Back & Sides Thickness?

[Bobby Westfall]

OK, my first post. I've built a few mandolins, 3 A models and finishing my first F5. I'm starting to build a dreadnought. I went to a place to have the sides and back thickness sanded to 0.095. I told the guy they could be a little thicker than that and it would be fine. (It's Indian Rosewood fyi) Anyway, he took the back down to around 0.080 and the sides to 0.075. Should I even bother with trying to use this at this thickness? Any thoughts or suggestions would be appreciated. Make a couple of rosewood Ukulele's?

[William F.Eden]

Bobby they would be to thin for me anyway. If you have to do any sanding they would be very thin. I try not to let them go under 100 then by the time you are done sanding they will be thin enoff.    Just my thoughts.Bill............

[Bobby Westfall]

Thanks Bill, that seems to be the general consensus of folks I've talked to. Any thoughts on what to do with this now?

[William F.Eden]

I would just keep it for some typ of smaller body Insturment like a Uke or Mandolin something that don't have a deep side to it . Just remember when you are haveing someone sand wood for you that when you check the thicknes of it and it is getting close to what you are looking for even if you don't change the sander any and you make another pass you will have it to thin. I would sooner hand sand some off the inside than end up with it to thin.   Just my Exp.   Bill...............

[Eric Steven Johansen]

In that no two pieces of wood are the same, I judge thickness somewhat by feel. If the piece still feels stiff enough I might use it. I've seen old Brazilian parlors with sides as thin as .060 and backs at .070. Although it works, the end result is a fragile guitar, susceptible to cracking and punctures that thicker woods might not experience. 

[Mark Pollock]

You could always laminate a really thin piece of something else inside and go with it - nothing wrong with lamination, and it can make the sides really strong as well. (I suppose you could laminate something on the outside, and just tell people about how decadent the guitar is.)

[Hesh Breakstone]

There are basically two schools (mainly with more than this) of thought regarding back function and consequently back thickness.  One school goes for "reflective" backs which are generally more massive (thicker) and braced for less if any movement.  The other school of which I personally build my own guitars with this thinking in mind is the "reactive" back.  A reactive back is often characterized by thinner plates and bracing that will let the back "pump" not unlike a fireplace bellows.

In the reactive back camp .080 is fine and many of the guitars that I have built have backs this thin.  Be advised though it's very easy for builders to embrace an idea that we are exposed to perhaps via the Internet and not understand that there is more to the "system" than plate thickness.  As Eric said the stiffness of an individual back plate is what's really important not any spec thickness.

When I build with reactive backs my back bracing changes accordingly to wider (more gluing area), lower, more flexible braces.

If the person who did the thickness sanding did not stop at say 80 grit and you will still need to take it down say .003" to get rid of scratches AND if the individual piece of EIRW is pretty stiff AND if you brace accordingly it might be fine.  Lot of "ifs" though...eh.

.075 for sides is fine too in my opinion again if the individual sides are pretty stiff, the species AND your bending methodology are likely to not induce any cupping and again if the final grit used for thicknessing was not so abrasive that you have to remove a lot more material these sides could be fine too.  In addition to side tapes many of us also use strategically placed side supports if we have any concerns.

It's right on the line as to if I would use it for a dread.  But if not a smaller body guitar would be fine with these plates.  

[Glen H]

W Cumpiano was asked the same question recently. You might read his opinion.

 

Cumpiano entry

 

[Bobby Westfall]

Good advice. I may make a parlor model, or some ukuleles. I appreciate every ones feedback. Very generous of you all. Thanks

[Doc Scantlin]

I just measured an original mahogony side from a 1918 Martin 00-18. It ranges from .050" to .030" thick. Of course it is a gut string, smaller model than yours but that's quite a bit thinner than the thicknessess being discussed. The top is .090" (at the sound hole) and I don't know the thickness of the back. According to Chuck Traeger, even a double bass should ideally have sides as thin as .080". I actually like around .070" for guitar sides...I think your wood is fine. Back has braces, sides have cloth strips...

[Donald A. Fortune]

Hi Bobby- I size my sides at 3 mm or .118 and haven't had any problem with them be it a classical or otherwise.

just my 2 cents-- peace, Donald

 

[Hesh Breakstone]

One of the great things about Lutherie is that we are free to do what ever we wish provided that... we are also ready to accept responsibility for the outcome. ;)

Once upon a time there was a little company trying to make a guitar and they used sides in the .055" range and backs just a bit thicker.  Although these guitars are not to be found in every player's arsenal some of them did go on to fame and glory in the hands of folks such as Tony Rice.

Here's a very good post by Tim McKnight who is a fantastic Luthier and really knows his stuff:  Side and Back Thickness Post

My only dog in this hunt is the idea that there is no correct answer here.  As mentioned what works is more a function of species and stiffness as well as bending technique and intended purpose as well as a few other concerns that come to mind.  If folks prefer beefier plates/sides more power to em.  Likewise and this is the point thinner plates and sides like most if not nearly all ideas in Lutherie is nothing new and has been done before with great success if you have priced a decent pre-war Martin lately.

Even today and although Ervin Somogyi uses "double-sides" for his sides his tops can be .060"!  Heresy you may say?  Ever price a Somogyi guitar or better yet play one - heaven!