Instructables

Homemade Cutaway Guitar - Of an existing one!

These are instructions how to make a homemade cutaway guitar of an existing one.

CAUTION: Not for beginners!

You must be able to handle with wood etc.

Get a guitar
http://www.ebay.com
http://www.ricardo.ch

A Guitar
http://en.wikipedia.org/wiki/Guitar

General documentation
Acoustics for violin and guitar makers
http://www.speech.kth.se/music/acviguit4/
 
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Step 1: What you need

Ok, here is what you need:

1 existing Guitar. (cheap one!)
1 Hotair gun
1 Saw (here japanese)
1 thin small saw (here a automatic). Needed for make small radius cuts. [german: Um sehr enge radien zu sägen.]
1 glue
1 paring chisel (small one, here 6mm) [german: Stechbeitel]

+ Lot of patient and time ;-)

Step 2: 1st do checking and draw a mask

First do checking if the cut is practical. If you can do it.

Check for parts witch must be cut off.
Check for parts inside the guitar.
Check also witch side. Left hand or right hand guitar differs!


Prepare a mask, a template. With paper or with transparent foil.

Draw with little dots the "cut route" on top and on bottom of the guitar.

Make sure, that you will saw better less material then too much!

Step 5: Bend


Bring water on the body side. With a spray.
After a minute or so, the body side is wet and very easy to bend.

So you can just "open" the guitar, so that you can look inside it :-)
sartor3 years ago
This mod will dampen your guitar's resonance and tone! That wood is there for a reason.

A test to see how much the soundboard's resonance affects the sound of a guitar: put a guitar on your lap and strum the open strings. Listen to the vibration, sustain, overtones, etc. Now press your other palm down on the soundboard (not too hard, as you don't want to damage it) and strum again. Hear the difference? Try this with the sides and back, too.

If you MUST have a cutaway (do flat-top guitars sound good that high up anyway?), consider a Maccaferi-style that's not too invasive:

http://upload.wikimedia.org/wikipedia/commons/7/7c/Guitares_type_Selmer_Maccaferri.jpg
looperted3 years ago
Thats the same guitar i have if its an alvarez! =P
LasVegas7 years ago
How severely did this effect the acoustics of the guitar? I'm assuming, being a very inexpensive guitar, it didn't have much quality to start with...
michi (author)  LasVegas7 years ago
As far as I know, the "acoustic" (tone, sound) will be mainly generated by the strings. Yes, this was and is just a test to see, if this modification is possible. I don't know if anyone else did this before. And, as you can see, it was a very inexpensive guitar. About CHF 60.- swiss francs. (Its EURO 40, $60? (what about the dollar? ;) So, just for doing things like that, go to ebay and pay a very cheap guitar.
mrmath michi7 years ago
I don't know much about acoustics, but I do know that the shape and structure of the guitar has A LOT to do with acoustics. Then again, I don't know if I would hear the difference.
michi (author)  mrmath7 years ago
I think it's like this: 1. string, tone will be generated with the strings. Best $9000 guitar with bad strings will not sound that good as a $90 guitar with good stings and tuned correctly. 2. top body , manly the top of the guitar inclusive connections (string-to-top). 3. rest. A cutaway is very similar like a normal one. If you change stings or change connection points (string-to-top) it has much more effect. You can also leave away the whole back bottom without that much difference. Sure, with more volume the sound will become more volume, better resonance for lower frequencies.
I'm sorry to criticize, but I have a degree in acoustics (and have also been a guitarist for 22 years), and I can tell you that you are completely wrong in your thinking. The tone of a guitar is produced by the properties of the internal air volume of the body as well as the construction qualities of the box. People think sound production in a guitar or piano is simply a matter of a vibrating string being amplified; this is not how it works. The string provides the initial "push" but much of the sound comes from resonances arising out of a complicated mass/spring-type problem involving the mass of air in the body cavity, as well as that of the bracing, the back, and neck, and is strongly dependent on that cavity's shape and the guitar body's construction. Your statement #1 about the $9000 guitar with bad strings versus the $90 guitar with good strings is not just untrue, it is factually impossible because of the differentces in construction.

Strings and connection points affect volume, partials and sustain greatly, but not so much the overall tone (at least, as long as you're not comparing strings with two completely different vibrational properties, like nylon vs. steel and wound vs. unwound or roundwound vs. flatwound.) I use the exact same set of D'Addario medium strings on my old beater Epiphone and my beautiful tobacco sunburst Simon & Patrick dreadnaught, but both guitars have a *completely* different tone from each other, owing to their different construction.

A lot of this can be found right in the "part 6" pdf on the acoustics page you linked to above (http://www.speech.kth.se/music/acviguit4/). (See in particular where it talks about how important the back and neck of the guitar can be to the resonances that shape the tone.)

Generally speaking, the smaller "bulb" of the guitar's body (near the neck) produces a high-frequenecy resonant peak, and the bigger bulb produces a lower peak. Together these produce a full sound. (This is why you rarely see "teardrop" shaped guitars, like an "A-style" mandolin.) Change the volume of one part of the cavity and you change the mass of the air that occupies the body, which shifts the resonant peaks and changes the tone. Ditto for removing mass or changing the shape of the front or back. Even the mass of the guitar's neck makes a difference. (See the PDF again. Or, if you want to try an expensive experiment sometime, stick a Stratocaster neck on a vintage Les Paul and see what it comes out sounding like.)

