Official Luthiers Forum!

Owned and operated by Lance Kragenbrink
It is currently Thu Mar 28, 2024 9:43 am


All times are UTC - 5 hours





Post new topic Reply to topic  [ 18 posts ] 
Author Message
 Post subject:
PostPosted: Sat Jan 05, 2008 5:58 pm 
Offline
Walnut
Walnut

Joined: Tue May 22, 2007 11:28 am
Posts: 12
Location: United States
Hi guys. I have been thinking alot about thickness graduation on the
sound board and hoe this effects tone. Can you guys share any info on
this, opinions, history of it, measurments, anything you have to shed light
on this topic.
thank you
avilaguitars


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jan 05, 2008 11:39 pm 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Aug 18, 2005 2:21 am
Posts: 2924
Location: Changes when ever I move..Australia
Focus: Build
Status: Amateur
bump


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jan 05, 2008 11:50 pm 
Offline
Old Growth Brazilian Rosewood
Old Growth Brazilian Rosewood
User avatar

Joined: Fri Nov 02, 2007 9:49 am
Posts: 12971
Location: Ann Arbor, Michigan
First name: Hesh
Last Name: Breakstone
City: Ann Arbor
State: Michigan
Country: United States
Status: Professional
Admittedly I know very little about this but something that may be helpful to you is what Taylor Guitars does.  Taylor mills a thinned ledge around the perimeter of at least the lower bout, not sure if this extends around the upper bout.  This thinned area of the top is IMHO is not so much to impact tone as it is to permit greater flexibility of the top, around the perimeter permitting the top to move more.  This would in my view have more impact on volume.

Many builders here, myself included, do something toward a similar end and that is to simply thin the top, once on the rim, around the edges of the lower bout.  We are looking for a very slight amount of flexibility in the top when we take our thumbs and press with moderate pressure in the bridge area.

I learned this from my pal Lance K. and it seems to indeed open up the guitar a bit.

Hopefully someone will post a link to the info on what Taylor does and why to help you out.


_________________
Ann Arbor Guitars


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 12:03 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Aug 18, 2005 2:21 am
Posts: 2924
Location: Changes when ever I move..Australia
Focus: Build
Status: Amateur
Have a look HERE you want to follow the "Factory Friday" link and I think it is video 7 on the second page.

Cheers

Kim


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 1:46 am 
Offline
Koa
Koa

Joined: Mon Jan 03, 2005 10:29 am
Posts: 556
Location: United States
I would reccomend getting a Hacklinger Gauge
http://www.stewmac.com/shop/Tools/Measuring_tools/Hacklinger _Thickness_Gauge.html

I disagree with hesh on this one, thinning the edge of the soundboard is all about tone and not volume.
stiffer is louder, more flex = more tone,
too much flex = mud puddle top.

the hacklinger gauge is a great tool which allows you measure the top, back, and side thicknesses of any already built instrument. I measure every guitar i get my hands on and make a note of the top back and side thicknesses.

also I think it`s important to remember that you thin the edges of a top when you sand your bindings flush. the gauge can tell you exactly how much you lost during that proccess and will help you get a handle on whats happening there.

Matt



Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 2:18 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Mon Dec 27, 2004 3:50 pm
Posts: 4662
Location: Napa, CA
Thanks, Matt...I think you're the first to ever tout the use of this gauge on the OLF. I like objective data. Over time and lots of measurements it can really shed some light on choosing a direction. How accurate would you estimate the Hacklinger measurements are compared to those of a digital caliper for example. I realize the kinds of measurements you describe can't be made with a caliper but am interested in knowing how accurately and repeatably the Hacklinger measures.

Any other info you can shed on your collection of measurements would be appreciated.

TIA

_________________
JJ
Napa, CA
http://www.DonohueGuitars.com


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 2:29 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Wed Jun 22, 2005 10:11 am
Posts: 2761
Location: Tampa Bay
First name: Dave
Last Name: Anderson
City: Clearwater
State: Florida
Zip/Postal Code: 33755
Country: United States
The Hacklinger thickness gauge is one tool I've been
wanting, But they are pricey ..Stew-Mac sells them for $ 385.00 !
Any other sources out there for this cool tool?

_________________
Anderson Guitars
Clearwater,Fl. 33755


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 3:33 am 
Offline
Koa
Koa

Joined: Mon Jan 03, 2005 10:29 am
Posts: 556
Location: United States
I had to trade my Taylor fret buck for mine!
but it was definitly worth the trade.

JJ, it is an extremely accurate precision tool.
the coolest thing about it, is how the magnet travels around over the bracing revealing more than just the thicknesses, but locations of the bracing, bridge patch, etc.
it`s really fun to use.

Matt


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 3:36 am 
Offline
Old Growth Brazilian Rosewood
Old Growth Brazilian Rosewood
User avatar

Joined: Fri Nov 02, 2007 9:49 am
Posts: 12971
Location: Ann Arbor, Michigan
First name: Hesh
Last Name: Breakstone
City: Ann Arbor
State: Michigan
Country: United States
Status: Professional
Matt my friend thanks for setting me straight on this.  I buy your explanation completely and just learned something - Thanks!

_________________
Ann Arbor Guitars


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 3:48 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Mar 22, 2007 10:59 pm
Posts: 2103
Location: Bucharest, Romania
Country: Romania
Focus: Build
Status: Professional
Dave, ive seen it in two other places for more than 400.  I sure want one too!




