I was once like you. I never imagined one of the most useful, versatile, and inexpensive tools in my workshop would be a 2-pound steel rectangle. Yet I'm here today, folks, to spread the word! I'm here today to proselytize my belief in the 1-2-3 block. I'm here today... to convince you.
Yes, the amazing 1-2-3 block (also written 1 2 3 block or 123 block) was a recent addition to my growing collection of random wood / metal working tools. Originally designed as a machinist tool - and still marketed as such - its utility goes far beyond use in machining.
I discovered them quite by accident - while looking around on Amazon for a women's Victorian-era working-class lace-up high-top leather shoe (with heel). I sometimes have very specific tastes when it comes to fashion. And no, I never did find a shoe I liked (*sigh*). Anyone who uses Amazon with any regularity knows that the website likes to offer suggestions of products you might like to spend money on. For me, this is usually a pretty random collection of items: western women's wear, powered speakers, shoes (of course), varnish, razor blades, bras, Edison bulbs, and (for some reason) 10 pound boxes of modeling clay. It was in a list like this one that the 1-2-3 block made its first appearance.
The pictures were not particularly exciting. There were multiple versions of the blocks - some with holes and some without holes. Otherwise, they looked like metal bricks. An apt description, actually. They do have a certain brick-like quality (especially the blocks without any holes in them).
Honestly, I don't know why I clicked on it. I'd never heard of a 1-2-3 block before. I think I was simply curious. Or bored (you know how it is late at night, surfing Amazon - knowing you should head to bed, but too zombie-like to stop staring at the computer).
Once I clicked on the image, I was quickly lost in the wondrously-particular, highly-polished world of precision metal blocks.
I should probably mention something important here; I have something of a fetish for measuring tools (squares, levels, bevel gauges, tape measures, etc.). This stemmed from a desire to be able to cut lumber (and other materials) as precisely as possible. A cut made with a saw is only as good as the fence calibration on the saw itself. That is, if your saw is slightly off - you might be cutting a very small angle into every cut you make. Generally, one small miscut isn't too big of a problem, but when ALL of your pieces have small errors in them - then you get a terrible example of the power of compound error. Many small errors add up to big errors.
Thus, I'm always looking for better ways to 'square' my saws and other tools. To 'square' something means to ensure there is a 90-degree angle between something (generally a saw blade) and something else (generally the base of the tool). I'm always acquiring more and better measuring tools to help me with this.
Unfortunately, simply buying a new measuring tool (i.e., a square) doesn't ensure squareness because the new tool might be slightly off (maybe it was dropped at some point before you bought it). It's a special hell when you can't trust the 'squareness' of the tools designed to help 'square' other, bigger, tools. Tape measures have the same problem - how do you test a new tape measure when you suspect your other tape measures are off?
The end of this madness is a specially padded white room - hopefully with square corners - but how would you know?! The moral of this story is you have to find a comfortable point to settle at (before 'padded white room' time). While I still have a basic mistrust of all my measuring tools (and the 'squareness' of all my cuts), the 1-2-3 blocks have gone a long way towards easing my mind.
A 1-2-3 block is a metal block machined to be precisely 1 inch by 2 inches by 3 inches. Since machinists are the primary users of these tools, they have to be very, very precise. Machinists work with super-small tolerances. For example, they might cut an important part for an airplane engine on a metal lathe that has been calibrated with a high-quality 1-2-3 block. If a piece of wood for some furniture I'm building is slightly off - no big deal, but if said airplane engine part is slightly off... You get the idea.
The blocks typically come in two varieties - with holes (one or more) and without holes. I tend to use the blocks without holes, while the varieties with holes are more often used by machinists. Machinists use the holey variety for some kind of mystical, magical purposes having to do with bolting things to other things while chanting ancient machinist prayers (I have no idea what the holes are for - I'm not a machinist. Google it).
The tolerances of the (admittedly lower-quality) 1-2-3 blocks I recently bought are .0001" to .0003" in size, and .0002" per inch in squareness. Higher quality blocks have even smaller tolerances. Generally, I'm not working with those kinds of tolerances on anything I'm building. If the table doesn't wobble, and the chair doesn't fall over - I'm happy. Of course, it is worth mentioning that wood is an organic material that changes shape as the ambient moisture levels change - so it would be pointless to try and build anything super precise (not a lot of wooden airplane engines out there).
While I'm not a machinist - the obvious utility of the 1-2-3 block as a calibrating tool quickly occurred to me. Theoretically (and as I discovered, actually), the blocks could be used to check 'squareness' on almost all of my measuring tools / devices. They can also be used to directly calibrate big tools (like saws). The blocks could even be used to check the accuracy of a tape measure. When tape measures go bad - usually from being dropped - it's typically the metal tip that gets messed up. Hooking a tape measure to a 1-2-3 block will show you if the project you built sucks because all your measurements were 1/16" off due to a bad tape measure (which is pretty much the worst thing in the world).
The blocks are reasonably heavy - around 1.5 lbs per. This may not sound like much, but the weight is very compact - and makes the block feel heavy for its size. This weight means I can use the blocks to weigh things down while I'm gluing pieces of wood together. Glue is my primary mode of attaching pieces of lumber, and not all pieces can be clamped together with traditional methods (and I don't have time to stand there and hold a glue joint together for 30 min until it starts to dry). Since the 1-2-3 blocks are smooth and precisely square, I can use them to hold joints in the proper shape and apply pressure at the same time - a win-win. The blocks are also useful for holding down curling edges of drawings or paper rolls. They have been so useful for these purposes (and others), my original collection of 2 blocks quickly grew to 8 - and I wish I had more!
Thankfully, the blocks available on Amazon are fairly inexpensive - less expensive then any other measuring tool I've ever purchased! When new, 1-2-3 blocks have a light coating of machine oil to prevent rust. I had to wipe this oil off (so as not to get oil on my projects), and the bare steel will rust easily - so be careful how you store your blocks (don't get glue or moisture on them).
While they might seem like small, heavy, metal bricks (one might even say 'boring') - the uses for them as a workshop tool are only limited by your imagination. I always have my modest pile ready to go - and I'm always reaching for them for one purpose or another, regardless of the project.
Uh oh. I just learned there is such a thing as 2-4-6 blocks! I'm off to Amazon... ;)
-Lia
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My Writings (Transgender Woodworker content)
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My Writings (Transgender Woodworker content)
Artfully Functional (my studio)
LiaZero.com (all my online content)