Thicknesses you prefer on Parlor Guitars?

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Thicknesses you prefer on Parlor Guitars?

Postby Keith Walden » Tue Jan 22, 2019 5:44 pm

Im doing a Parlor based off my cheapi Ibanez guitar and was wondering what thickness woods you would recommend for Adi Top and Koa Sides?

Also, what thickness bracewood? I want it to ring and sing!!

Thanks
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Rodger Knox » Tue Jan 22, 2019 6:09 pm

That really depends on the specific pieces of wood you're using, but here's some ballpark numbers.
Top - 0.10" to 0.12"
Back - 0.08"
Sides - 0.07"
Bracing - 1/4" to 5/16"
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Keith Walden » Tue Jan 22, 2019 6:15 pm

Thanks Rodger, ballpark is good. I should have mentioned it will be Steel String. The MARTIN (I-18) Plans at gal site say its for (gut) strings, (but it is x-braced??)

http://www.luth.org/images/plans/pl08.jpg
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Bryan Bear » Tue Jan 22, 2019 10:53 pm

Take this with a large grain of salt. I have only made one parlor (very close to size 1) and the top was pine so. . .

I thicknessed it until it felt right; pretty stiff along the grain and just floppy enough across the grain. It ended up being 0.122” but I did sand the edges next to the bridge a bit more after the box was closed and bound. I was expecting to go much thinner but when it felt right, it felt right. On a box that small, the extra thickness doesn’t matter as much from a weight perspective. In the end, I was very happy with how it sounded. So much so that I am starting another one now. I think I have a thread here about it with pictures of the bracing and a sound sample if that helps.
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Keith Walden » Wed Jan 23, 2019 1:44 am

Right, the Cherry one, saw that.

How does that side soundhole effect the sound (when you plug it) is there a noticeble difference.
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Bryan Bear » Wed Jan 23, 2019 9:30 am

As the player, you can tell when it is covered. I couldn't tell any difference in sound from out in the room. Admittedly, I didn't do much testing on that front and I no longer have that guitar. The sound port is small (about 1.25" or maybe a little less) and I made the sound hole smaller (90mm diameter) to try and boos bass a bit. I also moved the sound hole closer to the heel at the cost of some frets.
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Alan Carruth » Wed Jan 23, 2019 12:55 pm

I thickness the top based on the size of the guitar, the expected load, and the Young's modulus of the wood along the grain. I'd be happy to go into details, but the point is that you need to make a measurement of the properties of the wood in order to know where to go with it. There's no way to tell just by looking. As it happens, the Young's modulus along the grain for softwoods pretty much tracks the density, and does so in the same way for all the species I've checked out so far. If you know the density you can predict the Young's modulus to within 10% plus or minus about 60% of the time. Increasing or decreasing the Young's modulus by 10% gives a change in thickness of about .004", so that's pretty close most of the time. Two things that will throw it off are run out or heavy latewood lines, which will make the Young's modulus lower than expected on the basis of the density. Really narrow latewood lines give wood that has a higher than expected long-grain Young's modulus: latewood adds more to mass than to stiffness. Red ('Adirondack') spruce does tend to be on the dense side, so it usually has a high Young's modulus and can be worked a bit thinner than, say, Engelmann, but that's an average. It's not at all hard to find a piece of Red spruce that will match an average piece of Engelmann, or vice versa, and I've even got Red spruce that matches WRC. Again, to be really sure, you need to make some sort of measurement.
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Freeman Keller » Wed Jan 23, 2019 1:00 pm

I have built three parlor sized guitars from the Antes plans, similar but different. The first was Sitka over EIR, it was a present for my daughter and I'm ashamed to say I screwed up when I built it. The Antes plans are drawn as tho you were looking thru the top with X-ray vision, every other plan I had used was drawn from the back, so my guitar ended up with the single tone bar running the wrong way - it is braced as tho it was a lefty. Funny thing, guitar sounds pretty darn good.

I built two more and got it right this time (pun intended). These guitars were built side by side out of sister cuts of Lutz spruce and same brace wood and neck, however one guitar is Brazilian rosewood, the other is Madagascar. Interesting thing is that when played side by side no one can tell a difference.

IMG_2970A.jpg


OK, lets answer your questions. The Lutz was pretty stiff and I had built a couple of guitars at 0.110 out of it, I thinned it a hair more for these guitars (lets say 0.105). The backs are 0.090, the sides bent well at 0.075 or 80. The Antes plans have a reputation for being over braced, I used 1/4 Sitka for mine, profiled the braces but did not scallop. A smallish maple b/p and pyramid bridge. One minor but maybe important consideration - all three guitars got Style 41 abalone purfling so they had a fairly substantial channel cut around the top edge - I've heard people say this might open the top response a little. Here is the bracing

IMG_2372.JPG


I'll add two more comments. These are amazing little guitars. While they don't have a huge bass they still are pretty well balanced and a joy to play. I had submitted one of them (the Mad rose guitar) to the Steel String Listening Session at the last GAL conference. As I was walking out of the auditorium a couple of fellows walked up and commented that they really liked my guitar and how well it projected. I asked them where they were sitting, they said the very back.

ps - you also asked about koa. I have built three koa guitars and bend them at exactly the same thicknesses as rosewood. Some koa is highly figured and I worried about it cracking when I bent the sides but turned out to not be a problem. Normal Fox bending setup and temperature.
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Jan Bloom » Wed Jan 30, 2019 11:50 pm

top should be .10 to .11
sides .07 to.075
back .075 to .08+

braces .25- tone bar(s) .20
finger brace(s) .20-

should be light, yes I use light gauge strings
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Re: Thicknesses you prefer on Parlor Guitars?

Postby Brian Evans » Thu Jan 31, 2019 11:04 am

You all mean the width of the braces/bars, not the height (which seems to always be tapered/scalloped one way or the other, yes? For fun, my archtop braces are 5/16" at the bottom tapered to 1/8" at the top, and around 5/8" tall at their highest, this on a 16" - 17" wide guitar.
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