I'd venture to say that 99% of gear replacements happen unnecessarily. Players perceive a malfunction (worn, stiff, won't hold tune, whatever) of the gears, and decide to replace them to solve the problem. But the problems are in fact simply a matter of needed maintenance and adjustment, or an issue with the instrument that has nothing at all to do with the gears. It's usually either 1) the points of friction at the nut and bridge need attention, or 2) the gears themselves are not properly maintained. Boy, do I wish I could get those discarded tuners back, for they're usually way better than the replacements people put on instead. Eighty years and counting, those old Gibson/Vega/Martin/whatever gears have a long way to go yet, if only the players would get with the program. But so many people would rather just spend money on some fashionable consumer item that's being advertised. Blah blah.
Let's look at making the gears themselves work right. The discussion of friction at nuts and saddles can be pursued by clicking here.
By the bye, I do see tuners poop out completely: cracked cogs, slipping gears because teeth are worn down or tolerances were lost - all due in some measure to poor maintenance, though most such problems arise in cheap or shoddily made gears. There used to be really low-end machines made entirely of steel that never seem to work in right, no matter what you do. They look like this:
Yes, this is a snakehead Gibson A-Jr, which is where I seem to see these gears the most often. Steel plates, cogs and worms: they are really difficult. It's worth trying the procedures below, but they may only be partially effective.
However the more common old Waverlys, even when worn visibly, work great because they were very well made in the first place, and that bit of brass in the cogs and the plates really seems to help. Terminal problems with them are very rare.
Fortunately, if all else fails, Stew-Mac has some very high-grade tuners available now that have a vintage appearance that fits most of the old mandolins.
So let's assume the worst about just the gears and look at the stuff you might have to do to get those old Waverlys, or whatever you have, working like new. If they're really stiff and normal string tension doesn't take the play out of the gear, as it should, and they look bad and seem encrusted, it's time to do the big 100,000 mile overhaul.
Hopefully you won't need to do this, but it happens sometimes: to get stuck cogs off the posts, you may need to use (or make) a tiny pin punch that will seat at the bottom of the screwhole inside the shaft but won't possibly touch or damage the threads. Here's a pin punch:
Put the gear plate on a good vise whose jaws are closed almost to the diameter of the shaft, but not tightened to it. Just a hair loose. This way there is full support for the plate and the cog, but room is left for the shaft to drop through between the jaws of the vise. (A hole in a very hard block of wood would do as well.)
Put the pin punch down the screwhole until it touches bottom, and tap gently with a hammer. The gook holding it all together will give and the post will drop through, hopefully landing where you can find it again. Then you have the whole thing completely apart and can clean every bearing surface, so the cogs and posts all turn cleanly.
2) Clean the face of the cog that actually contacts the plate, and of course clean the plate too. Use an old toothbrush, a bunch of Q-Tips, paper towel, and patience. Several cleaning agents come to mind, naphtha (lighter fluid) being near the top of the list. Naphtha will dissolve the petro-derived plaque that creates quite a drag on the gear parts that should be able to make normal contact and slide smoothly. Get rid of it. You want everything clean and shiny.
Naphtha won't hurt the finish or the buttons. Or you, as it's not particularly toxic. It's sold as lighter fluid, but it's much cheaper at paint and hardware stores. It cuts the stuff, wipes dry and leaves almost nothing behind, and what does get left behind can be cleaned with a typical water-based household cleaning agent, although it's not essential. Not sure what you'd find in your local store or under your kitchen sink, but Simple Green or 409 are two very good products.
Get the metal completely crust-free, then polish these surfaces with a good metal polish such as Flitz or Simichrome if you wish. It's most important to simply get the surfaces clean and smooth.
Once the cogs and shafts are clean and dry and shined up, they'll slip right back together.
4) Clean the screws that hold the cogs on. Completely. And again, use a screwdriver on them that fits the slot precisely, so you don't booger it up. Nothing worse than a boogered screw slot, I say. The old American-made ones are a 4-36 thread, and you will not find this screw at any hardware store.
5) Clean the insides of the headstock bushings. Q-Tips work well for this. You want them clean and shiny inside. Do those in place, you don't need to remove them. Unless, of course, you want to do a number on the face of the headstock. Here's your chance to clean and polish everything.
Next, there's what is known
as dry
lube available
at
bike
shops the world over, which I was told was even better,
because it
contains the PTFE but no oil
at all. PTFE is the lubricant, it's a dry
sphere
too small to see. It's in a carrier which evaporates.
The "dry" stuff looks like
this:
I came to discover it did not work well. One bottle just congealed and hardened into a rubbery solid sitting on my shelf, another headed the same way and wouldn't even squeeze out. Phooey, I went back to the so-called "wet" formula.
Whatever you do, do not use any common lubricants like WD-40, Three-In-One, sewing machine oil, 30-WT, Caramba, or anything like them. Not Vaseline, nor hi-tech greases, nor Mazola. I also briefly used a dry lube called Finish Line and saw the entire bottle polymerize into some dreadful gook in a matter of months. Avoid this product, it's the same as the dry Tri-Flow, and it's not much good.
OK, we can consider the following to be basic tuner maintenance for any gear, as long as they're reasonably clean.
8) You need to tighten the screws that hold the cog just right. They need to be tight enough to hold things together, but loose enough to be able to yield to the pull of the string when it's at tension. If you overtighten it, the cog will bind on the plate, even if it's clean and polished and lubricated. This is the trouble many people have: they overtighten the screws so the cog is hanging up and there's no backlash movement in the gear. It must be able to move smoothly when up to tension. If a knob turns but the cog doesn't, this adjustment is wrong, or it's still dirty. Tighten it snug and then back it off about 1/19th of a turn.
OK, it must be said: backlash is good, it's necessary, it's unavoidable. Make it work for you by maintaining the gears. The string tension will pull against it fully, if the gear is adjusted right.
When you install strings, or just to work the lubricant into an unstrung gear, use a string crank:
Here's one of my favorite shop tools, which I had to make:
Standard little electric screwdriver, it takes a standard hex drywall bit which is elegantly bonded to a beheaded Scotty. This has been my standby for 25 years. You can do a lot of turning with this, especially in a power drill!
If the bearing surfaces are clean, polished and well lubricated, and if the screw adjustment is correct, these gears will turn smoothly with no knob play under tension. The strings take up the backlash if they can.
And it goes without saying, but I'll say it anyway, you always tune up to a note. If your string is sharp, tune below and then back up to the precise pitch. Right? Right.
And another thing: there are other structural issues with gears that will compromise their function that cannot be mitigated with lubrication or screw adjustment. If the gears are lubed and adjusted properly but are still difficult to turn, even without strings on, or if the gears turn well under no load, but seem to almost seize up as they get closer to pitch, the post spacing may be wrong relative to the spacing of the holes in the headstock.
Here's a way to make a new set of Klusons for
mandolin out of single Kluson gears for guitar.
These are four of six commercially available
tuners made for Fender headstocks.
You have to shorten the plates a little more to make
the shafts align properly with the holes.
The buttons are a little large, but they work OK.
This isn't a 100% solution, but it may have to do
until something better comes along.
At the moment there's no 4-plate Kluson-type
mandolin gears, unless you find some on eBay
on or off an old instrument.
Note the little hole in the housings - it looks like
a letter O in the word Kluson. These are for lubing
the gears. Do it, it really helps.
More mandolin gear stuff such as mandolin gear direction here
Information about new and old Gotoh mandolin gears here
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