Official Luthiers Forum!

This top was pulled off a 1931 Martin OM 28. There was old work done on it by the factory at some point and the plate was changed. The original plate was 1 3/8 inches wide . I could measure that off the notches in the X braces. The bracing was all notched and the transvers brace is .325 wide .650 high the X braces are .312 by .625 , tone bar and finger braces are .250 wide. The width is 15 1/16 without the binding , with the binding it was 15 3/16 inches.
Look close at the rosette , that is different to the modern . Enjoy

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Oops! Picture disappeared

Back again and even more!!!

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Joe Beaver
Maker of Sawdust

Very infornative John. Thanks for posting

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Joe Beaver
Maker of Sawdust

Cool. Those braces look very hand carved
What's the white ring around the sound hole?

Rosette picture didn't get posted

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Joe Beaver
Maker of Sawdust

Thanks for posting John. That looks like a pretty big bridge patch...

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Very interesting, John! Thanks for sharing these.

That's a big bridge plate! Brazilian rw?

Buffing compound, I'd say.

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jw ( o)===:::

Thanks for posting John.
There is nothing quite like having the guitar apart to get the real info.
It does make you wonder why Martin builds modern OM's with 1/4" X-bracing, since none of the originals I have measured were so equipped.

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John

Double post.

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John

Too cool. Gotta ask though, why was it pulled?

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Brian

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

https://www.howardguitarsdelaware.com/

structural issues and it is getting converted. The top is cracked at the neck block and the damage at the plate makes this a prime candidate for a 45 conversion.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Rosette
here it is

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

How did it sound with that gigantic bridge plate?

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Thanks, John,

did you measure the thickness of the top?

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We are all in the gutter but some of us are looking at guitars.

My 1930 OM-28 had similar damage, but I chose to save the top. That is in spite of the fact that there is no original top left under the bridge. No one who has played the guitar could detect anything abnormal or substandard about the sound. The key is the parallel grain red spruce patch, which performs infinitely better than any oversize bridgeplate, especially a rosewood one.





I used a similar spruce patch underneath the fingerboard. The UTB had previously been replaced with a 1/2" wide brace, but after installing the patch, I installed a 5/16" wide brace like it had originally.

The top is reasonably flat, and the guitar was strung with medium strings for over 10 years with no change in the action.



The marks around the bridge were from an oversize pyramid bridge which was on the guitar when I bought it. The 'bridgeplate' was 3/8" thick Douglas fir plywood, at least as large at the rosewood plate in John's photo.

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John

I agree the top may have been salvageable but the customer wanted to have this converted . The top was also thinned when it was refinished at the factory sometime in the 70's. Since the guitar was not in original condition with the refin , replaced bridge and pickguard , it was a good candidate for conversion.
I won't destroy a guitar for conversion unless it had already been altered.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Thanks John! (and John!) Any idea what those crisp looking rosette rings are? 10/20/10 B/M/B? plastic in the middle?

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Pat

actually the rosette is made from Black wood fiber , maple and according to the Archive , the inner white was a plastic no longer available called fibroid and I think it was a brand name , and may have had a acetate base. I use ivroid for the off white appearance. I do get the "vintage" rosette material custom made.
inner and outer rings are the same .010 blk .015 maple .030 blk .015 maple .010 blk
inner ring
.010 blk .015 maple .030 blk .040 white. .010 blk .040 white .030 blk .015 maple .010 blk

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Make you feel good when they use the "good stuff" for a repair.