Official Luthiers Forum!

Do any of you have a target weight (or concern) for your bridge+pins?

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Measure Twice,

Karl Borum

I tend to go for about 25 grams for the bridge itself on a steel string, but that's just what works for me. Add a few grams for the saddle, and anywhere from 3-8 for the pins, depending.

Well, yes, but…it is what it is. 38g for ebony and pins and saddle, 25 on the occasional rosewood bridge. That’s for a 1x6 rectangular bridge…

This was a great article:

"Whatever else a steel string guitar might have going for it, a bridge in the mass range
35-60g almost certainly condemns it to acoustical mediocrity. It certainly could not be
called a responsive guitar." (Gore, 161st Meeting, Acoustical Society of America. Session 3aMU: Musical Acoustics. Seattle, Washington. p18 )
https://goreguitars.com.au/wp/wp-conten ... aper-1.pdf

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Measure Twice,

Karl Borum

My target weight for bridges is 25 - 30 gm. I don't weigh my bridge pins, I use Waverly bone unslotted pins exclusively unless a client specifies something else. I will not install any pins that are excessively heavy like brass or other metals - if the customer wants them they can find someone else or do it theirselves.

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Steve Smith
"Music is what feelings sound like"

Wait, so you mean I SHOULD NOT have been using African Blackwood for bridges all this time!?!

(It’s the interrobang that lets you know I’m kidding, right? )


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On guitars with scalloped bracing it seems that a heavier bridge helps.

The 'job' of the bridge is to tell the string how long it is, so that it 'knows' what pitch to make. It does this by providing a fairly large impedance mismatch. Impedance is the measure of how hard it is to move something at a particular frequency; it's proportional to the square root of the mass times the stiffness (including the top at that point). Scalloped bracing has low stiffness in the center of the top, which helps enhance the low end sound by making it easy to move in that range. When it's too easy the energy is drained from the string fast, and turned into sound: the dreaded 'thuddy G'. Adding mass to the bridge helps keep the energy in the string for a while, and also drops the 'top' resonant pitch, which enhances the bass. The cost, as Gore says, is in 'responsiveness'; the ability of the guitar to make a good sound when it's plucked lightly. There is a gain in 'headroom' though.

The bottom line is that the rosewood belly bridges I have seen tend to weigh around 25 grams, and the ebony ones are 5 grams or so heavier. Swapping a light bridge onto a scalloped top can cause problems.

HA! Exactly why I asked..... making my first bridge, and its African Blackwood

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Measure Twice,

Karl Borum

I use Black Locust for bridge plates which is one of the heavier species so that adds a bit to the 'system' weight.

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Steve Smith
"Music is what feelings sound like"

I've been thinking about bridges after seeing how ken parker makes his for his archtop. For those who have not seen it It's 1 piece which is hollowed out to a weight of 24 grams. I have been using AB d.menaloxylon and they are weighing in around 45 gr so I am going to at least round over the tail end to lighten it up but although unlike an archtop it has to be glued down, I wonder about hollowing it out. Sounds dangerous I suppose. But has anyone ever tried it? I have an AB bridge plate that I made and a smaller footprint and at least .015 thinner. Or have people reduced the foot print size?

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Mike McNerney

I believe that the bridge/bridgeplate combination has an additional function which is to couple the string motion to the top such that the whole center region of the top moves when the string moves and thus pumps air. If the combination isn’t stiff enough, a lot of sound can be lost in local vibrations that don’t move the whole plate. We’ve all heard some very quiet guitars where it’s clear that the center of the top isn’t stiff enough. So adjusting the mass of the bridge can adjust the tonal response, but the stiffness of the bridge/bridgeplate combination is also important. It always seems to me that Rosewood is stiffer than Ebony of the same dimensions. I also control this stiffness with the thickness of the bridgeplate.

Usually 20-30g for the bridge itself, even if it is African blackwood. Only the wall in front of the saddle needs to be full height. Taper the blank from the underside after routing the saddle slot and drilling the pin holes, so they're tilted back a few degrees. Then carve more taper from the outside while shaping the wings. This one is 30g. 7" long, S-shaped for fan frets.

So nice to see some view the bridge as part of the "system" that is going to do the bridge's function.

When building I shot for 25g to 32g also like my friend Steve but in hindsight I see this goal as much less important. Instead every guitar is different and I suppose that when you are a factory you can build to a spec and get decent results 95% of the time. But for excellent results the stiffness of the top, bracing, system, the action of the instrument (yes the torque from saddle height) string gauge and player attack. Even the sort of music played is also a consideration for ultimately what bridge weight IN COMBINATION with the rest of the system would be optimal for that one, specific instrument.

I'll add as players when a top system is too stiff we can dig in or conversely when it's too floppy we can ease off. This makes us part of that system.

There is also the issue of your goal here. Is the goal the most volume possible or maybe warm tone with lots of over tones?

With all this said Lutherie for me is an exercise in the more I learn and know the less sure of myself I am about any of this stuff. I now see optimal bridge weight as a function of so many other things that's it's really a crap shoot. Maybe there is a reason why the words Lutherie and luck both start with the same letter.

I have been using "B" grade African blackwood for quite a few years. It may not be quite as dense as the better stuff (haven't measured it) but I like the results I get and it brought the cost of a bridge blank down to about 50 cents (when the cost of ebony was about $3 IIRC)

Adding a point of discussion/ interest, I am reading Giuliano Nicoletti's 2023 book Mastering the Sound of the Acoustic Guitar. In it, he gives a general bridge weight recommendation (matching what many of you guys said) of "not to exceed 20-25 grams....while the bridge plate should weight around 4-8 grams".

