Bridge plate question...

[Ranny88]

Hey everyone, my name is Ryan and I am new to the forums. I have been slowly working on another dreadnaught and I had a thought. What does everyone think about running the bridge plate under the x braces? I feel that like if you get the laps nice and tight the glue would hold the brace fine in that area. Do you think it would help or hinder sound transfer to the top? Thanks everyone

[mirwa]

IMO, you need to assess the reasons behind each part.

The purpose of a bridge plate is to stop string ball end damage to the soundboard. It is there for no other reason.

X brace is there to provide strength to an area of thinned wood that is subjected to rotational forces from the bridge.

Why remove strength from a part that is critical to the top to add strength to an area that does not require it?

The end point in your proposed situation I believe would be added stiffness to the top which would reduce sound and response and also weeken the main support structure as you would be notching out long grain where it is most critical

Steve

[Ranny88]

Thanks for your quick response Steve. This makes sense I will just proceed as normal.

[redir]

I don't think it would make much of a difference at all frankly. The very good reason for not letting the bridge plate into the x-brace is for repair purposes. So it's a lot more work to let the plate in for very little if at all perceived value and in addition to that it will make some future repair person's life miserable. So why bother?

[Halcyon/Tinker]

I'm not at all sure that the bridge plate's only purpose is stopping the ball ends. If that were true, it would only need to be big enough to cover the area where the ball ends touch, yet it is much larger than that.

FWIW, as I understand t, bridge plates were tucked in the early days, til they figured out what a PITA it was to repair, so they stopped doing it.

You're thinking of undoing an improvement.

[Bruce Sexauer]

I think of the bridge plate as in part a clamping caul. In that role it wants to be no smaller than the bridge itself, but needs be no bigger either.

Tucking is a hedge against glue failure on stressed braces IMO. The BP is not a stressed brace.

[mirwa]

Originally Posted by Halcyon/Tinker

I'm not at all sure that the bridge plate's only purpose is stopping the ball ends. If that were true, it would only need to be big enough to cover the area where the ball ends touch, yet it is much larger than that.

On that theory then, top load / pinless bridges should have bridge plates fitted, yet they do not have a bridge plate, there are literally tens of thousands if not hundreds of thousands of these guitars mass produced by manufacturers that are out there, with no bridge plate.

Whilst I agree that some manufacturers and builders may make the bridge plate bigger and butt them up to the X brace, I really see no point for adding that additional added stiffness to a top.

Steve

[Halcyon/Tinker]

Well, my only experience with pinless bridges is Lowdens, which most certainly have bridge plates.

Can you specify a company using pinless bridges but no bridge plates for me to read up on?

[mirwa]

Originally Posted by Halcyon/Tinker

Well, my only experience with pinless bridges is Lowdens, which most certainly have bridge plates.
Can you specify a company using pinless bridges but no bridge plates for me to read up on?

We all see different repairs.

Top of my head, brand name wise, I see epiphone pinless acoustics all the time without bridge plates.

Steve

[Halcyon/Tinker]

Interesting. It makes sense that an epiphone might be sturdy enough not to need one

I know that I use bridge plates to distribute stress over a greater area of the top which helps prevent bridge roll/bulge, but I can only speak for myself.

[mirwa]

Bridge rolling and stress is a whole another topic, lots of physics actually involved which people rehash and throw about in threads all the time without truly understanding.

The rotational force on a top is created by the difference between the centre of the momment in relation to the centre of gravity within the bridge itself whilst under string tension.

The ability of a top to withstand that rotational force is what I believe you are referring to, x bracing, plate thickness, subsequent tying of the plate into the x brace, all these things can be done to oppose the effects of said rotational force.

Two bridges of the same size and mass, with different momments fitted to the same guitar can alter the top deflection dramatically, that is why a well designed bridge (mathematically) can do wonders to a guitar.


Steve