_________________
Build log


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 9:52 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Mon Mar 06, 2006 10:10 pm
Posts: 2476
Location: Argyle New York
First name: Mike/Mikey/Michael/hey you!
Last Name: Collins
City: Argyle
State: New York
Zip/Postal Code: 12809
Country: U.S.A. /America-yea!!
Focus: Build
Status: Professional
Thinning the edge is about tone & volume!
They actually go together in this area!

Mike

_________________
Mike Collins


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 10:06 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Mon Mar 06, 2006 10:10 pm
Posts: 2476
Location: Argyle New York
First name: Mike/Mikey/Michael/hey you!
Last Name: Collins
City: Argyle
State: New York
Zip/Postal Code: 12809
Country: U.S.A. /America-yea!!
Focus: Build
Status: Professional
To really open a can of worms we can discuss how stiff the top & braces are as a unit-then how the braces are tapered to the linings-the intended use for the guitar
(flat-picking,fingerpicking;etc.-classical?)
So many variables !!!!!

Mike

_________________
Mike Collins


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 10:16 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Mar 22, 2007 10:59 pm
Posts: 2103
Location: Bucharest, Romania
Country: Romania
Focus: Build
Status: Professional
Mike, what can you share about this issue on classicals.  Both the plate edge and the thickness of the outer fan braces and "V" closing braces. 

_________________
Build log


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 1:16 pm 
Offline
Koa
Koa

Joined: Mon Jul 02, 2007 1:22 pm
Posts: 766
The hacklinger (sp*) gauge is an important tool in my shop for measuring the graduation and thickness of fine vintage guitars that pass through my repair shop, for reproducing that graduation and checking that my new reproductions consistenly follow the graduation set by the vintage guitars. I only wish they made a imperial one!


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 3:15 pm 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Mar 01, 2007 3:15 pm
Posts: 2302
Location: Florida

I tried this on one guitar and was pleased with both the volume and tone of the guitar. It was a WRC top and not spruce. I purposly left the center of the top thicker than normal (~.140) and then thinned the outer edges of the lower bout to around .050. I wouldnt try this with spruce, but the wrc was so stiff it worked for me on that one. The guitar has loads of volume and the tone aint bad either.


I will mention that I progressively sanded the top from the bridge area to the outer edges of the lower bout and not just a ring around the edge of the lower bout. The upper bout remained at .140


I do something similar with my spruce tops, but not as drastic on the thicknesses. I have found that if you get too carried away and sand the top too thin, it will telegraph the braces through the finished top when you string it up. With spruce, think of sanding from .110 down to about .095 on the very edge of the lower bout ring. Any thinner and you are asking for big problems.


_________________
Reguards,

Ken H


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jan 06, 2008 3:25 pm 
Offline
Koa
Koa
User avatar

Joined: Mon Sep 12, 2005 12:40 am
Posts: 1900
Location: Spokane, Washington
First name: Pat
Last Name: Foster
State: Eastern WA
Focus: Build
Dave White posted awhile ago about a tool he conjured up to measure thickness. Maybe he'll pipe up.

_________________
now known around here as Pat Foster
_________________
http://www.patfosterguitars.com


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jan 07, 2008 8:23 am 
Offline
Brazilian Rosewood
Brazilian Rosewood

Joined: Sat Jan 15, 2005 12:50 pm
Posts: 3867
Location: United States
What I've found, so far:

Thinning behind the bridge tends to give a 'fuller' or more 'bassy' sound. Note that you can go pretty thin at the tailblock without compromising structural integrity.

Thinning in the 'wings', from the bridge ends out to the edges, but leaving the tailblock area thicker, tends to give a 'brighter' or 'more forward' sound.

One student of guitar acoustics (Bernard Richardson, who teaches Physics at the U of Wales in Cardiff), feels that thinning in the center would do more to increase output than thinning at the edges. This would most likely give a more 'bassy' and 'punchy' sound, similar to scalloping braces, and for the same reason. I have not tried this as yet, but see no reason to doubt it.

I feel that the critical area for stress on the top is between the bridge and soundhole, and usually leave my tops thick there.

The Taylor 'channel' should have a similar effect to thinning all around the perimiter: a bit more output without effecting the balance too much. It's a surrogate for tapering the graduation when that is hard to do owing to tooling costs. I have to wonder if that groove is not also a stress riser, and whether we'll see cracks in the lower bout edges from it over time.

The purfling rabbett also loosens the edge up a bit, and a wide purfling or narrow liners can act like thinning the edges to some degree.

Aside from these generalities, thinning the top in different areas lowers the pitches of the various top modes differently, and alters the relationships between them, and between the 'wood' and 'air' resonant modes. If, by thinning someplace, you move a 'wood' mode pitch to where it couples strongly with an air mode the sound of the guitar can change quite noticably, and it ways that are hard to predict from general rules. What works in this way for one person, or on one guitar, might not for somebody else or another instrument. That's one reason there seem to be so many exceptions to any set of 'general' rules.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jan 07, 2008 8:51 am 
Offline
Koa
Koa

Joined: Wed Aug 24, 2005 11:13 am
Posts: 1398
Location: United States
Tony, I would be very leery of basing reproductions on thickness measurements unless your top material exactly matches the stiffness and density of the original tops. This is the great trap that so many Strad copyists got caught up in. It's the wood plus the graduation (and bracing), not one independent from the other(s) that makes the tone and volume.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 18 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 12 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB® Forum Software © phpBB Group
phpBB customization services by 2by2host.com