The book's focus leans towards large body steel string guitars, and, in general, notes if otherwise. The bridge design recommendation does not specify playing style. He is also clear in noting that attention, prior experience and experimentation are always key design elements. This has been a very good book for me to gain a rudimentary understanding of the design and acoustic fundamentals effected by even small design choices (it's also helping me to graduate to Trevor Gore's books). Some of you are listed in the bibliography.

Feeling really grateful to be able to participate in this group- thank you all.

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Measure Twice,

Karl Borum

I've made a few with it including pyramid style and archtop bridges. Man, it's a bear to carve!! Thank goodness for abrasives.

My African Blackwood bridge weighs in at 45 grams, with undersized, unchamfered string pegs holes and a 1/8" saddle slot. Given the target; "...range from 20 to 35 grams" (Gore, 161st Meeting, Acoustical Society of America. Session 3aMU: Musical Acoustics. Seattle, Washington) I dont believe there is any chance of reducing the weight by 25%. Calling for suggestions on an aesthetically-similar-to-African-Blackwood, but lighter bridge material..... Dark rosewood comes to mind, as the finger board does have brown streaks.

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Measure Twice,

Karl Borum

It’s not too hard to get an ebony bridge to come in around 30 grams.
But I’d use a darker rosewood and put some oil on it myself.

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Jim Watts
http://jameswattsguitars.com

Is the bridge a traditional shape that has very specific dimensions you can't deviate from? Here's another one of mine, where I made it to 24 grams. 6" wide, 3/8" tall at the front, wings about 1/8" thick or a bit less.



As for alternatives, Brazilian rosewood and bois de rose are both near-black if oiled or shellacked, but very scarce so I'd recommend saving them for later. Same with bog oak.

Dark Indian rosewood is probably your best bet.

Stained walnut is also an option, and about half the density of ABW.

Thanks beautiful, Dennis!


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Stunning bridge designs Dennis. Yeah my braces, bridge plate and both clamping cauls, one clears the braces, are based on a Martin shape bridge. But I do get your point!

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Measure Twice,

Karl Borum

So there are other important considerations to why bridges, successful designs are as they are.

In around 2008 I started a thread here titled "Why Are Bridges Designed As They Are" and that thread devolved into perhaps the biggest fight the OLF has ever had. Can't take me anywhere.

So not only is a bridge a brace, a very important brace, an anchor for the strings, a hopefully transparent pass-through for vibrational energy, a hand rest and for some of you another pretty face it's an important component that should be able to be removed with NO damage to the bridge or the top.

A bridge has to be serviceable. I don't know what the percentage of guitars that have had lifting bridges is but it's paid off my mortgage so I know it's substantial...

With this said Gibson is hated in the industry for a number of reasons and one of them is some, not all of their bridge designs. When viewing a bridge shape consider that the finish of the guitar has to be scored to install the bridge. Also consider that someone like me is going to put a 250 watt heat lamp very nearly in contact with the thing and I do at times touch the bridge as well with the lamp. Bridges have to be designed with the idea that they may lift and need to be completely removed without damage to the instrument and then reinstalled hopefully in a manner that no one can even tell that the bridge was ever off.

One of my Heshtones was left in a black car in Nashville for a week and the HHG let loose and the back edge of the bridge lifted. It was a piece of cake to get off and reinstall with no damage to the top and the repair is invisible. That was ten years ago and it played out Saturday night in this area.

Remember too a lot of inlay on a bridge is called two words in the repair trade, scope creep. If it creates the possibility that the inlays will come loose with heat it's not serviceable. Sure we can carefully remove the inlays like we do on fret boards and then reinstall them later but I'm going to charge you for this as it takes more time AND care.

The goal of any good bridge design should always include serviceability.

lol, that sounds like an entertaining read, but I can't seem to find it. I found this one, but you didn't start it, and it's more of a polite discussion than an argument https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=19905


Yeah, I try to stick with only carving, but sometimes the artistic vision is good enough to be worth it.

The bird wing bridge has been removed and reglued once already due to a measuring error the first time... thankfully glued before soundboard finish, and I noticed the problem before drilling the holes through the top, so it wasn't too much trouble. It's a better example to copy from in general, but the butterfly shows how far you can go with weight reduction if you really want to.

Dennis, the PermaBond 825 I mentioned in another thread might be good for that type of inlay. Melting point of 200*C, well above what you need to remove a bridge…

My dear friend Hesh! After I tead your post yesterday evening, I went to bed. In the night I woke up laughing out loud! Why? I had a dream: Hesh is visiting the Museum of Modern Art. He is looking at these beautiful pieces of art and comments them " How nice, very impressive, wonderful colors, makes me feel.....BUT THE SERVICABILITY! TS TS TS....!

I understand your thoughts as a repair man, and you know that I have the greatest respect for you, your awesome knowledge and work, but there are other points of view. I have seen many very beautiful guitars here in the OLF, and I think they are expressions of the hearts and souls of the builders. I am not a factory builder who earns money with his work. I am a hobby builder who loves guitars, I love and respect the wood I have the pleasure to build with, I love and respect the craftmanship we all need for guitarbuilding, and I love to let my thoughts become reality in wood!

I don`t think that the famous luthiers like Antonio de Torres, Hermann Hauser I., Conde Hermanos or even C.F. Martin I. have wasted one thought about serviceability!

We all spend hours and hours and hours in thinking about the design and how to achieve the result we are hoping for, building our guitars and hoping at least to hear the sound we hear in our head coming out of the guitar. We give our mind, heart and soul into this piece of art (and that it is for me!).

When you are lucky you find a customer who likes your piece of art and spends his money for it.
But if this customer is so disrespectful to your work and leaves it in a hot car for one week, he has to pay the bill for his disrespect and stupidity!

Again, I respect you and your repair work, but it is not my goal to make you your work as easy as I can. My goal is to build a guitar as good as I can which is an expression of mine.