The reason cutaway guitars are more expensive than non-cutaway guitars is because of the extra work required to compensate for the acoustical losses of changing the body cavity volume and the area of the top, the necessary extra load-bearing bracing for the neck, etc. True, the losses may not be that huge to untrained people's ears, but they are there, and in a fine guitar it can create a noticeable difference.

These are not my opinion, they're simply the scientific facts of how sound production works in a guitar.

If your guitar sounds the same to you after doing this mod, I'd argue you probably have either a pretty cheapo guitar or a fairly untrained ear. Nothing wrong with that, except that it's incorrect to say on the basis of it that this won't change your guitar's tone.

The upshot is - thanks for this instructable, it's great (and a bold move!) but people should be warned not to do this to an instrument they care about, because the results will be unpredictable. Real cutaways are designed much more carefully than this, they're not just a regular guitar with a chunk taken out..
Where does one acquire a degree in acoustics? That sounds like an awesome field of work :D
The basic idea is very good, ans Iwill try it on one of my cheap guitar ( classical Spanish), Sure the tone will "move" but if you think twice when the guitar is open you can take à look at the "brassing" of the guitar and make it better, to add some high frequency. For the low end cutaway under $500.00US, they don't redesign al the guitar simply adjust the bracing and add/remove the cutaway. Over 800.00US now the guitar plan take in account that's will be a cutaway guitar. That's my point of view. Great Idea on cheap guitar but not for my Takamine ;-)
Strings are going to play a large role in tone etc. Similarly, reeds will do the same for woodwinds. Etc. etc. But the nice little resonant nodes that come from a great design make an instrument valuable.

Instrument materials, shape, construction will play a huge role in resonance (as you probably know). Sure, you can get decent sound out of almost anything by being a good player and using quality (not necessarily expensive) consumables. But comparing the same consumables on two different designs can show a big difference, if you know what to listen for :P But don't get me wrong, I spent a decent amount of money on a euphonium mouthpiece :P

Kinda like speakers.... Pay hundreds for the driver speaker... and a few dollars on an enclosure -- and you're not going to get as great a sound out of it. The Bose wave thingamabober is all enclosure (instrument), less driver (strings) - for example.


Nice instrucable though :)
you can have cheap speakers but a well built enclosure and the speakers will sound alot better than they realy are
Yep, that was my point :)
Come on michi, if this was the case there would be no difference between a Guarnerius violin and a "el-cheapo" one... The box does have an effect!
michi (author)  carlos66ba7 years ago
*lol* -
Yes sure. But on a existing one, the cutaway will not take affect strings and connection points etc. - Only shape and volume a little bit. So, the sound is nearly the same as before.
In fact, I was able to clean up and finish some wood splitting inside the guitar, witch did some noise before. ;-)
Wario6 years ago
I personally would not do this, it would deminish the value of the instrument. Besides, i don't notice a diffrence between the two types of guitar. Other then that a brilliant instructible.
Ramnosity Wario6 years ago
You said you did't notice a difference. I cutaway lets you get down to those really high strings. Mostly seen on electrics or electric-acoustics
Wario Ramnosity5 years ago
im actually used to reaching over the noncut region of the guitar.
me too
Wario Ramnosity6 years ago
Oh yeah, i forgot
sendez5 years ago
oh my god...poor guitar....
mrmath7 years ago
I'd be willing to bet that this would be a much better instructable in your native German. You speak far better English than I do German, by the way. I just mean to point out that there is no rule (that I know of) that says you have to post in English. A suggestion for the project. Perhaps a peice of string taped to the guitar to mimic its original outline would help in making the cut out the same length so when you bend the wood, it's the right length.
Good idea with the string...but a piece of flat plastic strap would work even better, and give you a smooth curve. Mark the end points of the cutaway, measure the strap against them, then bend it on the top of the guitar between the end points until you get a nice looking shape.
michi (author)  mrmath7 years ago
I don't know if there is such a rule. BTW, I just hacked in in about 10 minutes. (1st Project published here.)

  • The side is wood of the existing body side. So it's natural that there is about 3-5 cm missing on the neck side. Cause bending the side to a longer path will result in missing wood.
  • But there on the bottom I cut too much wood away. So, an idea is to have a wire or something like that with show as the curve.
Just make a better and precise template / mask. And don't cut that much wood. So you can cut away what is "too much" later.

In short: The curve outline on the bottom and top does need to be that precise. The curve will be done by the body side itself.

sploge6 years ago
this is cool but apart from looks why would you do it I know that a cut away is so that you can play high notes on the fret board but on a Spanish guitar the don't sound good I recommend buying a guitar with a cut out first of
wow, you really screwed up with the back edges! you should have sanded it down first, so they were smooth then used your wood, then filled, the sanded, and i would have added tung oil. maybe that's a bit too much work though?
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