Utile guitar?

[PeterF]

I am thinking about building my first guitar soon and I want to make it as cheap as possible so I can experiment with it and get used to the process before building a nice one. I really like the idea of using commonly available woods for guitars, like the shed guitar (viewtopic.php?f=25&t=3842), so I’ve decided to use douglas fir for the top and bracing and utile for the back sides and neck. I’ve found that the top should be 2.9mm for douglas fir, but how do I determine the thickness of the back and sides based on this wood? It has a specific gravity of 0.66.
Another question – I have access to a thickness planer not a sander. Is it safe to use it on wood this thin or would it tear chunks out of it?

[Allen]

Thickness question for sides for me is more a function of how heavy the wood is, tightness of bends and ease of bending. Some woods bend like cooked pasta, and others are just down right stubborn. For guitars I tend to look at 2.0mm for a starting point. Never more than 2.2mm and if it's something like a cutaway then it might go as thin as 1.7mm at least in the areas that require.

Backs again a function of weight and stiffness. Depends on whether I'm going for a stiff back or a responsive one. Usually they end up around 2.0 to 2.2mm, never more than 2.5mm

I fear that you will have disastrous results if you attempt to take veneers down this thin in a thickness planer. They tend to start to oscillate because they are so thin and the blades catch. Better to find someone with a thickness sander, or use hand planes and scrapers.

Please post progress shots of your build. We all love a build thread.

[seeaxe]

Hi Peter

From a relative newbie..

I agree with Allen, most of the planers I have seen have a minimum thickness of about 3 to 5mm and you will be taking a risk - depends how cheap your wood is..
If it has bottom rollers and top rollers, then the wood will bend and the ends will catch - with possible projectile results!

I dont know Utile but if it has irregular or reverse grain then I would not expect it to end well, whether or not you can get it thin enough. Careful planing or scraping will be the go if you cannot find a thickness sander to borrow

Having said all that, I have used a thickness planer to get kwila (very regular grain hardwood from the tropics down this way) back and sides down very thin (about 2mm). Mine is a "hobby" planer, 330mm, about the smallest one you can buy, of ubiquitous chinese design. I put a piece of MDF, wider than the wood I was thicknessing through the bottom of the planer and clamped it onto the flap down plates on either side. This lifts the blades away from the bed and gives a good solid base for the thin wood to bear on. The top drive rollers had no trouble sliding the wood over the bed. The ends did chip, so leave plenty of spare

And keep out of the way just in case!

PS You will find plenty of threads telling you to bite the bullet and use good woods even for your first guitar - you are probably going to do a lot better than you think. Plus, I dont know about others, but it takes me almost as long to get a decent finish on a guitar as it does to actually build - thats got very little to do with the wood. And the actual wood cost is probably not huge if you go for something reasonable and not AAAAAA+++ Brazilian Rosewood. I'd suggest at least buy yourself a good soundboard (google Torres and papier mache if you dont know that story already).

Good luck
Cymru am byth!

Richard

[Paul B]

I had the same idea when I started my first. I built a neck out of crap timber and did such a good job on it that I ditched it and started again with good materials. I'm glad I did. I'd regret it every time I looked at the guitar these days if I'd gone the cheap option. Now every time I look at the guitar I'm still happy with it and the cost of materials is no issue at all anymore.

You only ever build your first guitar once, why not max out your chances of making a good one by starting with good materials? You can get decent materials without spending a ton of money - Sapele back and sides, Western Red Cedar top, etc.

Here's a pic of my first:

[Trevor Gore]

I’ve found that the top should be 2.9mm for douglas fir...

Is that for generic douglas fir or for the piece you're about to turn into a guitar top?

"The book" has all the detail you need (far too long to quote here) of how to thickness the back as well as the top and what monopole mobility to aim for if you want a live back (irrespective of species), or how to make sure it is a non-live back, if that is what you want.

[PeterF]

Thanks for the advice. The real reason for going cheap is that I’m a student (boatbuilder), so can’t afford anything else! My college has quite a big stock of both these woods, so I can get them for practically nothing.
I got the top thickness from here: viewtopic.php?f=1&t=2546&hilit=douglas+fir
Utile is actually almost identical to mahogany, but slightly denser, so it should be quite good for a guitar, but I’ve never heard of it being used for one.
What type of glue is used for the top and back joints? I’ve heard that epoxy dampens the sound – is this true?

[Allen]

I use hot hide glue for almost all joins. Epoxy is only used for work with carbon fibre and glueing the fret board to the neck so as not to add moisture to that join. Quite a few builders will use PVA glues. Titebond original is a favourite of many. LMI white glue gets the best reviews if you can afford the shipping from the USA.

[Paul B]

They should have some cedar too if you're building lapstrake boats, shouldn't they? I'd love to build boats. Guitars are easier to carry around tho.