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Does this mean domestic guitars should be measured with long grain rice and asian ones with sushi rice (arborio)? What about Mexican and Spanish guitars - Spanish rice?

ScooberJake: In all of what is left of seriousness, the curve fit wouldn't be that hard to manage (famous last words). Wait a minute, I think I like the rice & beans best for the Spanish.

How about placing the guitar into a rectangular box, then fill the area that the guitar isn't in with rice or beans to the level of the top. Calculate the volume of the box, and subtract the volume of rice or beans to get your measurement. You can then subtract for the volume of sides, back, top and braces. Just trying to think outside the box.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I should have said to put the body of the guitar in the box. Cut-out one end so that the heel and neck are outside the box.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

It's actually not a bad idea if you put the guitar in a good plastic bag first. Certainly a very fast way to do it. AND, assuming the water pressure would not collapse the body. I would fill a CLEAN trash can with water, with a hose poking in at the side, right at the top of the water line, lead that hose to a big bucket. Add water to trash can and wait till it stops pouring out. Empty the bucket. Put plastic covered guitar into water, wait for water to stop leaving the trash can. What is now in your bucket is your volume. one fluid ounce = 1.8 in^3

That's not gonna work so well. A circle has the most area for any circumference. A guitar outline and a circle might have the same circumference but the circle will have more area enclosed....and then more volume when you figure the height. Then you're missing the volume of the back taper, blocks, bracing which would add up.
Other methods:
Easy way...Draw it on graph paper, including the blocks, and count the squares enclosed. Multiply by the body depth at the neck. Add in extra for the back taper....probably about 1/2 the area X the taper amout

Really easy way... Draw it on a sheet of cardboard. Maybe 20" x 30" or 600sq in. Weigh the cardboard to get grams/sq in. Cut out the shape and weigh the shape again. Figure the sq in from the weight. Do the rest as above.

If you are getting computer tech, I have seen at trade shows CAD systems that included a lazer that you could use to scan an object and then the data went into the computer and was converted to to a program that could recreate the object.

By the way, I do not know, but is the VOLUME really a governing parameter, or is the volume just an approximate function of other more important parameters, e.g., the length of certain dimensions and the ratios of the lengths in different directions?

I can just hear two guys bragging about their guitars. "Well, mine is not the loudest one at the jam, but it holds 40 lbs of rice." "That's nothing, mine holds 43 lbs."

The volume will be a governing parameter for the frequency of the cavity modes.

I will say that the idea of using rice to clean out a guitar is interesting. May give that a shot.

I dunno. I tried the rice cleaning trick once and had the same experience as Arnt. It took forever to get all the grains out of the kerfed linings. Moving up to a larger grain like corn or something should avoid this problem.

This is what is great about forums and other people's experience. Ok, rice out, corn in.

Mike

Ps: then again, perhaps an argument for reversed kerfed lining?

Dunking in water is not a bad idea. You would need to tape a something thin over the sound hole, put it in a non-leaking plastic trash bag and submerge in something large enough to dunk tail first up to the neck joint. A 50 gallon drum ought to do it.

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Joe Beaver
Maker of Sawdust

To find the area of the soundboard, you could cut the shape out of a piece of mdf, weigh it and then cut out a regular shape like a square to give you your mass per unit area

The helmholtz resonant frequency is not purely a function of volume and soundhole area; however, it seems you could get a fairly close estimate of the interior volume of a guitar body by changing the soundhole area.

I'm at work and don't have the equations in front of me......but couldn't you measure the resonant air frequency of the body, then tape off half the soundhole area and re-measure the resonant air frequency. Since the back/top stiffness are the same for both measurements, I'm guessing you could make a few assumptions and use the change in soundhole area and the change in frequency to calculate the interior volume of the guitar. It wouldn't be exact, but no other method mentioned previously is exact either (for example measuring the volume of the esterior of the guitar vs the interior volume).

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Formerly known as Adaboy.......

If you have the means to do that then you probably already have the guitar modeled in a fairly high end piece of software...in which case you push a button and it tells you the volume.

Truly...you could pay for the service described above...and pay at least a couple of hundred bucks for it.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I am late to this party but I had this idea when this discussion was fresh. One could simply bend a couple of sides out of some easy to bend white oak, or use bending ply and attach to a 3/4" cutout of the guitar shape. So, no top to the thing. You could nail and glue or use what ever method you want to attach and fill with water. Yes the plywood is flat but the loss of volume because of no dome would offset a bit that there is no bracing. It would be close and good enough for comparisons between body styles. One could block the moat thingie (that is what I'm calling it) up to account for taper. Leave the sides high and you could fill it more or less to determine how the volume changes with a deeper box or shallower box. Make some marks on the inside at a few intervals and you could fine tune for different depths at the neck on butt.
L.

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Cut to size.....Beat to fit.....Paint to match.

basic , width x length x thickness at the " approx " offset of the curves to account for average , will get you close enough for the girls we hang out with !

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OK, Here's the way...
Liquid will fill all the voids and give the most accurate results, but water directly on wood is not such a good idea.
So, use Mercury! Put the guitar on a scale & zero it out, fill it up through the soundhole, and read the scale. Multiply pounds by 2.0454 to get cubic inches.

If the previous volume numbers are in the ballpack, you'll need 5 or 6 hundred pounds of mercury....

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