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Ed, the most illuminating discussion that I've seen on pinned verses non-pinned bridges is here.

Once you've read through the 8 pages of discussion, I'd appreciate your thoughts.

(Definitely worth the read, BTW, although is does get pretty technical).

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I can tell you for a fact YES. on a pinned bridge the pins to pull on the top and the plate carries the main load off the strings the resultant torque and tension are shared with the top. On a pinless all the stress is placed on the top via the glue joint. The larger the glue area the more the joint shared the stress. The design of the bridge will determine the footprint thus the stress per sq in is a variable.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

That seems logical John. However if a pinless bridge is bolted the bolts will pull the bridge/soundboard/bridgplate together lessening the stress on the glue joint, yes? So if one were to bolt the pinless bridge wouldn't it carry the main load better than a pinned bridge? I am no math whiz so I have no idea if it is correct but in just thinking about it the pinned bridge is not compressing the bridge/soundboard/bridgeplate together where the bolts actually would make them act as one piece and help the glue joints by not allowing as much shearing.

So it seems on the pinnles bridge, as the strings try to pull the bridge forward, the bolts would actually pull the joint tighter so the sheer load would be transfered to a torque doing much the same as a pinned bridge except a pinned bridge doesn't pull the bridge/soundboard/bridgplate together.

I am not sure but I am just thinking through the physics (not in a math way) of how each system works.

Maybe someone that understands the math of it all can explain it better than I can (or show me where I am mistaken)

Just thinking out loud here...

Bob

no. A mechanical fastener is like a clamp. The bolts will only secure the points of direct contact. The variable is the stiffness of the bridge and top. The glue joint is still the connector and what is the weakest link, is if you are bolted without a plate , the bolt will only be as secure as the weakest point of contact. That is why on a failed joint a bolt will often be pulled right through the top.
The bolt cannot pull the joint tighter unless you tighten the bolt. As the wood shrinks there can be play in the bolt and it then becomes useless in the joint unless it is retightened. Also as a side note , if the bridge expands ,the head of the bolt or the nut/washer will pull against the wood. The weakest wood will compress over time and again , the bolt integrity can be compromised as a support for the joint and then the glue is carrying the full load of the joint.
Gibson bolted on a lot of bridges that over time still got loose. A good joint is often stronger than a mechanical fastener.

think of it this way
a bolt connection surface area is the bolt . head ., or a washer. So the footprint is the only true secure point of contact. Glue on the other hand can have a good surface contact area that far exceeds the bolts footprint. The only thing the bolt will do is catch on it when it is tight.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Maybe I am wrong but a bolt and washer does secure more than just the contact points. I know we are getting into the realm of engineering which I do not have a degree in but I do have one in Industrial Design so I have a half way decent knowledge of fasteners. It is my understanding that any fastener will use the surrounding material and spread the load in a radius around that specific fastener. That is why when designing a product you would space the fasteners specific distance from each other depending on the material (that is where I would use an engineer to figure out the spacing).

And also in a situation where you have a bolt and sheer forces the bolt actually acts as a pivot to compress the materials it is holding together toward each other. Of course you are correct when saying the bolts will pull through the weakest point and end up failing but a lot of energy is needed to get to that point.

I guess what I am saying in all of this is if I were to use a pinless bridge I would glue it as well as bolt it. My reasons are twofold, 1. The bolts would act as a guide to position the bridge in the exact location I needed it. 2. They would give an added measure of fastening to help avoid the sheer forces of a pinless bridge. I would think the glue and bolts would work together to hold the bridge securely.

I know that is how Gibson has done it for a very long time (including pinned bridges) and I don't think there is a failure rate higher than any other manufacture by using bolts.

Bob

A bolt ,the size that is used on a guitar bridge is only as strong as the weakest point. I was a machinist and tool maker and a mech ind degree. The bolt will help to a degree but in fact , the bolt shouldn't do anything on a glued joint. The glue is the connection , if the glue fails the bolt will only be as strong as the weakest point.
Think of it this way . the top flexes as will the bridge. The top wood will compress pretty quickly.

Sorry but that is the way they work. The shear on the bolt with give way to the weakest structure ( the top )

I agree it will pin it while gluing.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I'd be curious to hear from some of the more repair oriented people.

Do Pinless bridges have a statistically higher fail rate than pinned bridges?

This strikes me as something that enough people have talked about enough times that there should be some sort of consensus conclusion as opposed to opinions and theories...

