Official Luthiers Forum!

Owned and operated by Lance Kragenbrink
It is currently Fri Mar 29, 2024 1:48 am


All times are UTC - 5 hours


Forum rules


Be nice, no cussin and enjoy!




Post new topic Reply to topic  [ 14 posts ] 
Author Message
PostPosted: Sun Apr 22, 2018 6:42 pm 
Offline
Koa
Koa

Joined: Tue Jul 22, 2008 9:34 pm
Posts: 507
Location: ottawa, ontario, ca
First name: Mike
Last Name: McNerney
City: Ottawa
State: On
Country: Ca
Focus: Build
Status: Amateur
I baked a top yesterday for my 12 string & will bring it down to .125 how long do I wait before glue up & bracing?
Mike

_________________
Mike McNerney


Top
 Profile  
 
PostPosted: Sun Apr 22, 2018 7:29 pm 
Offline
Contributing Member
Contributing Member
User avatar

Joined: Thu Feb 09, 2006 2:35 pm
Posts: 2951
Location: United States
First name: Joe
Last Name: Beaver
City: Lake Forest
State: California
Focus: Build
I wait until the top becomes stable. It should returned to pretty much the same flatness as before it was baked. I like to sticker it top and bottom and apply some weight just incase it forgets what it should look like.

_________________
Joe Beaver
Maker of Sawdust



These users thanked the author Joe Beaver for the post: mikemcnerney (Mon Apr 23, 2018 9:15 am)
Top
 Profile  
 
PostPosted: Sun Apr 22, 2018 9:37 pm 
Offline
Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
Posts: 7221
First name: Ed
Last Name: Bond
City: Vancouver
Country: Canada
Focus: Build
Status: Professional
Bring it to your climate control/build area and weigh it. Once the weight remains constant it should be acclimated.



These users thanked the author meddlingfool for the post: mikemcnerney (Mon Apr 23, 2018 9:15 am)
Top
 Profile  
 
PostPosted: Mon Apr 23, 2018 8:40 am 
Offline
Brazilian Rosewood
Brazilian Rosewood

Joined: Tue May 13, 2008 10:44 am
Posts: 6232
Location: Virginia
That's what I do too. I just weigh it and write down the weight right on the top. Then the next day weigh it again and so on. It's always nice to have plenty of time but it will probably be stable in a week.



These users thanked the author jfmckenna for the post: mikemcnerney (Mon Apr 23, 2018 9:15 am)
Top
 Profile  
 
PostPosted: Mon Apr 23, 2018 10:23 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Feb 12, 2009 12:12 pm
Posts: 3290
First name: Bryan
Last Name: Bear
City: St. Louis
State: Mo
Country: USA
Focus: Build
Status: Amateur
I've only done this once and it was with a top resawn (1/4" thick) from a board at the big box store. No telling how wet it was when it started. I baked it a few times clamped down with stickers. I let it set in the shop for about a week and it never moved. Thinner stock may take less time to acclimate but why rush it? It is going to be really dry when it comes out of the oven.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.


Top
 Profile  
 
PostPosted: Mon Apr 23, 2018 12:25 pm 
Offline
Contributing Member
Contributing Member

Joined: Sat Aug 27, 2011 1:59 pm
Posts: 374
First name: Ken
Last Name: Lewis
City: Mt. Pearl
State: NL
Country: Canada
Focus: Build
Status: Amateur
I'm curious. Talking about tops, what happens with the weight after baking? Does it lose or gain going from the bake
to room condition. I 'm assuming it"s not green just before baking. My thinking is that baking would remove all residual
moisture and what's left would be immeasurable. I haven't done any baking, so gimmie the low down please and thanks.
Ken



These users thanked the author Ken Lewis for the post: Bryan Bear (Mon Apr 23, 2018 1:22 pm)
Top
 Profile  
 
PostPosted: Mon Apr 23, 2018 12:47 pm 
Offline
Contributing Member
Contributing Member
User avatar

Joined: Fri Jul 10, 2009 4:44 am
Posts: 5398
First name: colin
Last Name: north
Country: Scotland.
Focus: Build
Status: Semi-pro
IME, specific gravity (density) goes up, as does stiffness.
(Edit to clarify - Wood acclimatised to 43% RH, then baked, and then re-acclimatised to the same 43% RH)

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


Last edited by Colin North on Mon Apr 23, 2018 3:07 pm, edited 1 time in total.

