Construction materials

[akis tzortzis]

Hello, I am new here and have some basic questions.

Are the tops and backs of acoustic (or semi-acoustic) guitars usually made of thin plywood or is it a single thin sheet of wood? I would expect plywood to be much stronger.

If it were an archtop, would it be the same thin sheet of wood steamed/pressed into a curved shape? Or would be routed/curved out of a thicker piece of wood?

How are the sides made to obtain the shape? Are they steamed pressed out of a flat piece of wood or some other way of bending? I look at the grain where it curves a lot, and it seems that this is the case on my Yamaha 12 string acoustic.

I note another member has built an acoustic where there is a very strong wooden post/pylon connecting his bolt-on neck to the tailpiece end. I have also seen another user/maker simply bracing the soundboard (top) with lateral braces and using a tailpiece without any further strengthening - thereby depending on the soundboard to provide the necessary strength in addition to the sides of course. Which technique is more common and why?

Many thanks

[Dave Stewart]

... yes
Akis, suggest you spend some time browsing the MIMF Library. All your answers (& an ocean more) are there.

[Tony Costa]

Let me see if I can help you with your questions:

Hello, I am new here and have some basic questions.

Are the tops and backs of acoustic (or semi-acoustic) guitars usually made of thin plywood or is it a single thin sheet of wood? I would expect plywood to be much stronger.

It would be stronger and more stable as well. But it will also sound like plywood, i.e. bad. We use a book matched top so the wood is symmetrical across the center seam, but you can do it with one piece if you can find one big enough.

If it were an archtop, would it be the same thin sheet of wood steamed/pressed into a curved shape? Or would be routed/curved out of a thicker piece of wood?

Arch tops are carved from thick pieces of wood, not pressed into shape. Well...the cheap plywood archtops are pressed, but they are cheap and they sound cheap...usually.

How are the sides made to obtain the shape? Are they steamed pressed out of a flat piece of wood or some other way of bending? I look at the grain where it curves a lot, and it seems that this is the case on my Yamaha 12 string acoustic.

The sides are bent using heat, not steam. The sides are bent over a hot pipe, or using a heating blanket. There are tone of videos on YouTube showing the process. I even have one up there.

I note another member has built an acoustic where there is a very strong wooden post/pylon connecting his bolt-on neck to the tailpiece end.

Was this on a flat top acoustic, or an arch top? Was is on this forum? Can you link to it please?

I have also seen another user/maker simply bracing the soundboard (top) with lateral braces and using a tailpiece without any further strengthening -thereby depending on the soundboard to provide the necessary strength

A braced sound board is much stronger than you would think. Besides, if you think about it, even though the strings are pulling with 180# of force, it is not being applied to the sound board. The force applied to the soundboard is only a fraction of that 180# because of science and formulas and stuff. Stuff I have forgotten how to calculate on my own so I rely on the internets for help.
Assuming the strings pull with 180# of force, and the break angle over the bridge is 10 degrees, there is only a bit more than 31lbs of force pushing on the soundboard.

in addition to the sides of course.

The sides have nothing to do with the strength of the soundboard or its ability to not cave in under string tension on an archtop, or rip off from the pull of the strings on a flat top. The sides are only there to show off to other people how well you can bend thin pieces of wood. OK...they might be there for another reason as well, but it is not to strengthen the top.

Which technique is more common and why?

I would not say either technique is more or less common, it is just a style you like. I prefer to build flat top guitars because I like to play them. I don't play arch tops, so I don't care to build them. I also don't play electric, so I do not build those either.

Many thanks

Don't mention it, brother! That's what we are here for. Learning is a lot easier when you can ask a question and have it answered.

[Dave Stewart]

Learning is a lot easier when you can ask a question and have it answered.

.......but a lot more meaningful and rewarding when you at least make the effort to research out the answer yourself, rather than have others do the work & spoonfeed it to you.
Just different views on the value of education I guess Tony.

[Tony Costa]

Learning is a lot easier when you can ask a question and have it answered.

.......but a lot more meaningful and rewarding when you at least make the effort to research out the answer yourself, rather than have others do the work & spoonfeed it to you.
Just different views on the value of education I guess Tony.

I put a very high value on education Dave, and doing your own research is very rewarding. I also put a very high value on humor, and while my reply was not terribly funny, I did start out to make it funny. Unfortunately, some phone calls, and work stuff interrupted me and I lost my original funny thoughts.
In addition, I have always found it terribly annoying when people reply with "use the search function" instead of at least trying to help. It makes a new comer feel like what they are asking is beneath us and we can't be bothered answering. A full 100% of the time, before I ask a question on a forum, I have already used the search function and I was unable to find what I needed, usually because I was not using the correct query terms. IN the case of our new friend here, if he had searched for "a very strong wooden post/pylon connecting his bolt-on neck to the tailpiece end" he would have received this as a reply:
You specified too many words to search for. Please do not enter more than 10 words.

Shortening the search term to "wooden post/pylon connecting neck to tailpiece" would result in zero results until he posted his question. So the guy just does not know what he is looking for, and as a result, the search is useless to him. A similar Google search returns nothing related to guitars at all.
I might be new to this forum, but I am not new to the internet or forums in general. However, if we are trying to build a friendly community full of helpful people, we need to be just that. Helpful. At this point in the history of this forum, there is little reason to post any questions at all. We could all use the search function and we would almost never need to post new threads. What kind of community would that be?
So I say, post your questions. If it has been answered 100 times already, it will be answered 101 times. If a thread exists that discusses the question asked in depth, link us to that thread. Posting a question again might lead to a new viewpoint, or a new solution to a problem that nobody had ever thought of before. It wont happen often, but it will happen from time to time and when it does, it will be worth it. But, had we simply used the search, we would be stuck with the same old solution to a problem because we didn't want to revisit an old topic and have a fresh discussion on it. We certainly would not have people doing chadni testing if one guy didn't think that "tap tuning" had too many limitations for his taste and question the old methods. Granted, he may have asked the question of himself, but he asked it nevertheless. I think the reply of "use the search" discourages new members from posting and joining the group because it makes the forum feel like a high school clique that they are not part of and are not welcome to join.
Plus, it didn't even hurt one bit when I typed out my reply, so the only thing I lost was a few moments of time, but we may have gained a new member.

