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Semi-Hollow body questions
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=25997		 Page 1 of 1
Author:  Lemagr67 [ Wed Feb 10, 2010 10:59 pm ]
Post subject:  Semi-Hollow body questions
Hello all. My name is Matt and this is my first post here. To start with a little background, I'm an engineering student at the moment and have played guitar for about 10 years. I've always wanted to build my own guitar, and as fate would have it, I am allowed to build one for my senior deisgn project. I've been doing woodworking my whole life as well, so I'm thinking I might try to tackle a semi-hollow body. I am planning on buying Benedetto's book on the subject, but I have a few questions before I order it.

Firstly, does anyone know if this book covers SEMI-hollow body construction? Secondly, does anyone know of any other resources I could use to design the body of the guitar? I would prefer to use a template, but it's against the guidelines of my project. Thirdly, I am aware that a standard hollow body guitar is very touchy when it comes to the design of the body. Being that a semi-hollow is solid down the center, is the design of the body less sensitive to potetial "screw ups"? My hope is that the semihollow will be a little more forgiving if my design were to be less than perfect. I plan on making a few test runs out of cheap materials so I don't end up burning more expensive wood than I need to.

Thanks so much for any guidance here on my first build!
Author:  Parser [ Wed Feb 10, 2010 11:15 pm ]
Post subject:  Re: Semi-Hollow body questions
Hey, how's it going?

You can pretty much get away with murder on a semi hollow build. There really isn't much engineering in building a semi-hollow electric - it's more of a design exercise due to the fact that these things are so robust. If you need to engineer something - engineer how the location of the truss rod affects the stresses in the neck...and also the helmholtz resonance of the internal cavities versus the size of the f-holes (or whatever holes you'll be adding!).

My advise is to buy all the hardware, draw that up in the CAD system of your choice, and design the guitar around that. If you use a TOM bridge, or something similar, design the guitar with the bridge being set fairly low on the studs...and design the neck angle for the desired action height. Don't forget a ground wire to ground out the strings & bridge.

Good luck, have fun, and don't try to reinvent the wheel! :D

Trev
Author:  JohnAbercrombie [ Thu Feb 11, 2010 1:20 am ]
Post subject:  Re: Semi-Hollow body questions
Matt-
Welcome to the OLF!
On any given topic here, you will get lots of (often contradictory) opinions, so lots to think about!

I have the Benedetto book and DVDs and I don't think that is the resource you are looking for. The Benedetto book deals only with building (acoustic) jazz hollowbody guitars with carved top and back, and a neck set in a dovetail or tenon.

Most production semi-hollowbody (Gibson 335-style) guitars use laminated (molded plywood) tops and backs with a solid filler strip down the middle, and either a set (flat tenon glued in) neck or a bolt-on neck. You could certainly carve the top/back from solid wood, but it seems a bit of a waste of time and materials.

I don't know the 'research' aspect of your project, and that may control your choice of materials etc.

One book (which I haven't used) that I have seen recommended is
http://www.amazon.com/Building-Electric-Guitars-Hollow-Body-Semi-Acoustic/dp/3901314075/ref=sr_1_1?ie=UTF8&s=books&qid=1265868578&sr=1-1

If you need something to copy, you can find Chinese Epiphone 335 copies on eBay with broken necks pretty well any time you look.

Let us know how your project develops!

BTW, when is your deadline? Building your first guitar can take quite a bit of time....

Cheers
John
Author:  Ken McKay [ Thu Feb 11, 2010 8:20 am ]
Post subject:  Re: Semi-Hollow body questions
Lemagr67 if you email me I can send you a .pdf of a method for building a semi hollow guitar body. Be sure to include your log in name here and your real name so I can figure out how you found me. I get a lot of emails.

Ken
Author:  Fernando Alonso Jaén [ Thu Feb 11, 2010 9:05 am ]
Post subject:  Re: Semi-Hollow body questions
Hi Matt,

I have finished a semihollow recently, based on a hollow model. I wrote some notes on its design:

http://www.guitarrasjaen.com/English%20 ... Feder1.htm

At first my notes had a lot of detail, but I relaxed later.

This is the semi:

Image

It is the same guitar, but notice that the bridge doesn't have a wooden foot. The neck-to-body angle is the same, but the neck is a few milimeters deeper in its pocket to compensate for the smaller height at the bridge. These are photos of the body before being assembled:

Image
Image
Author:  Parser [ Thu Feb 11, 2010 9:39 am ]
Post subject:  Re: Semi-Hollow body questions
Nice work on the guitar...and on the Rhino modeling that preceded it!

Trev
Author:  Ken McKay [ Thu Feb 11, 2010 9:40 am ]
Post subject:  Re: Semi-Hollow body questions
I guess I would not consider that a semi-hollow body guitar, more of a chambered guitar. Nevertheless, it is beautiful.
Author:  Lemagr67 [ Thu Feb 11, 2010 1:59 pm ]
Post subject:  Re: Semi-Hollow body questions
Well the deadline isn't even posted yet. It will likely be about a year before it needs turned in. I've been able to figure most of the process out just from pictures, but there a few things that I still need to figure out. Specifically, designing the neck joint and finishing the instrument. Thanks to everyone that has pointed me in the right direction here.
Author:  Lemagr67 [ Fri Feb 12, 2010 10:47 pm ]
Post subject:  Re: Semi-Hollow body questions
Well, using some other guitars as reference, I have a rough outline for my first build. It's a semi hollow single cutaway... looks alot like a carparelli s3. I plan on drawing it up in solidworks tomorrow after I figure a few things out. Here are my problems:

1) What is the usual height of the arch for a guitar like this? Does anyone know of a resource where I might find some equations or guidelines for contouring the front and back plates?

2) I plan on using a set (tenon) neck. I have found a variety of designs for the neck joint but none point out exactly how they line up. From the side, with the nut to the left and the bridge to the right, would the rightmost end of the joint be vertical (mostly) like :::: or have a little protrusion from the bottom like ::::.. ? If the latter, is the protrusion meant to set under the hole for the first pickup?

3)Finally, roughly how thick are the plates and the sides meant to be?

I would like to just buy laminated plates, but they are premade so its a no no.

thanks again and sorry for the dumb questions
Author:  Ken McKay [ Sat Feb 13, 2010 6:17 pm ]
Post subject:  Re: Semi-Hollow body questions
1. About 12-14mm
2. Many schemes. Start with long arch and then make some cross arches. Use Curtiods or other type of curves.
3. Plan on setting the bridge height above the arch height 13mm or so plus the bridge height, depending on which type and then project the strings to get that angle. Figure in the overstand and neck tiltback to refine. Usually about 3.5 to 4 degrees.
4. plate thickness is very forgiving if you are laminating. Gibsons are variable from the old days. A general guide would be 3-4mm thick.

edit, I was in a hurry but wanted to get you something to go by. I will answer more comprehensively later.
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