Trevor,

8 pages eh?

Well, I guess it's good that the apprentice has been whisked away to Hawaii to give bass lessons so he can't see me not working while he's gone...

I do do this for a living. While pinned bridges are a lot more common . when the pinless bridge fails it is more pronounced. The bridge seldom pops off. Classical's are also pinless . I say that of the pinless bridges that I have seen fail , there were no plates and the braces didn't go beyond the front corner of the bridge.
I also have to wonder if this is because of outside issues , as if the guitar is left in a hot car etc.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Numbers wise I don't get anymore pinless bridges in for repair than pinned but considering the number of the two types out there that is most peobably a higher % of pinless than pinned.

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"I've been had again"
Tim Benware
Creedmoor, NC

I have built 3 Harp Guitars with this bridge. The most recent one holds 21 strings. There is a combination of an X brace and fan bracing beneath it plus a maple bridge plate. I used a closley fitted caul taped on the inside when I glued the bridge in place. I hope I never have a problem in the future but if I do this will make a beautiful wall hanging in a resturant some where.



Michael

And that would be the statistical data that would interest me. Are there for sure a higher percentage of Pinless bridge failures than pinned? Classical don't count!

Let's hear from some more repair oriented folks...

I've worked on over ten thousand guitars, blah blah, you've heard it before.

I've seen my fair share of both bridges failing.

When the pinless bridges fail, it's often pretty catostrophic.

The pinned ones are almost always extremely repairable.

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Old growth, shmold growth!

Playing the devils advocate here....

I have repaired a number of pinned bridges that have failed and most of those have been because the bridge has cracked along the pin holes. When that happens it usually cracks the bridge plate with it. Actually I think it is the bridge plate that cracks first and causes the bridge to crack. Either way they required that the bridge plate be replaced along with the bridge.

I have only repaired 3 or 4 guitars with pinless bridges one of which did pull the bolts through the top. The others were just starting to lift and had not failed.

If a pinless bridge didn't have bolts (which I have never repaired) then it seems it would just shear off from the top and not effect the bridge plate or require extensive work to replace.

I can say as a new builder I don't plan on experimenting with a pinless bridge to see how they hold up. I think there is a reason why a pinned bridge is used on most guitars so I plan on sticking with the norm. I also think that it is driven by the customer, pinned bridges look like a "normal" guitar where pinless look different so are less desirable.

Bob

John's correct and great example using a classical bridge as well - they are indeed pin less too.

On pinless bridges that have also had bolts the bridges lift anyway and all the bolts seem to do is prevent the bridge from visiting the nut.... but often at the expense of the bridge plate too. Or, in other words, bolted pin less bridges seem to do more internal damage when they lift and they still lift just like pinned bridges.

Like Ben we see failures in either and often too. As such I also would not estimate one to be more secure and longer lasting than the other. And like Chuck our Blah, blah, blah.... affords us a view of far more lifting bridges than most folks ever will see.

Here are some pics of an interesting repair. This is what happens when a 82 year old personal friend of mine receives bad advice to put steel strings on an old Guild classical....

You can see that when this bridge gave it decided to roll up the top like a sardine can opens.... Extensive damage, lots of runout in the worst place on this top too, and one heartbroken Vet who asked his friend to help AND who frequents the children's hospital with this guitar playing and singing for sick kids. Dave and I were able to repair this nice old ax so that it looks and sounds just as bad.... as it did before the mishap and my friend was made whole again and lots of sick kids are again getting entertained as well. This is also an example of why, personally, I now do what I do and love it!!!

Bolts may initially add some attachment value but over time wood compresses and the fasteners lose their tightness, the glue layer may deteriorate just like a pinned bridge and for the same reasons, the fasteners become important again until the wood compresses even more, and the whole thing needs to come off anyway and be repaired correctly - just like a pinned bridge.

And then there is also that added mass that bolts add..... right in the very worst place to add mass as well, the center of an acoustic guitar top.

Hesh I also have a friend that has put steel strings on a classical. When I asked him why he would do that. He explained"For the sound of course".
I have no idea how he thinks a classical guitar with steel strings on it sounds better then the nylon strings it was designed to use. Now the guitar is a newer Martin made out of MDF I suppose. I just cringe when I see steel strings on a classical guitar. You know as well as I do that it happens a lot. I didn't notice whether or not his bridge was lifting but it's probably just a matter of time. My 02 cents


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Hi ya Lonnie! Yeah we see this, steel strings on classicals, a lot and it always worries me too.

