Okay, here’s one of those annoying articles of mine, where I do quite a bit of thinking out loud. My last few postings were all fairly well polished, so I think I’m entitled now to at least one intervening stream-of-consciousness narrative.
Some of you are well aware of my intense fascination with square nails. I mean, what historian-preservationist-craftsman wouldn’t be? In fact, it will be two years ago next month that I’d published “Yes, Virginia, They Really Do Still Make Them“, my seminal article about the history of square cut nails, and the evolution of their modern equivalents, on Building Moxie.
Many folks don’t realize that traditional square nails are still manufactured today. In fact, they’re even available in bulk quantities. Historically accurate reproductions are still often hand forged by blacksmiths, but most machine-cut nails are mass produced by the Tremont Nail Company, in Mansfield, MA, using 125+ year old nail cutting machines.
Can these modern, machine-cut nails rightfully be called “historic reproductions”? Well, they certainly can be used in that capacity. But I think it’s more the case that they represent the current state-of-the-art in the technological evolution of the square cut nail. Although made on the same nail cutting machines used over a century ago, that machinery has been retooled to cut nails from steel, not iron. So modern square cut nails are stronger and less brittle than their iron ancestors. They’re also available in a number of different finishes (e.g., black wrought, hot dip galvanized, bright finished).
Anyway, it’s my place to futz about with these different variations of modern-traditional nails as much as I care to. And this afternoon, I did just that. Using one of the test assemblies I’d created in my recent evaluation of two 18V cordless drills (another Building Moxie submission), I extracted all but two deck screws from each of two end boards, replacing them with wrought and rose head galvanized square cut nails, respectively.
Why do this? Well, I was curious about how common sizes of pressure treated, dimensional lumber might react to these nails. Granted, I was nailing into a preexisting screw hole, but good enough for now (or so I thought).
What did I find? Well, several things.
The key to driving square nails is to ensure that the longer edge of the nail shank (which actually is more rectangular in its upper portions, than square) is parallel to the grain of the wood it’s being driven into. (The nail in the above photo is oriented in this manner). This ensures the shank cuts the wood fibers, pushing them downward like a small wedge, and with minimal chance of splitting the board.
But the wood grain of the “joist” beneath the board runs at 90 degrees to this ideal orientation, forcing the nail shank to cut across the grain. Now, if the joist were, say, a 4×4 or 4×6 timber (as in many old timber frame homes), no big deal. But in my test assembly, it’s a 2×4. So invariably, the square nails caused each 2×4 to split slightly, despite the presence of the “pilot hole” left behind by the extracted screws (it might even be the case that this facilitated the splitting, since the existing hole didn’t afford the nail an opportunity to shear the wood fibers; so, instead, the nail just pushed the walls of the hole apart — maybe).
Also, I didn’t care very much for how the rose heads settled on the surface of the board, despite the fact that I’d intended to face-nail them, in the first place. The wrought nails were fine; their heads are fairly large and are expected to remain above the wood surface. They also completely covered whatever hole was left by the previous screw heads.
However, the rose heads are slightly different. Their shanks “mushroom” outward just under their heads, just like a conventional exterior wood screw, with the intent of cutting and spreading apart the wood fibers so as to slightly countersink the head. And the rose head also has a small, reverse dimple (I call it a “hobnail”, although this isn’t an accurate term) that’s supposedly decorative, but actually offers a surface to the hammer, and can enable the rose head nail to be countersunk, without the hammer over striking the wood surface.
My less than ideal results in naturally countersinking the rose head nails I attribute simply to the fact that there was already a round screw hole there, and this didn’t afford the rose head mushroom much opportunity to properly cut and push apart the wood fibers. I also didn’t like the fact that the hammer ever so slightly flattens the very top of the dimple (plainly obvious in the above photo). I’m not sure how to prevent this, other than to wrap the hammer head in felt (maybe). It’s not significant, but still obvious. And I just don’t care for it.
What’s next? I’ll try repeating this experiment with some clear deck boards, and clear 2x4s and 4x4s (one can never have enough test jigs laying about, anyway ). I’ll also try it with galvanized square-cut common nails, which have flat heads and somewhat thinner, sharply angled shanks. This might prevent the underlying 2×4 from splitting. I’d also like to see, much longer term, how the galvanized steel weathers and reacts to the pressure treated lumber. That’s about it for now!