Pattern for bridge for bowlback

[Brian T]

Just won an e-bay auction for a Ditson Empire bowlback mandolin. It is missing the bridge and I would like to try my hand at making one. Does anyone have drawings or even measurements that they could share? Any help would greatly appreciated.

[Eugene]

Congrats, Brian, and welcome to the fold. A great many firms, with differing bridge patterns, built for Ditson's house brand. #Can you post an image or two of yours? #I'm sure many on this board could come up with good detail images of a great many bridges.

[Brian T]

Thanks, Eugene. #By all indications from the pics, the mandolin is a Martin style 1. #I do not have any pics but I think you can still view it on E-bay. #It is item number: #3721203170. #I will be aable to tell more about it when I get it in hand. #It was shipped UPS on Monday.

[Eugene]

I just looked. Congrats. It looks simply elegant. Will you be tackling the top cracks yourself too? Frankly, I'm not certain who made yours, but the construction looks more Vega-like than Martin-like to me. The profile, headstock joint, and clasp all strike me such. If it is a Vega-made piece, it's possible it would have been built for the bridge to rest behind the cant (the top's crease). This was a quirk of many of Vega's quality pieces. It's hard to tell from the images, but from what I can see of the original bridge's footprint, it looks to have been seated right on the cant! I think I would hold off on bridge fabrication until the piece is in hand and you can measure the scale length to determine where the bridge should rest. For bowlbacks, I think Vega made some of the very coolest American bridges, but I'd bet they also are probably the hardest to reproduce.

[Brian T]

I received it! It may be Vega. I haven't measured it, but the marks indicate that the bridge gested on the cant. The top cracks are straight, clean and will glue back together really nicely. (I'll be doing them myself). There is also a separation between the ribs on the back. I need to do some research on the Ditson Empire model mandolin. My book on Martin guitars by Mike Longworth says that Martin built 45 Empire mandolins between 1915 and 1916. I'll keep you posted on what I find.

[Luthier]

This is one I made for someone last year but I can not seem to locate the measurements.

Don

[Brian T]

Thanks for posting the pic. I think it will be a big help. I have a friend that is a very good luthier. Maybe he can help me get the measurements correct. I'll keep checking.

Brian

[Eugene]

For good measure, here's a typical example of Vega's behind-the-cant bridge design. #The bone/ivory saddle is seated in a trapezoidal, open-faced groove in the ebony frame. #There are no notches in the saddle; it serves only to set string height (and transmit vibration, of course). #To change action, you simply change the saddle to one of a different height (or modify the existing saddle). #String spacing is kept by deeper-than-necessary slots to the rear of the ebony frame; the slots can be cut very deeply because they have nothing to do with string height.

[Eugene]

...and on ID, check out the back-of-head images of Martins in the bowlback thread (http://www.mandolincafe.net/cgi-bin/ikonboard.cgi?act=ST;f=15;t=14185). If a bowlback of this age doesn't have some incarnation of the classic Martin "V" volute
(either reduced for a single tuner plate and back-of-head veneer or in whole for paired tuner plates), I would wager it is not a Martin.

[Brian T]

You may be right. It does noit have a volute of any kind. But, Martin built Ditson instruments to Mr. Ditson's specifications and even used his (Ditson's) serial numbers on the earlier ones. I sent martin an e-mail request about their records on instruments that they built for Ditson. Will just have to wait a bit now.

[Eugene]

One more thing on Martin bowlbacks. By this date, Martin had slid the soundhole a couple cm to the south in order to accommodate a full 20 frets requiring no fingerboard extension.

...And one more thing on Vega mandolins. Check out the slight violin-like volute behind the Vega headstocks (also on the bowlback thread linked above). This is what strikes me as most Vega-like about yours, Brian. This was not ubiquitous, but was a feature of all the better-than-entry-level Vegas I've seen. Vega also used a scrolled ornamental hole in the headstock very similar to your Ditson. For what it's worth, I would argue that the finest bowlback produced by an American firm was Vega's Pettine Special model.

Gruhn's book describes the instruments Martin built for Ditson, including bowlback mandolins. Unfortunately, I'm in the office and away from such reference. I seem to recall they did not differ significantly from a few of Martin's production models. If they did in decor, rib numbers, etc., they would not be likely to in profile. Martin would use forms to shape the bodies, and building different forms for the small number of mandolins Martin built for Ditson wouldn't seem to be practical. For example, Martin also built the style 6a for a specific retailer. While the decor is a custom kind of period style 3 X 6 hybrid, the profile and proportions are identical to the rest of Martin's mandolin production.

[Brian T]

You are most likely correct. In any case, the mandolin is a very nice piece and I got it at a killer price. I think that it will be a very nice sounding instrument. How clsoe would the measurements from a Vega Cylinder back bridge be to fitting the bowlback?

[Eugene]

I'm not certain. I believe they were similar, but the cylinderback bridges might be a little higher than the bowlback bridges. Does this sound right, collective knowledge?

[grsnovi]

Measured off my Vega Style 4.

All dimensions in inches.

Base is ebony, saddle is ivory.

http://hometown.aol.com/garyguitars/vegabridge.jpg

[Brian T]

That's great! Thanks for the drawing, Gary. That's just what I needed.