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I'd like to install a trapeze tailpiece. Question: Do you recommend reinforcing the spruce top with additional bracing? Any input greatly appreciated.

More info needed.... Which guitar, and which tailpiece?

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

I'm not a luthier. I just wanted a project. I got a cheap ($10) Spectrum AIL36 (36") guitar and I'd like to install a cheap, short (4") no-name MIJ trapeze tailpiece because I wanted something a bit different. I've also made a (don't laugh) four string nut and adapted the bridge to accommodate four strings. I plan to play it as a tenor guitar with wider string spacing. Again, I wanted the short trapeze tailpiece just to be different and because it looks cool. Just wondering if I should install extra bracing to handle the string tension.

If you're going from 6 to 4 strings, you're reducing the string tension.

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

Well, it is your guitar. Loss of string tension will change how the top projects (lower volume, say)

Anyways, center tailpiece, pre-drill holes for screws and screw it on. Test your drill bit hole on a piece of scrap to see how screw bites.

Then, you are going to need a floating bridge and place it in the correct location. Do you have a floating bridge? Did you remove old bridge? Were you intending to use the current bridge and saddle? If so did you verify that the strings will clear the back of the bridge?

Hope you did not spend too much on this guitar.

Mike

https://images.reverb.com/image/upload/ ... igur4w.jpg
You spent $10, so I would say you are in the budget.
Just put it on and see what happens. I don't see how it could hurt anything to try it, using the original bridge, and then adjust your thinking, after you see how much the top sinks with the downward pressure.
Worse case, you are out $10. Best case, it might sound like an L-5.

Good point. A typical steel string has up and forward torque on the top. This is going to compress the flat top. No dome. I think it’s gonna not work out well. At worse, strings gonna be too close to frets.

Well, thank you for all the great input! My original concern was that extra bracing might be needed to prevent the string tension from placing too much stress/pressure on the top/end of the guitar. I never considered having to replace the bridge. My thought was that the bridge was installed in the correct position originally so why would a floating bridge be necessary? I figured that all I had to do was ensure that the strings cleared the saddle (they do). Also, I hadn't considered deflection of the top due to the trapeze bridge causing extra pressure on the bridge/saddle. Maybe I was wrong but I didn't think there would be increased downward pressure due to the trapeze bridge. Again, I'm not a luthier. I'm now thinking that, considering all the issues you guys have raised, I would be well advised to install extra bracing to mitigate any linear or downward pressure the strings might place on the instrument. Thanks again for all your help!

If you install more bracing you will almost certainly make the guitar quieter.

Why not try the cheap test first.

1. Lay a straight edge across the body at the back of the bridge and measure how high it is above the sides. There is probably a slight dome, or it might be flat. Your measurement will probably be between 0 and 1/4 inches.

2. Screw on the tailpiece and string up to pitch. Now make two measurements:

3. Distance between top of 12th fret and the bottom of the strings. Something like 7/64 at the low E, 5/64 at the high E would be playable. If the strings are too low so the guitar is unplayable then:

4. Raise the saddle. Easiest by cutting a strip of wood veneer, or plastic from an old credit card, and putting it under the saddle. Get it to a place where the guitar plays.

5. Now make the second measurement, repeating the straight edge across the body behind the bridge. It will have sunk a little, but my guess is not much. If I'm right, just buy a new saddle and sand it down to the height you need, then play the thing.

6. If it sinks a lot, so there is a distinct dip in the top, then consider adding extra bracing, But I don't think you'll need it.

Another consideration is string break angle over the bridge. A flattop does not have a high enough bridge to make sufficient angle to keep the strings in place. The strings may slide around on the saddle and not stay in place. An archtop has a lot of height, plus the bridge adds even more.

May I ask why you want to do this?