One suggestion for your friend that you may wish to make is to suggest Martin's "Silk and Steel" strings instead of just steel strings. The Silk and Steel will likely make your friend happy because they are not classical strings but they are lower tension than steel strings also likely keeping the guitar happy too.

I used to do a bridge patch for classical guitars but have since stopped doing it. I once built a classical guitar for a guy who uses piano wire guage strings on his acoustic guitar, which I also 'over' built for him. I made him promise me he would not put steel strings on it and so he did. Years later I saw him playing it with steel strings

The bridge as far as I know is still on.

I've done too many bridge reglue's to remember but it's not fair to compare a lot of them. Like Ovations for example. One would be lead to conclude that a pinless design is awful if you have ever worked on Ovations but then when you glue a bridge right to the finish what do you expect. When I reglue those I just leave the bolts off as they tend to just cause more damage.

Hi Hesh I was happy to see you on this forum when I joined. I know that if I need to know something your the guy to ask. As far as my friend and his classical guitar with steel strings. Have you ever met someone that you couldn't tell anything too? We'll meet my friend. He will just have to learn on his own. But guess who he'll bring his guitar to if the bridge comes up? I've found that sometimes you just have to let sleeping dogs lie. He was actually proud of the fact that he was smart enough to put steel strings on a classical. There's no arguing with logic like that.


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Sheesh Lonnie my friend I have never met any of "those" sorts of folks.....

Maybe just leave a box of silk and steel laying around when you see your friend and let the idea be their's? Be careful though of letting others have the idea it can also backfire.

I have a life long friend who was concerned many years ago that his first wife was too dependent on him for everything.... He wanted to help the independent side of her develop... so he consulted a marriage councilor and was given a book titled "Why Do I Think That I'm Nothing Without A Man" to give to his wife. My friend complained to the councilor that if he gave THAT book to his wife she would get all upset.

So the councilor suggested that he simply bring the book home and leave it on the coffee table with no introduction or explanation. He agreed to do so and being the sort who likes to follow-up on his thinking he decided to leave a hair under one corner of the book so that he could tell if his wife looked at the book.

The next day the hair was still there, the second day the book had been moved, the hair was gone but the book was back on the table and the third day his wife left him and sought and obtained a divorce.... True story!

The moral or moron depending on one's perspective of the story might be that this is a great book for getting rid of someone that you wish to get rid of.... And heck all the while they thought that it was their idea too!

He took the nylon off in favor of the steel strings. So I think I'll keep my strings and just hide when I see him pulling in the driveway guitar in hand. Lol


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Very informative, so what caliber IS best to use to shoot cedar?

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Kurt Thomas

"There's a first time for everything even if you do it by mistake."

Well, we have these stupid gun laws up here in Canada so I had to use a bb gun. Which suits me just fine, though I'm sure a 12 gauge would have been more satisfying.

Ed, did you get through the 8 pages??

Would be interested in what you made of it.

_________________
Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I'm about 4 pages in. So far, the gist is that yes, Pinless puts more pressure on the glue line, but nobody can really clearly explain precisely why or by how much. 4 pages to go....

I read through these 8 pages the other night and now that the Exedrin migraine meds have fully saved me I would like to offer a couple points. After spending 25 years in the film business, and I mean the "real" film business, where mineral emulsions are very precisely exposed to light and brought to visual realization by precisely controlled chemistry with the knowledge of highly skilled craftsmen, darn smart folks I worked side by side with, I find lutherie a bit self aggrandizing. Although I admire many luthiers for their efforts and study, it is abundantly too rare that any one is furthering the craft in a way that I am accustomed to. In my short 4 years experience, and lay me to rest if it makes you feel better, of guitar building there is a domination of ego, hyperbola, and marketing that I simply don't understand or respect. The 8 pages I read exemplify this, the topic of the thread is rarely discussed, yet forgone opinions dominate, the segues to opine conclude nearly every odd sentence. Little was said that was meaningful, little was offered as a direction, technique or notion. There was certainly an abundance of self serving opinion and the endless endlessness. Please just sell me religion. I would like some focus on making a better sounding guitar, I've made one with a pinless bridge and 20 otherwise, I've had failures as everyone who is honest does. What guitar do you really want to make?

Tim