Fifty years is a long time, particularly in the life of consumer good. Fifty years ago transistor radios were trendy, color TV (showing three national TV networks!) cost as much as a car, and the portable gadget to wow your friends was a Kodak Instamatic camera with a flashcube.

The few things I have that have passed a half-century or more come in two categories. Either keepsakes like photos of my ancestors or my father’s Army medals. Or tools. Virtually all of them hand tools, because there is nothing wrong with a century-old hammer or screwdriver. (And if they haven’t broken yet, they’re not likely to.) But I do have one curiosity. An old electric hair clipper.

It was given to me “for parts,” but still looked and worked well, so I kept it in one piece and used it for what it was designed for. (The paradox of cutting one’s hair very short is that one needs to cut it more often to keep it looking decent, so I do it myself once every few days.) It worked great for years—until it stopped. (In the middle of a trim, which is a whole other story.) I took it apart and found that it was older than I had thought. On the inside of the cover was a list of relevant patents. This is pretty common, but was interesting was that someone had engraved these numbers into the original mold by hand, in steady engineer’s lettering.

A little detective work showed the most recent patent date was 1962. Of course it could have been made any date after that, but it wouldn’t have had any significant changes without additional patents.

It took a bit more detective work to find out what was wrong, but in trying to fix it, I broke it. (sigh) All I needed to do was give a plastic screw a turn, but it had either sized up, or become brittle (or both) and crumbled when I applied a bit of pressure. Out of curiosity, I did look for a replacement part, but the manufacturer wasn’t selling a plastic screw for a 50 year old piece of equipment.

However, the new products on their website looked very familiar. And they went out of their way to point out that it was “Made for use in USA electrical outlets only. Not for international use.” which made me wonder how much had really changed in the last fifty years.

Trimmers like these work by having one set of toothed blades slide back and forth across a fixed set. Hair (and anything else) that gets caught between the teeth is cut as the first set moves. It’s simple and works well, the only trick is generating a good, powerful oscillating motion. Cheaper clippers (which I’ve also taken apart) generate this with the spinning of a simple electric motor with a cam on the end. This works well enough, and uses mostly off-the-shelf components. But there’s a lot of friction on the cam which is a problem. It saps power from the motor, tends to make a lot of noise, and (because hair is highly abrasive and gets everywhere) it tends to be the primary failure point in these clippers.

These old clippers work differently, with much more power and less troublesome friction. Knowing that they only work on American outlets was a clue as to how, as was the noise it made when it was working: a familiar 60hz hum. (Also, I’d taken it apart already, so I cheated.)

Knowing that the previous model had worked for (off and on) 50+ years, I decided to get the latest model from the same manufacturer. I was curious about how the design had evolved since Kennedy was president.

From the outside the differences look pretty superficial. I’m glad to see a more robust cord and polarized plug, but both are required for a modern device get a UL listing. The switch lever looks like it might come from the same mold, though the color is different. And the blades look very similar. But the cases are clearly from different molds. Are the more or less similar inside?

The screws holding the faceplate have decreased from three to two, and they go through the other side, but they’re the same self-tapping screws in both. Same Phillips head, same diameter and length, same thread pitch.

And the mechanism in the interior is virtually identical.

The way it works is by utilizing the 60Hz oscillation of AC power to run an electromagnet. AC power inverts the polarity of the electricity 60 times a second. When you use this to run an electromagnet, it effectively turns it on and off every time the power alternates. In the clipper, the electromagnet is the big orange thing near the front, wound with all of the copper wire and a C-shaped ferrous core that’s fastened securely to the case. The motion is created by the vaguely question-mark-shaped piece of metal on the right side. It’s only attached at the base of the unit near the cord with two beefy screws. (The cover in the 2016 version blocks access to the screws from the outside, which seems fair. Unscrewing them without opening the case would be bad. But they also made them pentalobe screws, which means they don’t want owners touching them.) The straight part of the question mark is a very sturdy flat spring, which attaches to another C-shaped (or rather Ꜿ-shaped) block of metal at the front. Below that (unseen in this pic) is a little knob of Delrin that guides the blade. The metal block is what the electromagnet moves, and the spring is powerful enough to move it back before the next cycle, 60 times a second. It only moves a millimeter or two, but that’s all it needs. There’s no loss of efficiency converting rotation to lateral motion, no extra friction. Electromagnets can be incredibly powerful, and the only parts to wear out is the spring, which is incredibly robust and will wear slowly due to its limited motion. (And the blades, but even they use wear as a mechanism to sharpen themselves.)

If it’s so simple, what stopped the old one from working, why haven’t I talked about those two coil springs, and what’s with the plastic screw I crushed?

Sadly crushed plastic screw, lower center-ish.

The reason this model says it’s only for North America is that the entire thing is tuned like a tuning fork to the North American household electrical supply of 120 Volts and 60Hz. (Different countries/regions have different voltages and frequencies.) At a different voltage the magnet wouldn’t pull it the right distance, and at a different Hertz it would fight against the spring’s natural vibrational frequency. The plastic screw is there to provide fine tuning by adjust the dampening effect the two coil springs have on the main spring. If your household voltage runs a bit low (which is sometimes a thing), the magnet won’t have quiet enough power to move the lump of metal in proper tune. Turning the screw will move the metal end slightly toward (or away) from the electromagnet, controlling the influence of the magnet. Over the last fifty years, something had changed inside my old trimmer, either the magnet’s power faded or the springs slowly weakened. Turning the little plastic adjustment screw would likely bring everything back into working order. But it was brittle and broken. For want of a nail, the shoe was lost, etc.

Unfortunately, the new model also has a plastic screw, though this time it’s a Phillips head instead of a straight head. I’m not sure that’s an improvement. It will spread the turning pressure over a larger area, but I didn’t strip the head, I shattered the body. At least it’s probably a different plastic formulation. Plastics have come quite a ways in fifty years.

Old on top, new on the bottom. The little yellowish plastic T (or ╡) near the front of the clipper is what transmits the motion to the blade.

Except for the plastic case, most parts are interchangeable between the two models. The blades in the old model are better finished and feel like higher quality steel, but I didn’t test it empirically . The new floating blade has two holes and a bevel but don’t seem to do anything for this model. (I suspect they’ve been added so the blade will work on a different model.) The fastening screws are Phillips in the new model vs flat head in the old(which is an improvement), but they’re the same size and pitch. Attachments from the old one work on the new one.

Brand new blades on the left. Fifty year-old blades on the right. Which look newer?

There are a few small changes inside. The switch is different, but I can’t really say if one is better than the other. The old one is enclosed so I can’t see what it has going on. On the other hand, the new one is exposed and hair trimmings can get into the main body. (Somehow since there were some in the old one when I first disassembled it) So having the new switch open to possible hair interference seems like a step back. Power to the electromagnet is now attached with crimp and push connectors and no longer has adhesive glommed on to hold everything in place. This seems like a good improvement, but really only from an ease of manufacturing side. The durability should be about the same.

So that’s what you get when you go from 1962 to 2016. It’s rare that there are so few changes over such a long time. The patents covering the main mechanism expired decades ago, so any other manufacturer could make an identical one, and it’s not very complicated. But clearly there is something to be said for a design that stands the test of time.