Machine heads.

Machine heads. No, we are not talking about a Deep Purple album, but possibly the most important item on your guitar or bass.
What is a machine head? Well, some folks just call them tuners, tuning machines, string tensioners, winders...and a whole lot more. Proper terminology.....machine heads.
Why? Well, that is because that is exactly what they are, and what their sole purpose is on the instrument.
The machine head is usually made up of two gears that mesh together and drive the shaft that the string is attached to. One gear is a worm style and the other is a helically machined spur gear. The tuner button shaft, or 'input' shaft drives the worm that in turn drives the spur gear.
The tuner button is usually driven onto a splined shaft to avoid slippage, and keep the machine positive at all times.
Years ago, the machine head consisted of what is similarly used on violins to this day. The tuners were hand cut dowels, that were tapered and usually made up of a very hard wood such as ebony. These were installed into tapered holes, and the string was fed into this tuner by means of a slotted peg head, again, quite similar to todays classical (nylon string) guitars and violins. One would simply turn the tuner until the string had reached the desired pitch, then they were pushed into the taper to lock the string in tune.
This didn't serve to work too well with the guitar, because as string designs changed, it became more difficult to both tune the string and maintain that it would stay in tune.
Hence the machine head. Based on the old 'leverage' principal, turning the tuner shaft against the spur gear proved to be less of an effort, they maintained (well...sort of maintained) their tuning, and did it with a lot less effort.
When I mentioned they 'sort of' maintained their tuning, well, let's just say they have come a long way since back in the day. String tensions were greater back then than what they are now, due to the fact most of the strings were bronze wound steel core strings. And the core wires were huge in comparison to what they are now. So, a lot of times the guitar machine would slip back on the tension that was applied to it. One would literally watch the guitar tuner turn backwards while they were playing. And this didn't just happen to the old Silvertone's, Kay's and Harmony guitars, but also to the Gretsch's, Gibson's and Martin's as well.
How did they get around that? Simply by 'building a better mousetrap', or so to speak.
They had to redesign the early machines from their original gearing that was a 4:1 ratio, and increased that to an 8:1 gear ratio. They also cut the teeth on the spur gear on a slight angle, opposite to it's direction of travel. This helped in reducing slippage and back-lash on the gears.
Though standard machine head gearing has increased again to a 16:1 ratio, other improvements such as pilot shaft clutches help to reduce string slippage and increase tuning accuracy.
What is the best tuning machine out there today? Well, that depends on what you are looking for. One might want accuracy and not care about style and looks, while another might want the whole package.
There are many to choose from, such as Grover, Kluson, Sperzel, Schaller, Waverly, Gotoh, and so many more. There are also some really good machines that won't break the bank, like Profile and Planet Waves, and some companies even make their own machines, Fender and PRS to name a few.
My personal favourite is the Schaller machine for electric guitars and basses, and I would have to say Gotoh for acoustic guitars. Why? Well simply because, like so many other things that are made in Germany, they seem to out perform most, if not all of the others in some way. Schaller's 2030 Locking Machine is by far, one of the best on the market today, and with the inclusion of their new 18:1 series, you will have to go a long way to find a better machine. These are a little expensive, and can be harder to find than most, but they are worth the extra dollars.
Gotoh is a Japanese product, and for acoustics, and some electrics, such as the Strat and Tele, these machines are hard to beat. They are reasonably priced and will last for years. Like the German's, the Japanese also know how to build a very competitive product.
Now some of you like to look into modifying your instruments, and that usually starts with the electronics and bridge components.
Personally, I say do yourself a favour and start with the machine heads. Get yourself a set that will fit your guitar's original design. You should never have to re-drill holes or add screws. Your new set of machines should be completely interchangeable with the original set. Don't modify your guitar to fit the machine heads. You will only de-value your instrument and you can really mess things up if you are not sure of what you are doing.
If you are not sure of what to do, seek out someone in your area that is knowledgeable about this, and together I am sure you can weigh out your options.
I didn't talk specifically about guitars equipped with the Floyd Rose tuning system, and there is reasoning in that. The reason being, that will be something to talk about next time.
So, until then....stay tuned!!
Cheers!

Brett McNaueal