Before fancy modern geared tuners were invented, acoustic guitars, banjos, fiddles and other stringed instruments were tuned by friction tuners. The friction tuner was all pickers and fiddlers had for many years. These days there are many varieties. Newer versions are much more sophisticated. This article explains a few interesting details about a very old style of friction tuner.
The image below shows the component parts. The tuner looks like a giant, but it is actually only 2 1/4 to 2 1/2 inches long when assembled on the peg head. The grip is about the size of your thumb. Well, that is if you have fat thumbs like me. This set came off a mini-tenor guitar made by Harmony in the early years of twentieth century.
From left to right in the above image are the tensioning screw, grip, lower friction barrel with cone, tuner post with upper cone.
The image below shows the knurled barrel and tuner post assembled. The barrel slides on the tuner post shaft. The tuner post (right end) stands proud of the peg head face. The barrel goes in the back with the cone towards wood. Note how there are two cone shaped areas pointing to each other in the middle of the tuner shaft. Depending on adjusting screw tightness, these cones grip the peg head and allow the tuner post to stay where you want it for the desired string tension. Of interest to me and probably no one else is why did they knurl the barrel thereby adding to unit cost? You can’t grip the knurling. It serves no purpose other than decoration. Feeble minds wonder at such things.
The image below shows an interesting detail about the relationship between the grip and the barrel. These two areas mate and are seemingly intended to work together. However, there is no reason for the teeth. The grip rides on the square shaft of the tuner post. The grip will turn the tuner post with and without teeth on the barrel. The grip actually does not care weather the barrel rotates or not. So now we have two mysteries in the interesting world of luthiery: knurling and teeth. The adjusting screw must be just tight enough to make the friction cones grip the peg head. Plenty of trial and error are required to get the tension just right. Don’t oil any of the parts. Friction is critical on all mating surfaces.
The image below shows a modified mini-crow bar. I used a Dremel tool to widen and shape the hook end. You can see a curved area where there used to be a narrow slot for pulling mini-nails. The tool is 5 1/4 inches long and is the smallest size made. Use a modified tool like this to pry the barrel off the tuner shaft, thereby forcing the grip to pop free. Pay attention to where the parts fly off.
In many cases, the grip is frozen on the square tuner post shaft. It has to move up and down with the barrel according to tensioning screw tightness. This is the first and most important thing to check on an old set of friction tuners. You may have to pry the barrel away from the tuner post shaft (after removing the screw) so the grip can move up and down. Do not pull or pry on the grip. It is very fragile. No worries at all if the teeth on the grip are ruined. The tuner will still work. I often wonder why guitar equipment designers design as they do. You might say I have a very bad case of day dreaming.
The vintage tuner can work well if in good condition and properly tensioned. Patience is a virtue here.
Any way, the first three rules of all luthiery work should be evaluate, evaluate, evaluate.