Just because its new tech doesnt mean that its better...

I saw a very interesting program on the History Channel this weekend that proved a point I had attempted to put forth in other threads (notably the thread regarding new combat weapons being better, and I am still waiting for proof of the new generation weapons superiority over what we had 50 years ago): That point being, if it ain't broke, dont fix it!

This point revolves around some of the oldest construction technology that humans possess: Nails.

The first iron/steel nails were hand forged and were of square cross section with a wedge shaped point. Because they were hand forged, there were relatively expensive and time consuming to fabricate.

On the face of it, it seems like a lot of work to make something you are only going to pound into a couple of pieces of wood to join them together, but considering that it was the first true method of constructing buildings, it was pretty high tech at the time when they were first used.

Modern nails are much cheaper and much more quickly mass produced. In modern nail manufacture, a spool of heavy guage steel wire is unwound, and fed through a hole. As the tip of the wire protrudes through the hole, a hydraulic hammer smashes the tip, flattening it, forming the nail head. The wire continues to feed through the hole until the desired length is reached, then hydraulic snippers cut it and grind the needle shaped tip on all in one step. A single nail machine can manufacture more than 1000 nails a minute.

OK, you say, that is a technological improvement, going from one at a time hand forging to automated mass production. That is true.

But how well do they compare in terms of performance? Here, it gets interesting.

When you look at the mechanics of how nails actually work at holding wood together, the two different nails work very differently. The modern round nail, with its needle shaped tip essentially pushes the wood fibers apart and forces itself between the wood grain. The wood fibers attempt to regain original shape and orientation, and compress on the nail at right angles to the direction of the wood grain. The nails holding strength comes from the friction exerted by the wood fibers on the sides of the nail, which turns out to be around 45% to 55% of the total surface area of the round nail.

The hand forged square nails of old, with thier wedge shaped point actually penetrates and cuts the wood fiber. As it is driven, the wood fibers not only compress on it at right angles to the wood grain as above, the broken wood fibers expand longitudinally and compress on the nail parrallel to the wood grain, exerting compressive friction on all 4 sides, 100% of the available surface area. Also, considering that a square nail of the same diameter as a round nail has an additional 25% surface area, the holding power of a nail manufactured almost 200 years ago is actually 2.5X greater than that of the same sized nail manufactured today.

Just because its high tech doesnt mean it gets the job done any better (and quite frequently not as well as) the old technology.