Official Luthiers Forum!

Hi

Who leaves a gap between the bridge plate and braces ?

Is it better to have a gap or should it be tight fit and what's the thinking behind it

Many thanks

I have always butted the plate against the X. Have not given it much thought till just now. I would doubt that there would be much difference mainly because of the heavy brace (bridge) that over laps plate and X brace. But that is pure speculation on my part, have not found a way to do an instant a/b comparison.
Tom

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A person who has never made a mistake has never made anything!!!

Butt butt butt!

I bevel all the edges of my bridge plates to about 0.75 mm thick, and butt them against the braces.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Butt --- I glue the BP on first and use it as the anchor or positioning point for the rest of the bracing.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Ok thanks...did read on a couple of sites to leave a 1mm gap all round but they didn't give any good reason

Servicability?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Yes that's probably it Colin .. is there a chance of a buzz from a close but not touching do you think?

But.... it was on the Internet so it has to be true.... right....

I bevel and butt and don't inlet for ease of future serviceability.

The serviceability is there if the plate is butted and beveled or a slight gap but I would not do the slight gap.

Inlet plates can also be removed but the language gets more.... colorful...... AND it's very possible when heating a bridge plate and if you use too much heat to split the center seam.... not good.... Inlet plates usually are harder to remove more heat in time duration, etc. making them riskier operations when there is no benefit to inletting the plate.

This is how I do it too. Works great.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Looks as though I'm in the minority. I taper the edges of the bridge plate that run parallel to the X and leave about 1/16" gap. Why? Because the man who taught me did it that way on the 340+ instruments he'd built by that time. Apparently, both methods work.

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michael propsom
www.propsomguitars.com

I tried leaving a slight gap between the bridge plate and the X.... Good way to end up with funny wrinkles and bulges in the top unless you keep your top fairly thick.

The lighter you build - the more you rely upon the matrix formed by the entire bracing scheme to carry it's load.

Great post and I completely agree. OTOH when folks build heavy with thick tops it's less or not at all an issue.

Michael may be referring to Bozo. Bozo's instruments were on the heavy side IME (we've seen them a few times now) and the tops were thicker than what we see the Somogyi crowd and others doing these days. It likely worked very well for Bozo for this reason and would work well for others with thicker tops for the same reasons.

What I like about John's answer here and completely agree with is he refuses to discuss an element of the top out of the context of the "system" of the top - good going, that's my take too.

Definitely butt with beveled edges. From my understanding, butting it up against the braces is for structural reasons because the bridge is torquing


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I can't imagine a 1/16th in gap would telegraph through a thin top and or make for a weaker structure. Seems like such an insignificant and small gap.

I always taper the edges. Butting the plate and the finger braces does make it easier to glue down the X though.

I suppose you could always try it and see for yourself.
3 guitars was enough for me.

To TruckJohn and Hesh's point, this is part of a larger discussion. I want all my bracing connected, but not to the point where tone bars are tucked into X-braces for instance. (Mostly my fear of over-stiffening the top probably) But serious proximity? Yep. And by serious proximity, I mean braces butted right up against one another.

I know there's debate over this, but do braces carry vibrations from the bridge/bridge plate out to the outer reaches of the top? Are they basically "irrigation canals" carrying sound instead of water?

I tend to think so. I may be wrong, but that's my story and I'm sticking to it

So I'm trying to have the best of all worlds. The top is fundamentally tied together, but there's still room for some excursion.

So is 1/16th "proximity"? Not enough, to my way of thinking, but I've been wrong before.

At least once. Maybe twice. Maybe... Okay, never mind

Steve

One way to find out, always... build it and see. My mule that I built and proceeded to try out ten separate tops later in life became my favorite guitar ugly as she is....

JF makes a good point and the gap is pretty minimal. Steve's point about the canals I always referred to as "meridians of vibration" which I believe is the same point!;)

We all have our belief systems and one of mine and apparently Steve and John's too is that guitar tops are basically "systems" and need to be thought of as same. By the way Somogyi teaches this referring to a guitar top and entire body as a monocot which is very much a "system" descriptive word.

Referring to a guitar top and entire body as a monocot is just friggin' weird. The word monocot is short for monocotyledon which is a term of plant anatomy that has no connection whatsoever that I can see to guitar structure as a system. The flowering plants are divided into two broad evolutionary classes based on whether the seed of a particular species has a single embryonic leaf (monocotyledons) or a pair of embryonic leaves (dicotyledons). The monocot species are basically all of the grasses including the cereal crops.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Monocoque, not monocot.

I bevel and butt. Don't see any reason why a gap would be beneficial. Though I don't think it would hurt anything either in the case of small bridge plates, since the bridge stiffens the same area. But with a thin top and large bridge plate, I'd definitely butt it up against the X for stiffness purposes and appearance (the telegraphing that John describes).

Ah, yes. Like and airplane fuselage or a Formula 1 chassis. Makes a lot more sense.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Thanks Dennis for the correction - spell checkers need supervision and when it's this late so apparently do I.... Monocoque was the intended word and concept.