metric world, the divisions are millimetre, centimetre and metre, although the latter two never really seem to be used from a measurement perspective, i.e. you don’t see 137mm expressed as 13cm/7mm. In some places they even specify building specs using mm.
Measuring in inches
In metric we start with the millimetre, add ten of them together and you get a centimetre – 100cm gets you a metre. The problem with metric is divisions, or rather the lack of them. I think a mm is too small a measurement, and cm is too close to that. Add too many mm together and the number gets too big. In imperial there are inches, and feet which are conveniently different enough to be useful. Larger numbers can be broken down into smaller units. Smaller values are easier to remember, and deal with. Of course there is the decimetre, equivalent to 10cm, but hardly used. European cookbooks will often use decilitre to signify ml, e.g. 3.6dl instead of 360ml, but some things don’t seem to translate even within measurement systems.
Measuring in mm
From a woodworking perspective, 1mm is a tiny unit, akin to 1/32nd of an inch, which from a tolerance perspective may be too small. I tend to work only to 1/16th inch tolerances, so while 1mm may be even more precise, I wonder how relevant that is. How fine is too fine? How many woodworking projects need that level of precision?
At the end of the day, sometimes imperial measurements are just easier to visualize. My house is 14 feet wide, which is easy to visualize, because one foot is easy to visualize. 168 inches is less easy, and 4,267mm, not so much. You can measure roughly what a foot is, so you can approximate distances – doing that with metres is not as easy. There are some companies that make what are termed “engineer’s scale” tape measures, which use a decimal scale, i.e. divide the inch up into tenths. A good example is the Stanley Powerlock “Engineer’s Scale”.
working by hand 