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...simple, by keep the after lengths parallel to the head stock plate to reduce the leverage on the tuning posts. Which means paying attention to the head stock angle and the height of the posts with no play in the post holes and tight fittin bushings.

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Countersink the tuner holes after finish? Removes enough finish around the hole to keep the bushing from hitting it.

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Chris

because of the resolution of the image I'm not getting a totally clear view of what's going on...

what I'm seeing appears as follows:

holes were drilled before finish

because edges of holes were not eased, the sharp edge resulted in the finish building up there (actually not on the exact edge, the finish flowed away from that sharp edge)...this buildup of finish is what is actually cracking and causing what you are experiencing...in a nut shell the finish appears to be too thick in that area...

then again I could be completely off base...

'duh ... dead simple.

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Audiences and dispensations on Thursdays ~ by appointment only.


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That could conceivably also be cause by over tightening.

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Old growth, shmold growth!

Maybe use stepped holes............???
Tom

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A person who has never made a mistake has never made anything!!!

Maybe try stepped holes..................??
Tom

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A person who has never made a mistake has never made anything!!!

Just to rule it out... you did use vinyl sealer between ebony and nitro, right?

I could see where if the front and back of the headstock were not parallel (the top of the head is thinner than the base) that could be the cause as well.

Interestingly enough the only time this happned to me was when I used vinyl sealer under satin nitro.

I removed it all and reshot gloss laquer over bare wood.

Done that ever since, no problems.

I should mention that I use the gotoh delta 510 tuners almost exclusively. They have zero capstan play, at least initially, and so should present little to no capstan tilt if solidly mounted. So I strongly suspect poor adhesion and overtightening to be the problem in my case.

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Old growth, shmold growth!

One thing you didn't mention, what type of tuners and bushings? When did the delaminations happen? If some time after striniging that would indicate the holes were a bit too loose. But I have seen this with press in bushings where the hole is too tight. press them in and everything is fine , a day or so later ....POP. This has happened to me before strings were put on, it took me a few test panels to get the holes just right for the bushings.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Maybe try stepped holes that are countered sunk for the washers.......???
Tom

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A person who has never made a mistake has never made anything!!!

Maybe your lacquer isn't burning into your sealer?

Stop putting strings on your guitars!

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David Morris

The problem is caused by the (over-tight) washer embedding in the finish then rocking forward under string tension as the capstan moves in its clearance hole.

If you use a stepped hole of the right size (Goldilocks), leave the finish to harden and don't tighten down any more than just snug, you shouldn't get a problem.

If you've drilled 10mm diameter right through, some 10mm OD, 1mm wall aluminium tube (easy to get here, maybe harder where you are) can be used to bush the upper part of the hole so that when you screw down tight on the ferrule the washer seats on the alu bush just touching the finish.

Spot facing can be made to work, but there are easier solutions.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Chris, I think (as mentioned) that stepped tuner holes ready help. I've had the same problem with a variety of finishes, stepped tuner holes solved it completely. Stewmac sells lots of bits for that purpose. Smart cookies, them...

clearly this is a disadvantage of a tapered headstock. Are there any advantages?

The effective "tilt" due to tapering works out at less than 0.5 degrees . It wouldn't help, but anyone drilling by hand would be lucky (or very good) to get that close, so I think the the over-tightening and tilting of the post under string load causing the washer to slide are the main contributors. I've never measured it, but my guess would be that post tilt under load is a lot more that 0.5 degrees, especially on budget tuners. I've seen the bubble problem on un-tapered headstocks, where students have been rather too enthusiastic. The ali tube trick should still work for Chris. Just leave the tube a smidge longer, and don't snug down the bushings until at least a little string tension has been applied. The washer will pull over a little as the post tilts (a little) but won't ruck up the lacquer in front of it as it's not embedded in it.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Might have been covered already....but chamfering the edges of those holes and then sanding those edges to a smooth radius PRIOR to finishing will go a LONG way to prevent the lifting of the finish as depicted.

And then....using a tapered reamer through the back of the headstock that has a taper reasonably close to that of the tuner sleeve (if any), and being careful to create a slightly snug fit will keep the tuner from moving in the hole. The right fit means that the tuner cannot press ALL the way into the headstock but rather, requires the tightening of the nut on the headstock face to make it seat the last 1/8" - 1/16" of the way. If you make a really nice, tight fit of the sleeve to the hole...there will be very little stress at the headstock face.

And then....the best stick I've found is epoxy pore fill followed by vinyl sealer (thanks Todd) and a nitro topcoat...at least when using nitro for a topcoat. Optimizing adhesion will alleviate some of this issue here, and in another half a dozen places on the guitar.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Chris: Think you just answered your own question.............!!!
Tom

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A person who has never made a mistake has never made anything!!!

That works out to 0.51 degrees.

I guessed at tan (1.6/200), 1/16"=1.6mm and my headstock blank is 200mm. Works out to 0.46 degrees. Near enough for jazz. I'd venture to suggest that not too many drill press tables are set up to better than half a degree (especially if just eye-balled off the scale).

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Chris: I was speaking about the taper. Todd has expanded very well.
Tom

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A person who has never made a mistake has never made anything!!!