Official Luthiers Forum!

I'm afraid I did something moderately stupid on my first guitar. Namely: go a little overboard in the bridge dimensions stakes. Because I liked the look of the thing. The thing looks like this:


It's significantly wider than a Martin Belly bridge, for one thing (6 3/4" vs 6"), as well as deeper (about 5mm, 3/8" more). The wings swoop in more, so the surface area's only very slightly larger (and the rear line far longer) than a martin bridge, but I'm worried the extra width, and the added crosswise stiffness it brings, in particular, is one of the reasons my first gutiar's bass isn't quite as full as I'd like it to be.

So my question to those in the know: opinions on this issue? Are these dimensions excessive? For those who don't build with straight-martin-copy-bridges, how close (in terms of width, depth, etc) do you stick to the martin dimensions 'box'? How long and wide are your bridges? The next bridge goes on a baritone acoustic, so the larger gluing area might be nice, but I'm not sure the extra crosswise stiffness is necessarily a great idea.

Mattia,

That's certainly a "fine lump of a bridge"

I prefer minimalist and love this one that Stefan Sobell made and put pictures of on his website:

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Thanks! I feel it'd look beter if I sloped the area behind the saddle, but, y'know, first bridge and all that.

I didn't have a scale at the time, so no, that one didn't get weighed (and I'd have little to compare it to, anyway). I've been perusing old MIMF discussions, and it seems I'm not too far out there in terms of size; several of folks seem to build them as deep as I do, most don't go quite so wide, though. Might downsize it to 6.5" wide (those wings are very thin) and keep the look, because darn it, it fits the rest of the guitar!

Mattia, I think that one of the few places one can truly 'play' in guitar building is the bridge shape. Your design looks really beautiful to my eye which can be enough reward in and of itself.

Tone wise, I am no expert and I am not expecting Scott to comment on the tonal possibilities of that particular shape, but it feels intuitively to me that the mass may be a bit much to get the tone into the sound board efficiently. Again just a sense, and it still looks beautiful.

Larry

_________________
Thank You and Best To All

Well, it's nicely done, and if the proportions work well with the whole of the guitar, use it!

A slightly heavier bridge will, all else being equal, lend to a deeper bottom end. It can also be countered by a lighter bridge plate..). While tough to do on this guitar, on your next one, if you really loove the looks and proportion sof this bridge, then consider making the bridge plate and area lighter to make up for the bridge. It all works as a whole, so if you ad mass upstairs due to a design criteria, take the mass off downstairs, so to speak.

You could(should) also consider making it thinner. 3/8" is a tad tall, and only leads to requiring a greater neck angle, which leads to more drop-off at the body, fitting problems, etc... Again, everything works as a whole, and everything affects something else.

I think it looks great! Id like to see it on your guitar.

Pictures! Of course!

_________________
Support the OLF! Bookmark our STEWMAC link Today!
Lance@LuthiersForum.com

[QUOTE=Mario] Well, it's nicely done, and if the proportions work well with the whole of the guitar, use it!

A slightly heavier bridge will, all else being equal, lend to a deeper bottom end. It can also be countered by a lighter bridge plate..). While tough to do on this guitar, on your next one, if you really loove the looks and proportion sof this bridge, then consider making the bridge plate and area lighter to make up for the bridge. It all works as a whole, so if you ad mass upstairs due to a design criteria, take the mass off downstairs, so to speak.

You could(should) also consider making it thinner. 3/8" is a tad tall, and only leads to requiring a greater neck angle, which leads to more drop-off at the body, fitting problems, etc... Again, everything works as a whole, and everything affects something else.[/QUOTE]

I think I'll leave it this size for the baritone (after reading some comments from Dave Berkowitz re: size of bridges, and I've only just noticed it's very, very similar to his. Heh.) I think I can refine the shape slightly and take off about 2-2.5mm off each wing, so almost 1/4", which will bring things down slightly. One of the next builds is going to be a parlour guitar, and this one's definitely too darn big for that.

What's a ballpark for a 'heavy' bridge, though? 35-40 grams? Rosewood ones in the 28-35 category or so? Be nice

How thin is 'safe', here? As low as 1/4"? I built this following basic dimensions from Cumpiano, and advice from, well, all over the place; I'll probably get with the fine-tuning of this one once I have another acoustic to actually play while I'm doing it! The next one's going have an ebony bridge (on a WRC top), so I'm thinking something less tall is a really simple way to get the weight down significantly. Might also feature an adjustable neck joint if I can get the prototype working to my liking..

Mattia, I love the design but just like Mario said, maybe you can make it a little thinner..... you can also make the same design at a smaller scale!
Just an idea!

Lets us see some pictures!

_________________
Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

I'd consider anything over 30 grams as heavy. Mine come in at under 20..., but I make up some mass with an African blackwood bridge plate. It has to be taken as a whole. For example, if you use a tiny maple plate, a 30-40 gram bridge could be the ticket. If you use a large rosewood one, then the bridge needs to go on a diet, and so-on...

