Official Luthiers Forum!

It could be the number of repairman with a full set of building skills and vice-versa is staying the same, but simply being dwarfed by the vast quantities of hobbyist builders and barely trained "guitar techs" (such as are popping up in GC's across the country all of a sudden) that have no building skills and hardly any repair skills.
We live in the information age, where if you have an internet connection, you're a luthier or a guitar tech, seemingly overnight!
I mean no disrespect to anyone on this forum, most of the gentleman that frequent this forum are very genuine about their respective skills.

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Old growth, shmold growth!

That may be. It does seem like there are more "wanna-be's" in the mix since the internet allowed anyone to post videos and tutorials without benefit of review by experienced peers. As I remember when ASIA was formed, that was one of our stated goals - to provide a method of certification for apprentices and journeymen in the field of luthiery.

When I closed my shop in 1990, and let my membership in ASIA lapse, I must admit I willingly remained separate from the scene, and only in the last year have I dipped my toe back into the community of luthiers.

I'm sure I've missed a lot in that time - whether for good, or for bad. Thankfully, I still have all my tools and enough clients and family to keep me busy when I wish to be.

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"Act your age, not your shoe size" - Prince

My thoughts are why bother pretending to make a radiused top if you are going to glue a flat bridge on top? Like Todd stated, the bridge will be the strongest brace on the guitar so if you had a nice radiused top before glueing a flat bridge, the crown of that radiused top is now likely flattened by the bridge. In other words, I don't see how the bridge would be forced to take the radiused shape of the top......instead the top will take the shape of the bottom of the bridge. So again, why bother radiusing if you are going to flatten the radius out?

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Formerly known as Adaboy.......

Just a Tony who is arrogant..... sure you wouldn't like him.

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"Act your age, not your shoe size" - Prince

However counter-intuitive, this is simply incorrect. Two obvious truisms come to mind: first when you use a shallow radius (over 40') your top is almost flat and a flat bottom bridge can be pressed into place with finger pressure with no gaps. Second the radius will change slightly depending on RH, the mood of the top/brace system and so on, so the chances of it being exactly 40' (or 60' or whatever your dish is) are about null.
Lastly, gluing a flat bottomed bridge can alleviate some of the excessive bellying that can happen with shallow radiused tops. As the glue shrinks, and later with string tension the bridge (and the top with it in that area) will naturally lift into a more domed shape. This is a known technique and I know quite a few successful builders doing this. I've never seen a curved bottom Martin bridge (although I do not know what they're doing now).

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

I guess I am in the minority here because I never radius the bottom of my bridges and I have yet to ever have one come flying off, no bridge/top distortions and or cracks or anything. Having said that, I had a classical guitar in for a repair that had a pronounced radius a few weeks back. It took me 5 minutes with a scraper to fit it perfectly. So it has nothing to do with wood working skill or time or anything like that, when I fit a bridge to one of my tops there is no noticeable gap present, so whats to radius?

I've removed PLENTY of old MArtin and Gibson bridges that have had the bottoms curved. However, I believe that the bottoms of the bridges curved AFTER being glued, as the top distorted over time, wood being the elastic material that it is.
It seems to me that the bridge will only conform just so much before popping off.

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Old growth, shmold growth!

It's not about that, Todd. WE don't get to choose where our instruments are taken by the owners. Yes, we can wish our client wouldn't go to so-and-so's shop, but it's their choice.

Years ago Roger Sadowsky wrote an editorial about the same thing, and said about his clients "They are gonna go to the other shops. Count on it! Get used to it!".

Sure, there are guys in town I'd rather not see my work visit - but WE don't get to choose. That's all I'm saying. (hijack over)

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"Act your age, not your shoe size" - Prince

I'm a know-almost nothing hobbyist, but I try to shape all parts of my guitars (and related gluing cauls) to match one another. Not because I think I fully understand the physics of how a guitar works, but because minimizing the amount of stress one introduces during construction seems like a generally good idea to me.

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George :-)

Then there is the philosophy of building under tension, of which using using a radius dish (or form) is part of. No plate conforms naturally to a given radius, or curve, and one has to force it with respectively shaped braces.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

There are a lot of variables and combinations that come in to play here as to radius the bridge or not, adhesives used, clamping techniques, etc. Here is what I learned from the school of hard knocks. You will probably get by just fine radius or no radius on the bridge either using Titebond or HHG ..........if you use clamps..........My problem arose when I switched to vacuum. Sanding the bridge to the theoretical radius (radius dish/bracing radius) is not close enough for vacuum clamping. Just some personal observations. Hope this helps.
Rod

Then there's the Hauser example of building flat and inducing a dome with a domed bridge.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Thanks for that feedback Laurent. A queston so hopefully I can get this clear in my mind. Are you considering the long term shape of the top/bridge over time under string tension? (where my comments are more looking at the immediate affect and shape of the top/bridge) For anyone else reading this, please don't think I (a novice) am questioning Laurent, instead I'm questioning trying to clear this up in my own mind. I think you are saying there may be long term reasons for using a flat bridge on a radiused top. Would this differ significanty from using a flat bridge on a non-radiused top?

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Formerly known as Adaboy.......

Also in the case of many classicals, the dome of the top is established by pressing ‘flat’ fan struts into the top such that the top and fans conform to the solera dish. The glue joints along the fan struts hold the dome shape in the top.

If the bridge is not shaped to match the dome exactly, some distortion of the dome will occur when the bridge is glued. (This may or may not be desirable, depending on the intent of the luthier.) Also, if the internal clamping caul does not match the desired dome, uncontrolled clamping distortion could occur when the bridge is glued on.

Joe

Darryl, I am not sure I understand your question(s). If you re-read my posts on this thread you'll see that I infer a radius over 40' is very close to flat, and gluing a flat bridge on it does no harm, and will induce a bit of tension (really not much) that could be an advantage to the whole structure. BTW the same method applies to the rim: gluing a top with a 40' or over radius on a flat rim will induce very little tension. The top side of the rim is obviously flat on a lot of vintage guitars.
For tighter radiuses (say 25' and under) it is a different story, and shaping the bottom of the bridge to match the top's is best (as well as shaping the rim on the dish).
I don't know how to make my thoughts clearer…

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

I suspect this is a real X-brace vs fan brace issue - you probably can't alter the dome of the top much with the bridge once the X has defined it, whereas fan braces don't fight the influence of an arched bridge hardly at all. I suspect these are two different worlds.

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Jim Kirby
kirby@udel.edu

Not necessarily. Tops (or backs) can be arched using humidity very successfully, and that is a very traditional approach. There is an amazing thread in the UMGF called "Flat tops vs Arch bracing" which goes into this subject in tremendous detail.



Right. So this is really the heart of the flat vs arched bridge debate. Either you want that kind of tension, or you do not. Or perhaps somewhere in between. Different styles of construction for different styles of instruments.