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Putting the back on
https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=18048		 Page 1 of 1
Author:  SkyHigh [ Sun Jul 20, 2008 9:47 am ]
Post subject:  Putting the back on
My sides are currently in the mold with spreaders and I am ready to glue the back to the side and have couple questions.

Do you glue on the back with sides still in the outside mold? I ask because it's mohogany back/side and the pressure on the spreaders will be transferred over to back once I remove the spreaders(I'm guessing). The problem with this is that top has to be glued on without the spreader and thereore back and top will have different amount of pressure it's holding. Now It's obvious that top/backs primary role is not to act as a spreader or holder, but I feel that it's still part of structure that holds guitar together to certain extent and has pressure at some of the areas,right?

Also do you guys glue the side bracing or center strip first? I'm talking about the center piece inside the back that goes vertically between the braces.

thanks, David
Author:  Hesh [ Sun Jul 20, 2008 9:59 am ]
Post subject:  Re: Putting the back on
David buddy glue the back joint reinforcement to the back first.

Next attach the back to the rim with the rim in the mold and spreaders in place. The top can be attached first too, it is a matter of personal preference.

Now without removing the spreaders glue the top on last. Be sure that your spreaders can be disassembled and passed through the sound hole when both the back and top are glued on.
Author:  SkyHigh [ Sun Jul 20, 2008 10:02 am ]
Post subject:  Re: Putting the back on
Hesh wrote:
David buddy glue the back joint reinforcement to the back first.

Next attach the back to the rim with the rim in the mold and spreaders in place. The top can be attached first too, it is a matter of personal preference.

Now without removing the spreaders glue the top on last. Be sure that your spreaders can be disassembled and passed through the sound hole when both the back and top are glued on.


Hi Hesh,

When you say back joint reinforcement, you mean back braces?

Also, how do you go about pulling out spreader on the lower bout once box is closed?

Thanks, David
Author:  Hesh [ Sun Jul 20, 2008 10:17 am ]
Post subject:  Re: Putting the back on
David the back joint reinforcement is the strip that is glued onto the center seam of the inside of the back. The back braces are the back braces.

Here is a pic:

Attachment:
DSC00328r.jpg


Your spreaders should be constructed in such a manner to permit disassembly with one hand through the sound hole. This also means that the individual fitted blocks need to be able to pass though the sound hole too.

Here is another pic for you:

Attachment:
DSC01135.jpg


And pardon the flakiness here but I am all geeked out because I just got a picture of a golden eagle in my back yard.... :D

Attachment:
DSCN2889.jpg
Author:  Hesh [ Sun Jul 20, 2008 12:21 pm ]
Post subject:  Re: Putting the back on
If you don't have a go-bar deck here is a neat way to clamp on the back joint reinforcement requiring only a radiused stick and two clamps. With this cat skinner it's easy to clean up the squeeze-out from both sides of the strip.
Attachment:
DSC00322r.jpg


Here is a link to the toot explaining how to do this: http://luthiersforum.3element.com/forum/forum_posts.asp?TID=11167%20&KW=tutorial#forumTop%22
Author:  SkyHigh [ Sun Jul 20, 2008 12:24 pm ]
Post subject:  Re: Putting the back on
I guess I just realized of another mistake on my first guitar. I already installed the braces on the back...yes with out the back inforcements. gaah

I will just have to cut the reinforcement in the pieces and glue them on.
Author:  Hesh [ Sun Jul 20, 2008 12:28 pm ]
Post subject:  Re: Putting the back on
Sure no problem on this one - lots of folks install the back joint reinforcement in segments carefully fitting them between the existing braces.

I like to install mine first, the BJR that is, so that I can plane the profile of the BJR into a nice curved shape but there are lots of ways to do this.
Author:  James Orr [ Sun Jul 20, 2008 4:10 pm ]
Post subject:  Re: Putting the back on
Hesh wrote:
I like to install mine first, the BJR that is, so that I can plane the profile of the BJR into a nice curved shape but there are lots of ways to do this.


This is something I've had trouble with. Hesh, what kind of plane are you using to shape the profile?
Author:  James Orr [ Sun Jul 20, 2008 4:38 pm ]
Post subject:  Re: Putting the back on
Thanks, Todd.
Author:  Hesh [ Mon Jul 21, 2008 6:02 am ]
Post subject:  Re: Putting the back on
James my friend I use 3 planes to shape the back strip, the LN model makers plane (or the green one from LMI) and a 12 and 18mm finger plane. Blue tape next to the strip works fine to protect the back from the plane edges and I use a low tack version so as to not lift fibers when removing.
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