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 Post subject: Removing backs...
PostPosted: Sat Nov 25, 2017 1:32 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
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First name: Ed
Last Name: Bond
City: Vancouver
Country: Canada
Focus: Build
Status: Professional
Once in a while I have to pull a back for one reason or another.

Yesterday was such a day, and, once again, I had trouble with the seams opening up on the head and tail block. Fortunately, I can use the back to make a smaller guitar and salvage it, but I'm curious as to how others do it?

I wonder if there's a way to do it without using heat? For that seems to be the problem for me. I can get a fairly clean removal all way round til the blocks, and then by the time there is enough heat to soften the glue to get the knife through, the seams have opened up, the wood has changed shape slightly, and the seams no longer fit together. This has happened pretty much every time...

Any tips?


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 Post subject: no tip, a dumb question
PostPosted: Sat Nov 25, 2017 1:49 pm 
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Cocobolo
Cocobolo

Joined: Mon Feb 13, 2012 8:49 pm
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First name: peter
Last Name: havriluk
City: granby
State: ct
Zip/Postal Code: 06035
Country: usa
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Status: Amateur
Would this all go happier if the guitar body was back in a mold? And the seams (I'm guessing the seams are those where the sides butt against each other at the neck and heel) are insulated from the heat that is releasing the back glue?

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 Post subject: Re: Removing backs...
PostPosted: Sat Nov 25, 2017 3:59 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
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First name: Ed
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Country: Canada
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I don't see how putting it in a mood would insulate it...


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 Post subject: Re: Removing backs...
PostPosted: Sat Nov 25, 2017 4:05 pm 
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Contributing Member
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Joined: Sat Aug 27, 2011 1:59 pm
Posts: 180
First name: Ken
Last Name: Lewis
City: Mt. Pearl
State: NL
Country: Canada
Focus: Build
Status: Amateur
Ed, You'd need to put on some music maybe?



These users thanked the author Ken Lewis for the post: Hesh (Sat Nov 25, 2017 5:33 pm)
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 Post subject: Re: Removing backs...
PostPosted: Sat Nov 25, 2017 4:18 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Sun Mar 30, 2008 8:20 am
Posts: 2187
Hi Ed,
One more place an oscillating tool comes in handy. The thin blade and ability to plunge cut allows you to saw through the blocks and lose a minimum of body depth. After removing the back you probably clean up the sides and linings on the radius dish to remove glue and such so the blocks can be reprofiled at the same time.


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 Post subject: Re: Removing backs...
PostPosted: Sat Nov 25, 2017 5:22 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
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First name: Ed
Last Name: Bond
City: Vancouver
Country: Canada
Focus: Build
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Ha ha Ken,

Random stoner rock has been on constant rotation. I only recently discovered stoner rock at the tender age of 44, turns out it's my jam, other than the fact that I don't get stoned...

Clay, that actually seems like a pretty good idea...


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 Post subject: Re: Removing backs...
PostPosted: Sat Nov 25, 2017 7:45 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
Posts: 2567
If it was glued with hide glue the front should crack off with some careful tapping with a thinned out spatula. Once you get a little opening up around the edges, it should work. You want to span the center seam glue joint with the spatula when you finally get to that area and the rest is loose. Slow going is the ticket. Never use heat around center seams. The tailblock should be tapered to kerfing width.

Image

I can't begin to tell you how many folks don't do the taper on the tail block and what a difference it makes. No telegraphing from a wide block with bad humidity care. I was toying with the idea of doing the same on the dovetail block at the bottom before I quit.
A big question is "Is the neck on yet?" Might make it a little easier. The Idea of using an ocillating tool with a very thinned out blade is a good idea too.

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http://www.brentrup.com


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 Post subject: Re: Removing backs...
PostPosted: Sat Nov 25, 2017 8:05 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
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First name: Ed
Last Name: Bond
City: Vancouver
Country: Canada
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Nope, no neck yet. I do taper the block at the top but not at the back. Titebond is the glue.


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 Post subject: Re: Removing backs...
PostPosted: Sun Nov 26, 2017 10:44 am 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
Posts: 2567
Yeech, Titebond...rubbery and "creepy".
Use an oscillating tool and grind the blade thin.

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J. Brentrup Guitars & Mandolins
http://www.brentrup.com


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 Post subject: Re: Removing backs...
PostPosted: Sun Nov 26, 2017 4:36 pm 
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Contributing Member
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Joined: Sat Sep 14, 2013 9:46 pm
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Location: Napa Valley
First name: David
Last Name: Foster
State: CA
Zip/Postal Code: 94558
Country: USA
Focus: Build
Status: Amateur
Whats your method for heating up the seams? I route the bindings off first then remove back and/or top an heating up a spatula then slowly separating the joint along perimeter. The spatially is very small. so its doesn't spread the heat around. fyi I use a torch to heat spatula.


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 Post subject: Re: Removing backs...
PostPosted: Sun Nov 26, 2017 5:22 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Sun Mar 30, 2008 8:20 am
Posts: 2187
They also make scraper blades for oscillating tools - makes it like a power putty knife. I have sharpened them to a knife edge and used them to separate glued joints in furniture. Maybe a little less invasive than the saw blade, but maybe a little more chancy.


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 Post subject: Re: Removing backs...
PostPosted: Sun Nov 26, 2017 5:41 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
Posts: 4753
First name: Ed
Last Name: Bond
City: Vancouver
Country: Canada
Focus: Build
Status: Professional
I generally use an iron...


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 Post subject: Re: Removing backs...
PostPosted: Sun Nov 26, 2017 9:32 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Sun Mar 30, 2008 8:20 am
Posts: 2187
"I generally use an iron..."

Not a bad way to go - unless you have a laminated back gaah


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 Post subject: Re: Removing backs...
PostPosted: Sun Nov 26, 2017 10:25 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Feb 20, 2008 7:15 pm
Posts: 4753
First name: Ed
Last Name: Bond
City: Vancouver
Country: Canada
Focus: Build
Status: Professional
Never used a lam back and don't see it in my future:)


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