Special Thanks to Dave Slusser for providing this article.


Installing tuning machines on a neck not drilled for THOSE machines.

Recently I was asked to build a Bass guitar for a guy. Not an odd request, except that after I acquired the neck, I found that it was pre-drilled and the holes were too small for the type of tuning machine that I was using.

The client asked for a particular type of machine and I had to ream the holes (photo 1) and plug (photo 2) and re-drill the screw mounting holes. If youíve ever installed tuning machines without a locking nut type of top threaded bushing (photo 3), then you can imagine how difficult it would be to hold the tuner, the bushing, the square, and the drill bit needed to mark the hole locations all with only two hands.  The biggest problem is getting the bushing to stay centered in the string post hole.

As a technique, when I drill tuning machine holes I always drill them about .010Ē larger than they need to be., After all, you WILL gain about .008Ē for lacquer. So, if the hole is basically the correct size BEFORE you spray the finish, well, after you are done and youíve gained .008Ē for finish, youíll need a hammer to get those tuning machines and or bushings in the wood. This is NOT a good idea on a great finish !

Now back to the subject. First get some cheap masking tape. I use the painterís type that is labeled as being low tack. Take a strip of it about three times the circumference of the tuner or bushing and cut it in half length wise. Now wrap one half of it around the bushing just below the top trim collar, (photo 4) thatís the part that sits on top of the headstock. Next, trim any tape off that sticks below the bushing (photo 5) so that just the part that sinks into the wood has tape around it.

Now try to insert it into the headstock and see if it fits snugly (photo 6), but NOT too tight. Basically youíve just centered the bushing in the hole and stopped it from dropping out. If it does drop out, add some more tape and try it again.

Once you have the bushing and tuner in place, get a spring clamp like the one in the photo (photo 7). Orient the tuner to about the correct spot and place the clamp on the back side of the tuner or mounting plate and clamp it.

Now take a square (I use a small machinistís square) and slide carefully down the edge of the headstock and against the tuner plate to square it up to the headstock edge (photo 8).  What I normally do is use a drill bit the same size as the mounting screw hole, push it lightly through the hole and rotate it backwards with my fingers (photo 9) to make an impression in the wood. 

Once youíve done this, you can remove the clamp and the tuner and go repeat the process for the first hole in each of the other tuners. Remember -- DONíT mark out any more of the holes in that plate without the bushing and one mounting screw in itís place ! After youíve drilled the first mounting screw hole reinsert the bushing, put in the mounting screw, double check your alignment with the square, THEN mark the rest of the holes (photo 10).

 Beware -- if the bushing isnít in place you have NO way of knowing if the string post is centered in the tuning machine hole. 

After youíre done with the first hole repeat with the other three, four, five, or six depending on what youíre building.

I hope this helps someone... Happy building .

Dave Slusser
Summerhill Studios

Photo 1

Photo 2

Photo 3

Photo 4

Photo 5

Photo 6

Photo 7

Photo 8

Photo 9

Photo 10


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