StewMac tools

Joining the Top

Please put your pickup/wiring discussions in the Electronics section; and put discussions about repair issues, including fixing errors in new instruments, in the Repairs section.

Joining the Top

Postby Michael Baresi » Sun Jul 09, 2017 6:33 pm

I read somewhere that joining the top with the wide grain at the center line will increase bass response.
Does anyone know if this is true or not true?
Any advantage or disadvantage to doing this?
User avatar
Michael Baresi
 
Posts: 98
Joined: Sat Jul 13, 2013 12:36 pm
Location: Mesa Arizona

Re: Joining the Top

Postby Barry Daniels » Sun Jul 09, 2017 8:13 pm

My BS meter pegged out on that one.
MIMF Staff
Barry Daniels
 
Posts: 1680
Joined: Thu Jan 05, 2012 10:58 am
Location: Houston, Texas

Re: Joining the Top

Postby Rodger Knox » Mon Jul 10, 2017 1:30 pm

I'm with Barry. Joining a top with the wider grain in the middle will increase the width of the grain in the middle, any other effects are merely coincidental.
A man hears what he wants to hear, and disreguards the rest. Paul Simon
Rodger Knox
 
Posts: 477
Joined: Mon Jan 09, 2012 2:02 pm
Location: Baltimore, Maryland

Re: Joining the Top

Postby Randolph Rhett » Mon Jul 10, 2017 2:34 pm

I think you've been pranked, but I can't be sure. At the school, whenever anyone makes a mistake or there is an "oops" with a tool we say it was done to "increase bass response". I don't know if that is a joke just with us or whether that came from the broader luthier community.
User avatar
Randolph Rhett
 
Posts: 246
Joined: Mon Aug 06, 2012 5:19 pm
Location: San Diego, CA

Re: Joining the Top

Postby Brian Evans » Mon Jul 10, 2017 3:36 pm

There is widespread discussion, from Frank Ford to Symogi to Larivee, that all other things being equal (they never are) a wider grain top would tend to emphasize bass response more than the exact same instrument made with fine grain. The idea being that the wider grain would be more flexible than the narrower grain. But then again anyone who can deal with such detail can also deal with slight differences in stiffness of the top, I would imagine. So I rate this as more than internet trolling, more than an old wive's tale even, but less than proven. Someone decided (probably the same guy who decided that guitars should have perfectly mirror polished finishes) that very high grain count was the hallmark of excellent top wood. At the same time, many excellent instruments have been made with wide grained wood. I personally tend to put the tighter grain in the middle, under the probably wrong idea that it is stronger and the middle is the region of maximum stress. Plus I think it looks better.
Brian Evans
 
Posts: 507
Joined: Sat Aug 30, 2014 8:26 am
Location: Tatamagouche, Nova Scotia

Re: Joining the Top

Postby Barry Daniels » Mon Jul 10, 2017 3:49 pm

Tighter grain is not always stiffer than the wide grain.
MIMF Staff
Barry Daniels
 
Posts: 1680
Joined: Thu Jan 05, 2012 10:58 am
Location: Houston, Texas

Re: Joining the Top

Postby Alan Carruth » Mon Jul 10, 2017 3:52 pm

As Brian says, the 'standard model' has it that wider grain spacing yields lower cross grain stiffness, and a more flexible top at a given thickness. The best data I'm aware of says that if there is such an effect, it's small, and restricted to the extreme case, where you're looking at three or four grain lines to the inch. Even then, it would only hold for wood where the dark latewood lines are abnormally narrow relative to the overall grain spacing. At any rate, in the measurements I've made that whole effect is simply swamped by changes in the degree of quarter. The quickest way to lose cross grain stiffness is to cut the wood so that the annual ring lines are not perpendicular to the surface. You can get measurable changes in cross grain stiffness for changes in the angle that you can barely see.

Which brings up a thought about how the whole legend may have gotten started. Back when I started out most guitar top wood was leftovers from the folks who cut wood for 'cellos. They would cut the 'cello tops to get the best quarter over as much width as possible, which means that the cut lines went right along the radii of the tree (assumed to be a cylinder). If you make cuts parallel to one of those radii, you'll see that the ring angle along one edge can stay pretty close to perpendicular to the surface, but at the other edge, usually toward the center of the tree, the ring lines go off quarter. This alone is enough to change the grain line spacing so that it looks wider, and, of course, most trees have wider ring spacing in the center anyway. This cut gives a distinct lack of cross grain stiffness where the grain spacing is wide, but the wide spacing is not the cause of the low stiffness, it's just a sign that the wood was not properly cut for the application. These days you seldom see guitar top wood like that, since there are dedicated suppliers who avoid doing it. Just speculation.
Alan Carruth
 
Posts: 729
Joined: Sun Jan 15, 2012 1:11 pm

Re: Joining the Top

Postby Michael Baresi » Mon Jul 10, 2017 4:32 pm

Some very interesting responses. Thanks
I agree with Brian that tight grain in the center looks better so I will continue to join that way.
I'm building a parlor and hoping to find a way to increase my bass.
As we all know you can't believe everything you read on the internet.
User avatar
Michael Baresi
 
Posts: 98
Joined: Sat Jul 13, 2013 12:36 pm
Location: Mesa Arizona


Return to Flat-Top Acoustic Guitars and Bass Guitars

Who is online

Users browsing this forum: Aaron Helt, Bing [Bot] and 3 guests

Your purchase from these sites helps support the MIMForum, but only if you start at the links below!!!
Amazon music     Amazon books     Amazon tools     Rockler tools     Office Depot    

The MIMF is a member-supported forum, please consider supporting us with a donation, thanks!
 • Book store • Tool store • Links •