Top
 Profile  
 
PostPosted: Mon Apr 23, 2018 1:29 pm 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Feb 12, 2009 12:12 pm
Posts: 3290
First name: Bryan
Last Name: Bear
City: St. Louis
State: Mo
Country: USA
Focus: Build
Status: Amateur
Ken Lewis wrote:
I'm curious. Talking about tops, what happens with the weight after baking? Does it lose or gain going from the bake
to room condition. I 'm assuming it"s not green just before baking. My thinking is that baking would remove all residual
moisture and what's left would be immeasurable. I haven't done any baking, so gimmie the low down please and thanks.
Ken


I am, by no means, an authority on this but. . . I think your question is will the wood gain weight after you bake it. I think the answer is yes. Baking will drive out most of the water and that wood will have to acclimate to normal conditions so it should gain weight as it gains water. My understanding is that wood that acclimates to a given RH will have slightly less water if it is gaining moisture to acclimate than if it is losing water (I'm not sure how much). But, you should be able to say that if it is no longer gaining weight, it has stabilized to the shop RH.

If your question is more about what happens to the wood due to the baking process, that is a more complicated answer and I KNOW I shouldn't be tackling that one. . . I'll be interested to read the responses from those who know though!

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.


Top
 Profile  
 
PostPosted: Mon Apr 23, 2018 9:35 pm 
Offline
Contributing Member
Contributing Member

Joined: Sat Aug 27, 2011 1:59 pm
Posts: 374
First name: Ken
Last Name: Lewis
City: Mt. Pearl
State: NL
Country: Canada
Focus: Build
Status: Amateur
"IME, specific gravity (density) goes up, as does stiffness.
(Edit to clarify - Wood acclimatised to 43% RH, then baked, and then re-acclimatised to the same 43% RH)"

So... if I bake a top panel that's weighs 200 grams it will weigh more once returned to 43% RH. Or do the dimensional
quantities change? I guess the question I'm asking is, what is the variable that causes density to go up?


Top
 Profile  
 
PostPosted: Tue Apr 24, 2018 3:06 am 
Offline
Contributing Member
Contributing Member
User avatar

Joined: Fri Jul 10, 2009 4:44 am
Posts: 5398
First name: colin
Last Name: north
Country: Scotland.
Focus: Build
Status: Semi-pro
Shrinkage.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


Top
 Profile  
 
PostPosted: Tue Apr 24, 2018 8:14 am 
Offline
Contributing Member
Contributing Member
User avatar

Joined: Thu Oct 07, 2010 5:28 pm
Posts: 687
First name: Casey
Last Name: Cochran
City: Gainesville
State: GA
Zip/Postal Code: 30501
Country: USA
Focus: Build
Colin North wrote:
Shrinkage.


"I was in the pool! I was in the pool!" ~George Costanza

_________________
Good judgement comes from experience. Experience comes from poor judgement.



These users thanked the author Casey Cochran for the post: Bryan Bear (Tue Apr 24, 2018 9:25 am)
Top
 Profile  
 
PostPosted: Tue Apr 24, 2018 9:56 am 
Offline
Brazilian Rosewood
Brazilian Rosewood

Joined: Tue May 13, 2008 10:44 am
Posts: 6232
Location: Virginia
From my deflection testing the stiffness didn't appreciably go up after baking. I have not measured density but I could see that going up. It will shrink but then it will come back too. In theory it will never come back to the size it was prior to going in the oven. My understanding of baking tops is that it's not so much a tonal thing but rather a structural or stability thing. It might make the wood more stable. It certainly does drive out the resins because you can see them bubble up to the surface. But it's nothing like torrafaction for example.


Top
 Profile  
 
PostPosted: Tue Apr 24, 2018 10:39 am 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Feb 12, 2009 12:12 pm
Posts: 3290
First name: Bryan
Last Name: Bear
City: St. Louis
State: Mo
Country: USA
Focus: Build
Status: Amateur
That's a good point about the resin. It sure did drive a bunch up to the surface the one time I did it. That alone should make the stiffness to weight ratio go up, I would think.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.


Top
 Profile  
 
PostPosted: Tue Apr 24, 2018 11:00 am 
Offline
Contributing Member
Contributing Member
User avatar

Joined: Fri Jul 10, 2009 4:44 am
Posts: 5398
First name: colin
Last Name: north
Country: Scotland.
Focus: Build
Status: Semi-pro
jfmckenna wrote:
From my deflection testing the stiffness didn't appreciably go up after baking. I have not measured density but I could see that going up. It will shrink but then it will come back too. In theory it will never come back to the size it was prior to going in the oven. My understanding of baking tops is that it's not so much a tonal thing but rather a structural or stability thing. It might make the wood more stable. It certainly does drive out the resins because you can see them bubble up to the surface. But it's nothing like torrafaction for example.

I agree. Basically I have baked tops to stabilise them as they were recently harvested. Brian Burns did extensive testing and found that baking improved Q, a measure of the resonant qualities of wood, but it seems to have vanished from the net. Any improvement in stiffness is small.
I believe that Collins and Taylor bake their tops, for stability.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 52 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