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Documented 1931 Martin OM 28
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=36574		 Page 1 of 1
Author:  bluescreek [ Wed May 23, 2012 12:04 pm ]
Post subject:  Documented 1931 Martin OM 28
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
Author:  Joe Beaver [ Wed May 23, 2012 12:07 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Oops! Picture disappeared

Back again and even more!!!
Author:  Joe Beaver [ Wed May 23, 2012 12:12 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Very infornative John. Thanks for posting
Author:  Quine [ Wed May 23, 2012 12:32 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Cool. Those braces look very hand carved
What's the white ring around the sound hole?
Author:  Joe Beaver [ Wed May 23, 2012 12:37 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Rosette picture didn't get posted
Author:  sdsollod [ Wed May 23, 2012 12:42 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Thanks for posting John. That looks like a pretty big bridge patch...
Author:  CharlieT [ Wed May 23, 2012 12:56 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Very interesting, John! Thanks for sharing these.

That's a big bridge plate! eek Brazilian rw?
Author:  joe white [ Wed May 23, 2012 12:57 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Quine wrote:
What's the white ring around the sound hole?


Buffing compound, I'd say.
Author:  John Arnold [ Wed May 23, 2012 3:14 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
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.
Author:  John Arnold [ Wed May 23, 2012 4:12 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Double post.
Author:  B. Howard [ Wed May 23, 2012 6:06 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Too cool. Gotta ask though, why was it pulled?
Author:  bluescreek [ Wed May 23, 2012 6:25 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
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.
Author:  bluescreek [ Wed May 23, 2012 6:27 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Rosette
here it is
Author:  klooker [ Thu May 24, 2012 6:48 am ]
Post subject:  Re: Documented 1931 Martin OM 28
How did it sound with that gigantic bridge plate?

Kevin Looker
Author:  Joe Sallis [ Thu May 24, 2012 7:13 am ]
Post subject:  Re: Documented 1931 Martin OM 28
Thanks, John,

did you measure the thickness of the top?
Author:  John Arnold [ Fri May 25, 2012 11:27 am ]
Post subject:  Re: Documented 1931 Martin OM 28
Quote:
The top is cracked at the neck block and the damage at the plate makes this a prime candidate for a 45 conversion.

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.

Image

Image

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.

Image

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.
Author:  bluescreek [ Fri May 25, 2012 1:03 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
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.
Author:  Pmaj7 [ Fri May 25, 2012 1:54 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
Thanks John! (and John!) Any idea what those crisp looking rosette rings are? 10/20/10 B/M/B? plastic in the middle?
Author:  bluescreek [ Fri May 25, 2012 5:45 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
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
Author:  Clinchriver [ Fri May 25, 2012 7:38 pm ]
Post subject:  Re: Documented 1931 Martin OM 28
John Arnold wrote:
Quote:
The 'bridgeplate' was 3/8" thick Douglas fir plywood, at least as large at the rosewood plate in John's photo.


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