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The Tuner Hole Blues

Total Topics: 1
Total Posts: 1
There have been a lot of Guitars built by the posters and lurkers of this site and I do not recall ever seeing this issue addressed. That being, the chipping of the finish around the tuner holes. This has been a chronic dilemma of mine regardless of material. Ebony on mandolin's and Banjo's, Rosewood's on Guitars, etc. The tuner holes are reamed with the step reamers and then champhered slightly top and bottom. Then I normally sand to 400 grit, clean with Acetone, pore fill, lay on a couple light coats of Vinyl Sealer, and start my nitro build. I like to use the vintage open back style of tuners and they have small bushings with no washers. So there is very little room for error. When it comes time to clean up the post holes after finish, prior to tuner installation, the finish lifts off of the head wood. If I am lucky enough to get the tuner holes cleaned up without chipping, then chances are it will lift when I press the bushings in. Is it possible I am getting the wood surface too smooth at 400 grit? It appears not to separate from the sealer but rather from the wood thereby leaving those dreaded white blisters under the finish. I have experimented with different finish thicknesses but it did not seem to make a difference. I used Sherwin Williams for years and have switched to McFaddens for the last couple of guitars thinking this might be an issue but the results are the same. I spend almost as much time cleaning out the voids and drop filling with all the leveling, etc., than I do with the rest of the finish job. This problem is kicking my butt so I come to all of you for ideas. Thanks in advance.

May 21, 09 | 9:07 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
The way to avoid that problem is to machine a counter sink for the tuner washer. You need a drill press for the process I use. Clamp a piece of wood to the DP table. Drill the 10mm size hole into the wood, glue a short piece of 10mm dowel rod in the hole. Now you chuck a 1/2" center cutting end milll in the drill press. set the back of the headstock on the dowel pin. Set the depth of end mill to make a shallow cut into the headstock veneer. That's it --- the pin set up will automatically center the end mill over the tuner mounting hole in the headstock. With the counter sunk hole there are no more worries regarding the tuning machine washer blisterring the finish.


Kenneth Michael Guitars est. 1978

May 21, 09 | 12:29 pm

Total Topics: 1
Total Posts: 1
Thanks for a great idea Ken.

May 22, 09 | 5:27 am
Ken Hundley

Total Topics: 40
Total Posts: 2169
I had an issue with splitting....I won't use those tuners anymore. I just don't like them, but every time I tried to press the bearing, the wood would split just a little...even countersinking or enlarging the hole didn't help.

May 22, 09 | 10:00 am
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
I use a similar method but use a sharp brad point drill bit. Also cutter speed is important. Too slow can grab and too fast can heat up. I also do pre drill my holes before finish. That way when the finish is still uncured I can chamfer the edges and a taper will clean out the hole.
Good center cutting mills are great tools. I also had split issues on the bushings in my early days and found this method helped me. I use a tapered reamer and clear the hole so that the bushing just bites the edge. I use elmers glue press and clean up. The glue isn't there to glue in the bushing but to fill in.
I have used this for 8 years and never had a split since or lost a bushing.
john hall

Blues Creek Guitars
Authorized CF Martin Repair Center

Jun 06, 09 | 3:16 am

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