Official Luthiers Forum!
http://mowrystrings.luthiersforum.com/forum/

Vintage 1930's style Martin belly bridge dimensions and...
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=55566		 Page 1 of 1
Author:  jfmckenna [ Thu Mar 09, 2023 12:47 pm ]
Post subject:  Vintage 1930's style Martin belly bridge dimensions and...
Does anyone have the specs on this bridge? In particular the width of it at the widest point. I'm building some Style-45 OM's now that were originally intended to have pyramid bridges which are narrow we have decided to go with the Belly bridge of that time period instead and I need to know if it will fit on the bridge plate. This is a last minute decision.

I've always striven to make the bridge plate about 1/8th in larger then the bridge. The OM's I am building now are at 35mm.

Also what are your opinions on the original vintage shallow angle compensation design of the saddle slots? My client favors that for it's original looks but I'm not to keen about struggling with getting the intonation on it right.

Best regards.
Author:  Darrel Friesen [ Thu Mar 09, 2023 8:08 pm ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
Not sure about vintage, but the one Stewmacs one I have is 37mm.
Author:  Clay S. [ Thu Mar 09, 2023 8:35 pm ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
jfmckenna wrote:
Does anyone have the specs on this bridge? In particular the width of it at the widest point. I'm building some Style-45 OM's now that were originally intended to have pyramid bridges which are narrow we have decided to go with the Belly bridge of that time period instead and I need to know if it will fit on the bridge plate. This is a last minute decision.

I've always striven to make the bridge plate about 1/8th in larger then the bridge. The OM's I am building now are at 35mm.

Also what are your opinions on the original vintage shallow angle compensation design of the saddle slots? My client favors that for it's original looks but I'm not to keen about struggling with getting the intonation on it right.

Best regards.


I don't know any of the original dimensions of the bridge, but TJ Thompson might have something on his site. As to making the bridge appear to have a shallower compensation angle you could make it slightly more than the vintage angle, then angle the bridge itself slightly and add a little nut compensation to bring things back to what is needed. Small "tweaks" might not be noticed.
If your customer likes a low action, having a shallower angle compensation design might be O.K. , especially if he values looks over proper intonation.
Author:  doncaparker [ Thu Mar 09, 2023 9:31 pm ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
Just an observation you could share with this client: in my almost-60 years on this planet, when I have made choices based on looks over other virtues, I have almost always regretted it.
Author:  Woodie G [ Fri Mar 10, 2023 8:08 am ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
The 1934 000-18 shade top the boys restored was for all intents and purposes a late 1933 OM, with Martin apparently burning through left-over OM parts (long scale, bar-fretted boards) prior to the shift to the eventual shorter-scale 000-18 production and T-frets in the summer of 1934 (please correct my memory if short scale was a bit later... I cannot find my notes, but recall initial 000-18/28 was long scale). A few historical facts gleaned from various sources, to include some discussions and a measurement session with the Martin Museum and Custom Shop folks:

- Martin began using the belly bridge in April 1930; this bridge had very little compensation... the boy's measurements showed something like under 0.020"... almost nil.

- According to Mr. TJ Thompson, saddle compensation increased to nearly 1/16" by early 1931 and to a full 1/16" by the end of 1932 (see his notes on the 1930's belly bridge he offers).

- By early 1934, saddle compensation had increased further to the modern measurement of closer to 3/16"

Every instrument has a back story by the time it has been played for 50, 60, or upwards of 90 years, and 'borrowing' a back story from an actual 1929-1933 OM that saw later T-fret conversion, bridge replacement, and tuner swap might create a plausible rationale to bring your customers around to a configuration which will likely improve their playing experience.

So here is where some story line editing comes into play:

First and foremost, if your OM replicas are more 'in the spirit of...' with modern T-frets, it seems silly to force yourself to use the inadequate saddle compensation of 1/16" given other departures from strict OM orthodoxy.

So it seems like you have some options:

- For slavish adherence to a configuration representing the post-April 1930 period, pair those bar frets you have installed with 1/16" saddle compensation bridge.

- If you have already opted for T-frets, it is quite reasonable to suggest that the reason for those modern frets and full compensation on the bridge on a 'vintage' guitar would have been a Martin factory conversion done in the later 1930's (board replacement for T-frets and bridge swap to get better compensation).

- From the http://www.vintagemartin.com site, "While all Martin guitars built in 1929 were made with rectangular or pyramid bridges, a number of Martins from before 1930 can be seen with original looking belly bridges, which is the cause of some confusion. Due to slow sales from the depression era economy, Martin still had a number of unsold instruments with serial numbers stamped in 1929 remaining in their factory for another two or three years, many of which were still unfinished, without bridge attached, or "in the white". Martin fitted these with belly bridges before they left the factory, and additionally asked dealers to return unsold guitars which they retrofitted with belly bridges to ensure that they were strong enough to hold steel strings."

- So quite plausible that an OM held in Nazareth or unsold in a dealer shop might have been built in 1929-1930, then modified to belly bridge configuration with modern compensation.

On conversions, it is interesting to note that nearly the entire production run of the 1930-31 OM-18P (plectrum banjo long scale bar fretted neck on OM-18 body) saw conversion to six string configuration. So it seems reasonable to play a bit fast and loose with initial factory configurations to provide your customer with a more useful instrument, given the economic effects of the Great Depression on Martin;s production and sales and professional musicians going through the shift from banjo to guitar at the end of the 1920's/early 1930's.

Finally, if you do go with full modern compensation, the guys would like to suggest that you consider the fact that the pin holes on the earlier belly bridges fall in the middle of the bridge - about 11/16" back from the front edge - versus what appears to be a 0.040"-0.060" or so shift to the rear as seen on later belly bridges. That full modern compensation creates a bit of a challenge re: fitting a ramped and slotted solid pin on the low E with acceptable string break angle at string height at saddle over about 0.450" on an 11/32" thick bridge. Moving the pin line back helps keep the break angle below 45 degrees.
Author:  guitarjtb [ Fri Mar 10, 2023 8:31 am ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
Great info Woodie, as always.
Thanks
Author:  jfmckenna [ Tue Mar 14, 2023 1:31 pm ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
Thanks Woodie and all. These are definitely 'in the spirit' of and player guitars. I want them to have the vintage Martin sound but they have my bolt on neck with a two way truss rod too. So they are not replicas in the full sense of the word. But the 'skin', the looks, are the 45-style.
Author:  Clay S. [ Tue Mar 14, 2023 5:08 pm ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
99.99% of the people who see the guitar will admire the bling and how it sounds and not ever think about the angle of the saddle.
Author:  Woodie G [ Thu Mar 16, 2023 4:44 am ]
Post subject:  Re: Vintage 1930's style Martin belly bridge dimensions and.
Along those lines, sneaking the through saddle slot back about .025", cutting the slot another 0.010"-015" deeper, and pushing the pins back another .050"-060" over vintage practice will make for a healthier bridge. Having replaced a half doxen or so bridges that failed at the treble side, Martin's design can be improved with minor impact on appearance. Yes - we reproduced the vintage bridges on vintage guitars and made sure they were glued in to a perfectly-fitted slot with 192g, but on the custom builder versions, we felt unconstrained in fixing what we saw as 'they should have known better' stuff.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/