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Old 02-01-2021, 01:50 PM
lkjjr lkjjr is offline
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Default Replacing slot head style tuners on 1972 Martin D35S

I am looking to replace the tuning machines on my 1972 Martin D35S with slotted headstock.

The OEM Grover tuners on this guitar employ a “step down” shaft design with the shaft having a diameter of approximately 1/4” as it passes through the outer portion of the headstock that then steps down to approximately 3/16” for the remaining portion of the shaft where the string wraps and where the shaft rests in the center of the headstock.


thanks to John Arnold for correcting the sizes...
Quote:
Your numbers are off. The Grovers have a 3/8" boss, and 1/4" shafts.
All the more up to date tuning machines I’ve bee able to locate all have straight 3/16/ inch shafts. Looks like to properly mount any newer/more modern tuning machines will require a bushing/spacer that seats the shaft properly in the outer portion of the headstock.

Anyone have experience with this sort of issue or suggestion on sourcing an appropriate busing.
Thanks...


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1972 Martin D35-S
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Last edited by lkjjr; 02-01-2021 at 03:24 PM. Reason: correct sizes
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Old 02-01-2021, 02:02 PM
John Arnold John Arnold is offline
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Your numbers are off. The Grovers have a 3/8" boss, and 1/4" shafts. Most modern tuners have a 1/4" or a 6mm shaft. Some people install Stew Mac 3/8" conversion bushings, but I prefer plugging with mahogany and redrilling, since it is less weight. I actually turn the plugs on a lathe and drill the hole at the same time, to assure the holes are perfectly centered.
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Old 02-01-2021, 02:40 PM
lkjjr lkjjr is offline
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John, thanks...

You are right, I got the numbers wrong, thanks for the correction. Love your method of using a lathe to turn precise inserts for this application. Unfortunately I don't have the equipment (and this late in life maybe not the skills) to give that a go.

I'm hoping to be able to do some sort of "drop in" conversion that I can easily "undo" if I ever want/need to put the originals back.

Appreciate you taking the time to weigh in.
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Another Gray PickerYouTube

1972 Martin D35-S
2007 Larrivee LV 05e
2017 Cordoba Fusion Orchestra CE
2021 Alvarez AP66ESHB Parlor
2020 Fender Special Custom Telecaster FMT
2011 Custom built Vintage “Strat”
198? Electra X930 Vulcan
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