Also depends a lot of the tone you're after. Keeping everything light lends to an airy, bright, seperated tone, adding mass lends to deeper bottom end, and more blending of the notes. lighter is more responsive, heavier is smoother, etc...

How thin depends on your box. Do you have a top radius? Did you add some angle to the neck block area of the top, how much drop-off do yuo want, etc... Only you know the answer to this one. But for the sake of giving you something to start with, yes, there are many bridges at 1/4" in height. I wouldn't go much lower, as you don't have much wood left in front of the saddle, but there are tons of old 1/4" tall bridges still in action.
Mario38758.4971527778

Peter: possibly, but downsizing too much leaves the wings very tiny, doesn't *quite* work. I'll be scribbling for a while.

Mario: gotcha. Your bridges are all fairly small (as in narrow, rectangular, no belly) affairs, right? As for tone, for this one I'm looking for something that'll respond to both fingerpicking and relatively light strumming (friend I'm making it for is an alt.country/old-timey/singer-songwriter type player/songwriter, likes to fingerpick, but does strum), but it's a Cedar top, so something that'll add a bit of 'sparkle' might be good. As for the whole dropoff, etc. well, the 25' dome+arched braces set the neck quite naturally where I wanted it for the last two, with minimal sanding of the sub-fingerboard area a la Charles Fox/Lance.

Thanks guys!

My first bridge, and probably next few started out as 6 1/2 long by 1 1/2 wide by 3/8 tall. After all the contouring and doing the wings, it came in just under 3/8 tall. I like it and I like the way it sounds. Mine is ebony. Go for it, it'll work!

Ron

_________________
OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Mattia--I think your bridge is quite handsome, and I for one don't object to longer lengths (wing tip to wing tip). Now the front to aft depth, well, might be a bit much. I'm thinking of your comment about lack of bass, and wondering if this is the guitar whose bracing you pictured a few weeks ago? I thought to myself at the time that the bracing looked a bit stout, and that might be more of the culprit than your bridge.
Just spekyoulaytin' here....

Steve

_________________
From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Mattia:
Your bridge looks a lot like mine, too, except I slope it back from the saddle more, so that the back edge of the bridge is the same thickness as the wings, and round off the top surface a bit more. One on my students years ago called it a 'Mazda Miata bridge'. Some of the variables:

Width (front to back)
This is probably the most important design factor in keeping the bridge from flying off and killing the cat. The maximum stress on the glue line is highest at the leading and trailing edges, and drops off in between to a value that is probably characteristic of the glue and maybe of the wood it's on. The point is that making the bridge wider cuts down on the max stress, since more of the total is taken up by the middle part, and it's the max stress that tells you how long it will be before the thing peels up. Note that a Martin belly bridge has a smaller footprint than most classical bridges, but holds up under the greater string tension.

Length:
A longer bridge stiffens up the 'wings' of the top by making the free span between the bridge end and the top edge smaller. This can raise the tap tones, sometimes by quite a bit, depending on the top and about a dozen other things. This is where the 'brace' function of the bridge is most obvious.

Mass:
What Mario said: a heavy bridge is just harder to move, and tends to favor the bass end of things. A light bridge allows more of the high-end sound to 'leak' out of the string and into the top, so, a 'lighter' or 'brighter' tone and less sustain are the usual outcomes.

Saddle height off the top:
I still need to do some experiments on this, but measurements I've been making of strings over the past year or so show that the twice-per-cycle tension change tugging the top of the bridge toward the neck could be one thing that effects tone (let's see, did I get in enough quallifiers?). The 'tension' signal is proportionally greater in steel than nylon strings and greater in strings that are slack relative to their nominal breaking strength than it tight strings. In a plain steel G string the 'tension' signal is only a bit lower in amplitude than the 'transverse', while for a high E string the tension signal is maybe 20% as strong as the transverse. The taller the saddle the more leverage there is for that 'tension' signal to use in driving the top. Note that this is probably only significant at frequencies higher than about the open high E, or for strings that have overtones in that range.

There's a tradeoff here, of course: if you want more of that high-end 'tension' signal it's going to come at the expense of greater static torque on the top, and more bellying in the long run.

So far as I can tell, break angle is not important for the acoustic tone, although it may be an issue with USTs.

I like to angle the saddle back to approximately bisect the break angle, which removes the torque component on the saddle top. This helps keep from breaking out the front of the bridge. some folks say it also makes the guitar sound better: I can't tell.

So, for a cedar top:
Cedar has lower peel strength than spruce, so you want to increase the front-to-back dimension. At the same time, cedar tends to have a more 'bassy' timbre, so you want to keep down the weight, and maybe make the bridge longer. A larger bridge that weighs less is only going to happen if you either make it lower, or use a lighter wood. Too low and you get problems with picks hitting the top, and the shallower saddle slot can be weaker, particularly if you don't angle it back. So I'd contemplate using something like Indian rosewood, or even walnut, instead of ebony.

