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Mike Floorstand |
Here's a bunch a photos taken during my latest project: replacing the friction tuners with geared tuners on an old tenor banjo. In my (limited!) experience friction tuners are just about OK on nylon-strung instruments but steel strings add so much tension so either the tuner spins back or you have to tighten the tuner screw so much that the tuner can't be turned at all. These are the tuners to be removed:
First step is remove the screw which holds the button in place. Careful not to lose the washer!
Next remove the button itself. Mine were a bit stiff.
Once the button is removed, the spacer/friction washer just slides off.
Once the washer is removed the shaft can be removed from the string side of the head.
The remaining tuners are removed in the same way. The main problem as mentioned above was the buttons were often quite stiff.
Here are the disassembled tuners. Each tuner just has four parts (five if you count the washer on the screw). The button shaft is rectangular with two flat and two curved sides.
The width of the shaft according to my (not very accurate, but with a deceptively reassuring digital display!) calipers is 5.3mm.
The new tuner to be fitted has a shaft diameter of 7.5mm (7.3 according to my calipers, I told you they were rubbish!). The tuner is from ABM (model 4201) with 4:1 gearing; purchased from Thomann for 85 Euro (for four tuners) plus 10 Euro shipping to UK. There are eight parts to this tuner (excluding the parts inside the gear housing); my initial thoughts were I will need to be careful to put the washers back on in the right order, but actually the button and all the washers that it holds in place do not need to be removed - only the nut washer needs removing before installation. The button shafts are square so I can't fit the old button on these new shafts (not a big deal, though the old yellow buttons perhaps complement the aged maple neck better than ivoroid).
The shaft holes on the headstock will therefore need to be enlarged to fit the new tuner shafts. This requires a special tool called a reamer, and I found this one on ebay. It is described as a violin peghole reamer with a 30:1 taper (from 3/16 inch at the tip to 21/64 inch at the top, i.e just less than 5mm to just over 8 mm, so perfect for this project - not so good if you are fitting a tuner with the more common 10mm shaft). The ebay seller was Peter Kessler from Canada and I paid USD $27 plus $10 shipping to the UK. This is what a reamer looks like:
I put some tape around the reamer at what I measured to be the 7.5mm diameter to make sure I didn't ream the hole too big. The tape needed moving a couple of times once I got close the final hole size. This is the reamer at the beginning of the job, inserted into the hole left by the 5.3mm friction tuner shaft:
Here we are a little over halfway, now reaming from the back:
I alternated reaming from the front and back. Nearly there now!
Almost done!
Finally, one of the tuners can be pushed, snugly, into the newly reamed hole:
Different angle. You can't see it very well but there is a small spike on the gear housing which will pierce the headstock and prevent the tuner body twisting once the tuner nut is tightened. I thought I'd be able to manually push this spike into the headstock but that was too hard - I did wonder if I should create a hole for the spike with some other tool but in the end just gradually tightened the shaft nut until the gear housing was flush with the back of the headstock.
Reaming is quite slow (took me maybe 10 minutes for each hole, though I was going slowly and checking whether the new tuner shaft would fit yet quite frequently) and makes your arm ache! But finally all four holes are now reamed to the right size.
From the back. Note the first string hole (bottom right) is quite close to the edge of the headstock. This could be problem if the diameter of the tuner gear housing had been any larger.
The side edge of the gear housing is just about flush with the side of the headstock on the treble side:
Here's a shot from the other side, you can see there is a bit more clearance between the edge of the gear housing and the side of the headstock on the bass side:
One final shot from the front of the headstock:
Hope this helps someone - thanks for reading!
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