As a puzzle box maker, I'm finding myself more and more working to engineering tolerances. I spend more time with calipers in my hand than a rule. Recently, I added a set of setup blocks. What are setup blocks, you ask? They are very accurately sized steel blocks of common sizes, such as 1/6", 1/8", 1/4", 1/2", 3/4". As you can see here ...
Each of the black blocks is accurately sized - I checked them against my calipers and they are good to within .0001. The block that they are sitting on is called a 1-2-3 block. In each dimension, it is either 1", 2", or 3" and it is also just as accurately size. With all these blocks, you can make a wide variety of different measurements.
How would you use them. Actually, very easily and probably much easier than most other methods. Lets say you want to set a stop block on your table saw exactly 2 1/4" inches from the blade. You could make a mark on a test piece, but it, measure, then adjust the fence this way or that until it's just right. Or, you could grab your 1-2-3 block and the 1/4" spacer, put them by the blade, slide up your stop block and clamp it down. I like option 2. And, when I worked, I found the accuracy of the cut piece outstanding. Just remember to remove the blocks before turning on the saw!
Here's another common task - you want to set the depth of a plunge router cut, say for making a recess. You could set the router so the bit is plunged flush with the surface of the workpiece, then with a square try to set the plunge distance of the bit or you could scrounge around for a scrap piece the thickness you need to set the plunge stop. An easier way, set the router on a flat surface, plunge it till it touches the surface, then loosen the plunge stop, grab a spacer of the thickness you need, put it in your plunge adjuster and lock it down. Once again, another very accurate job.
What else? Lot of things (for which I didn't grab pictures). Set the height of a router bit at the table - just stock the blocks and adjust to bit to the same height (it's easy to feel when they are the same). Set your router fence, select the right blocks and position them between the bit and the fence. Lock in a dial caliper width - measure the right setup block and lock down the calipers.
Where to find these blocks? I got these from Lee Valley. You can probably find others via web searches or Amazon as well. The set I received was well machined and I know Lee Valley stands behind their work. Most places that sell metal working equipment will likely have these as well. Sizes of sets can vary.
Want to adjust to even smaller distances? Get a set of feeler gauges (automotive stores have these) and you make changes down to .0001 inches. Yes, you can accurate and easily set of a cut at the table saw to 2.0001 inches.
What am I doing when not setting things to tight tolerances? I am wrapping up the latest set of puzzle boxes - which I have now decided to call "The Button". The amount of work needed is greater than I imagined, but they are moving along nicely and I hope to have at least 2 out of 5 done in the next 1-2 weeks. I have plans for a set of simpler puzzle boxes in my head and I'd like to get moving on those as well. Plus there's a crazy new customizable cipher machine in the back of my mind that needs some time at the drawing board. We're in the peak holiday season, so it seems I'm losing part of every weekend to a party as well.