[QUOTE=Steve Kinnaird] Mattia--I think your bridge is quite handsome, and I for one don't object to longer lengths (wing tip to wing tip). Now the front to aft depth, well, might be a bit much. I'm thinking of your comment about lack of bass, and wondering if this is the guitar whose bracing you pictured a few weeks ago? I thought to myself at the time that the bracing looked a bit stout, and that might be more of the culprit than your bridge.
Just spekyoulaytin' here....

Steve[/QUOTE]

Can't remember which one that was, but this guitar's bracing looks like this, ish (best shot I have):



I do suspect it's overbuilt, though (top a bit thick, bracing could be a touch lower) but not too massively. This thing's LOUD. Very, very loud when strummed, good volume when fingerpicked. I'm also thinking that the biggest brace on the top (the bridge) just *might* have something to do with it

I probably posted a shot of the baritone's top before I shaved the braces by quite a good bit, as I don't have any pictures of the baritone's braces as they ended up online, only pre-carve. I'm guessing you meant this one:



I'd left them thick until I glued the top on because I'd gone a little too thin on the top (I felt), and, well, baritone with heavy strings = lots of tension. I got a better feel for the top 'flex' with it on, and got some pointers from David Berkowitz on what to look/feel for in a baritone (as best is possible over the 'net, anyway).

[QUOTE=Alan Carruth] Mattia:
Your bridge looks a lot like mine, too, except I slope it back from the saddle more, so that the back edge of the bridge is the same thickness as the wings, and round off the top surface a bit more.[/quote]

Sounds like what I was wanting to do with the next incarnation of this one. It's a bit too 'bulky' behind the saddle for my tastes.

[quote]
So, for a cedar top:
Cedar has lower peel strength than spruce, so you want to increase the front-to-back dimension. At the same time, cedar tends to have a more 'bassy' timbre, so you want to keep down the weight, and maybe make the bridge longer. A larger bridge that weighs less is only going to happen if you either make it lower, or use a lighter wood. Too low and you get problems with picks hitting the top, and the shallower saddle slot can be weaker, particularly if you don't angle it back. So I'd contemplate using something like Indian rosewood, or even walnut, instead of ebony. [/QUOTE]

I'll leave the bridge at its 6.75" length, then, which seems plenty 'wide' in that sense. Front to back it's currently at 40mm, which could do with trimming down; it's got a lot of gluing surface, but it would also have a ton of mass!

I'll be installing a (largeish) clear pickguard, and this player's got a pretty light touch with the pick. The 'problem' here is aesthetic; the guitar in question's that pearl'd up jumbo (16.6" lower bout), Walnut/WRC that I posted a few design question about a while back, and it does need a black bridge that'll get a touch of inlay. I suppose I could stain an EIR blank, or even a MadRose blank black, although I'm not sure what to use (Can't get stewmac's fingerboard stain shipped here, and I don't want it to bleed, and there are the pores to consider vis: ebony). I tried talking him out of an ebony bridge, but he was having none of it. Ah well.

I'll make one in ebony, weigh it, and see where it comes in, make a comparison model in EIR (while I'm at it) and compare.

Difficult choice...

Thanks for the food for thought, by the way; always very much appreciated, and filed away for further consideration.

Very Nice looking bridge. I like the arched peg holes. I would like to use that but I use a SM jig for intonnation... I would have to modify it to work with an arch but it might be worth it.

_________________
Joe Beaver
Maker of Sawdust

Hey Mattia, yes that baritone top does indeed look like the one I remember. The first top looks fine to me, though I would scallop the center of the tone bars more.
(Sheesh, I'm sorry--this being a bridge post and all...)

Steve

_________________
From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

[QUOTE=Alan Carruth]So far as I can tell, break angle is not important
for the acoustic tone, although it may be an issue with USTs.
[/QUOTE]

that is interesting Alan that you say this as I've always thought, and seen
quite the opposite. The more severe the break angle, up to a point, has
always seemed to , at least in my experience, made the guitar in question
louder, and a more aggressive tone in general. Not saying your wrong or
even that I'm right, but could you elaborate (in as simple terms as
possible for the ones among us who don't do babblespeak..namely ME) as
to why you say this.

_________________
John Mayes
http://www.mayesluthier.com

I like to take a little liberty with bridges sometimes. I just make them
approximately the same footprint and weight.
2006-02-11_203737_twirlbridg.JPG">KenMcKay38759.8607986111

Let me try this again

KenMcKay38759.8633101852

Hesh: good questions, and ditto.

Update: I've decided on an EIR bridge for this guitar, sticking with the design, and going thinner. I found a very, very, very dark piece of EIR in my small pile of EIR-blanks-that-are-big-enough, almost black/purple with a few slightly lighter streaks, that'll blend in with the overall look nicely. A touch of oil might darken it to quasi-black.

I've got two guitars to make, and as soon as the weather's warmer (I use my drum sander a lot on the briges, which means working in the shop, aka outside) I'll make at least 2, maybe a third in ebony for reference, and weigh the lot.