[akis tzortzis]

This is the thread showing on the second post pictures of the pylon/post. Please excuse me for using wrong terminology.

http://www.mimf.com/phpbb/viewtopic.php?f=5&t=2000

On another forum, another guitar maker posted pictures showing two acoustic guitars, one with tailpiece and one without, the one without used lateral braces and the one with a tailpiece used X bracing. But neither used a pylon to connect neck to tailpiece end block.

[Tony Costa]

I don't build arch tops, so I can't help you with this question, but I am sure the builder would explain why he did it if you ask him.
Same with the other two guitars you are wondering about. Without pics, it is hard to tell you why he did what he did. But asking the builder would certainly be a good place to start.

[Dave Stewart]

Tony, I guess I'm on the other side.... MIMF is a great forum that has done a huge amount of work to compile an extensive library for the very reason of answering these questions, novice to expert, up front! It should be USED! (For example, if you make the effort to at least go to the library & open GUITARS, PAGE 1, you'll see "Carved vs. bent vs. formed soundboards and backs" in the third line!)
So while you find it annoying to be pointed to the search engine, I find it very bad manners to expect others to take the time to explain it AGAIN because you can't be bothered to look it up. As my Dad would have said, "get off your ass & find out!"

[akis tzortzis]

I have already asked the maker to provide more info. I did not know that a library existed, sorry for asking newbie questions.

[Dave Stewart]

No problem Akis...we've all done it before realizing our answer was posted a week ago or in the library or whatever. (That was what I kind of suspected in my original post.)
FWIW (I've never built that style of archtop) "traditional" archtops use a tailpiece & have no "pylon" between head & tailblock. Clarks doesn't look full height so the top & back don't appear to touch (which means the underside of the top is also probably addiitionally braced).

[Tony Costa]

Tony, I guess I'm on the other side.... MIMF is a great forum that has done a huge amount of work to compile an extensive library for the very reason of answering these questions, novice to expert, up front! It should be USED! (For example, if you make the effort to at least go to the library & open GUITARS, PAGE 1, you'll see "Carved vs. bent vs. formed soundboards and backs" in the third line!)
So while you find it annoying to be pointed to the search engine, I find it very bad manners to expect others to take the time to explain it AGAIN because you can't be bothered to look it up. As my Dad would have said, "get off your ass & find out!"

To be fair, I only find it annoying when it is said over and over, and I agree that people should, as your father said, get off their arses and look". But sometimes, its nice to just get an answer to a question. I imagine we will see a bit of both.

[Mark Swanson]

Tony and Dave are both right and both have good points. Some new folks are not even aware of a Library Archive, and so may not have been there...and of course we are all about discussion here, and without it we can't bring any idea further than where it is in the Library.
So let's just hope we have more of both kinds of posts, with new folks getting help from both the Library and the active discussion which hopefully will come along too.

[Christ Kacoyannakis]

Akis,

Yia sou, file!

The library does have a lot of very good and useful information by many very expert and highly respected makers (some of whom have posted answers above). However, it may be difficult to get an overview of the entire construction process from reading the library. If you want to see the entire archtop building process, the most suggested book is by Robert Benedetto. He is a very successful maker, and also, a very nice man. He is very open with information as well. His book got a lot of us started in building archtops. There is also a DVD that you can buy to watch the guitar getting made. In addition, Frank Finocchio also has a DVD set on making an arcthop guitar. He uses a slightly different method (he steam bends a regular guitar top to an archtop shape, unlike Benedetto, who carvest the top and back out of solid wedges of wood). There are many different ways to make an instrument, each has its pros and cons, and some methods yield guitars which are better suited to certain situations than others.

Welcome to the MIMF.

[Paco Jimenez]

[...] But it will also sound like plywood, i.e. bad. We use a book matched top so the wood is symmetrical across the center seam, but you can do it with one piece if you can find one big enough.

[...] Arch tops are carved from thick pieces of wood, not pressed into shape. Well...the cheap plywood archtops are pressed, but they are cheap and they sound cheap...usually.

I have to disagree here. Laminated wood doesn't sound good or bad per se. Plywood is traditonally associated to budget factory guitars, hence the bad reputation. But it's the only reason why they sound bad. Penny pinching construction. It's all in the craftmanship. Well conceived and crafted laminated plates can make outstanding guitars and hand carved all solid plates can sound crap, thin, weak and poor. I've seen too many samples. A good laminated guitar can eat carved guitars for breakfast. Again, I've seen it so many times. My favorite ever archtop, after owning dozens of them, most of them hand carved, is a modest laminated '50s Bräuer made of 4-ply laminated woods molded into shape. Made of well selected tonewood spices veneers of different thicknes and densities to achive a high resonance and rich tone.

Using one piece plates is not a very good idea in terms of stability and long term durability.

Though not common in the States. Many European made archtops are built with very thick (up to 7 mm thick) solid spruce and solid maple plates pressed into shape. Some sound poor and some sound just excellent. Go figure.

Some others say that carving a recurve is the only way to get a good archtop having power and a good bottom end. Well, too many guitars prove the contrary. An easy example of this; just think of old Epis or current Parkers... And there's a whole lot more out there made from the '30s to these days.

Generalizations are often false and unfair.