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I'm stumped... I SHOULDN'T be , but I'm stumped, and I don't know why.

I have small pilot holes drilled at the appropriate place on my headstock. The thing is I CAN NOT find anything that is the CORRECT bit diameter.

with my digital calipers the BACK part of the tuner (the enclosed tuners) reads .392"

the TOP side of the tuners (the part that SCREWS INTO the larger diameter) reads .303"

I'm assuming that the top is drilled smaller than the back and they meet in the middle.

So what am I missing...are these readily available wood bits that I just can't put my hands on at the shop for some reason or do I need a specialty tool to make this happen.

Thanks for any help on this...

There isn't a 0.392" o.d. / 0.303" i.d. (adjusted a bit for clearance) bushing as part of the installation, maybe?

If not, I guess you would have to step-drill from the back side, 0.303" through then a 0.392" recess drilled to whatever depth required.

As far as drills....look at the letter-size drills. An "N" drill is 0.302" and an "X" drill is 0.397".

Or 7.70mm is 0.3031" and 10.00mm is 0.3937".

This link might help: http://www.stewmac.com/How-To/Online_Re ... artin.html

I understand what your saying, however I can't be the only person to install these tuners haha. I mean they come with the martin kit so they have GOT to be fairly widespread.

I have done it two ways. Usually I drill a small pilot hole all the way through and drill from both sides with the correct diameter bits. I also have just drilled the smaller shaft hole and used a reamer. stewmac sell some specialty bits as well.

Would a standard reamer work from HD ?

If 'twere me I think i would drill through 0.392" and make (if I couldn't buy) six bushings to press in the top.

Do the closed Martin tuners screw together instead of having pressed bushings? (my suggestion was for pressed bushings) If that is the case drill a 10 mm hole and screw on the head stock bushing and be done it.

Well there are 9.9 mm bits readily available :/

the closed tuners , the busings are threaded and screw into the housing

correct.
I think i got it handled.