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 Post subject: Bracing A Back (Pics)
PostPosted: Sat Feb 23, 2008 10:30 am 
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Old Growth Brazilian Rosewood
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I have been slowly getting back into building after recently finishing a guitar and thought that I would share my process for bracing a back. This is not a toot but simply a look over my shoulder as I brace the back of an OM.

As always there are a million ways to do most anything in guitar building and this is simply my process for now.

And as always be safe, wear a dust mask, ear protection and use any and all of the best practices for working in a shop with edge and power tools.

This guitar is named Charo since it sports some beautiful Cuban Mahogany from Uncle Bob at RC Tonewoods. It was name it Charo or Fidel and since the wood is so pretty I didn't want to imagine it wearing a jogging suit....... :D

In addition, I have so very many pictures to post here I am going to have to use a number of posts in this thread throughout the day today. So friends your patience is greatly appreciated and always your comments are whole heartedly solicited.

Let's get started.......

Once the back halves are joined and thicknessed (this one is currently .089) I install the back strip reinforcement. More on this in a minute.

Then I make my braces in preparation of gluing them onto the back. The radius that I use for backs is 15' and I trace this radius on my bracing stock (this bracing stock is Adi) and then rough in the radius on a belt sander. The final radius is achieved by sanding in the proper radius dish, again 15'.

I have found that taping two braces together greatly reduces any errors in the final radius caused from the brace stock flexing while dish sanding. It also makes it much easier, for me at least, to hold onto while sanding in the dish.

Attachment:
DSC01149.jpg


When I am ready to sand the braces in the dish I make pencil marks that will be sanded away once the brace is hitting the dish in all areas.

Attachment:
DSC01151.jpg


Attachment:
DSC01152.jpg


I find that wearing a latex glove makes it much easier to hold onto braces while dish sanding.

Attachment:
DSC01155.jpg


Next I sand both sides of the taped together braces in the dish until the marks are gone.

Attachment:
DSC01154.jpg


And then the tape is removed and I have two radiused braces.

Attachment:
DSC01156.jpg


Attachment:
DSC01157.jpg


Attachment:
DSC01158.jpg


To be continued......... :)


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PostPosted: Sat Feb 23, 2008 10:41 am 
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Koa
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To momentarily butt in... nice tip on taping them together! I have 80 grit in my sanding bowls and the braces can be a real pain to control.

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PostPosted: Sat Feb 23, 2008 10:49 am 
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Old Growth Brazilian Rosewood
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Next the process is repeated for the rest of the braces beginning with rough profiling on the belt sander.

Attachment:
DSC01159.jpg


Attachment:
DSC01160.jpg


Attachment:
DSC01161.jpg


Now all my back braces are radiused to 15'.

Attachment:
DSC01162.jpg


Moving on to the back.

I am probably in the minority of builders who prefer to install the back joint reinforcement as one continuous piece. I do mark up the back prior including the places where the back joint reinforcement (BJR) will intersect a brace. When I glue down the BJR I don't spread any glue in the areas where the BJR will intersect a brace. This way when I remove pieces of the BJR from under where a brace will go the material being removed nicely pops up cleanly with a chisel.

For me the real benefit on installing the BJR as one piece is that I can then use planes to taper the edges to a nice tapered shape.

This BJR is Western Red Cedar simply because I like the color match with Cuban Mahogany.

Attachment:
DSC01163.jpg


Attachment:
DSC01164.jpg


Attachment:
DSC01165.jpg


To be continued...........


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PostPosted: Sat Feb 23, 2008 10:52 am 
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Brazilian Rosewood
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What colour are you painting this one Hesh?

Shane (trying to hide!) :lol:

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PostPosted: Sat Feb 23, 2008 11:09 am 
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Old Growth Brazilian Rosewood
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Not shown is how I cut the BJR for each brace.

I position the brace in it's respective position on the back (see the outboard marks on the back) and then use a single edged razor blade pressed against the brace to cut through the BJR. I am careful to be sure that the razor blade is firmly against the brace and that the brace does not move. Sorry I should have taken a photo of this........

Once the BJR is cut away for each brace I trial fit the braces prior to gluing them in place with HHG.

Attachment:
DSC01167.jpg


I try to have my HHG heating up well in advance of using it so that the HHG inside the bottle is the same temperature as the water in the Rival Hot Pot. Here we see that Hesh messed up and let his HHG get over 145 degrees F which is the maximum temperature that I will heat HHG to. Put this on in my blooper file...... :D

Attachment:
DSC01168.jpg


Using HHG is easy and fun just be sure to do a trial/dry run first and pre-position everything that you will use for easy access. My goal is to have each brace completely clamped with go-bars with in 15 seconds of laying down a bead of HHG.

Attachment:
DSC01170.jpg


I like to place small pieces of waxed paper under where the brace ends will extend over the top to avoid getting HHG on my sanding dish. Also notice that the braces will be glued to the back in the radius dish - since most of us have two or more dishes be sure to use the correct dish.........

Attachment:
DSC01171.jpg


And now the fun begins. My apologies for not showing the details of using HHG - there simply is no time to take pictures once the bead is down. Notice the squeeze out?

Attachment:
DSC01172.jpg


I typically will only do two braces at one time so that approximately 5 to 8 minutes later I can easily clean up the squeeze out before it jells to much.

To be continued.......

Attachment:
DSC01173.jpg


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PostPosted: Sat Feb 23, 2008 11:31 am 
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Old Growth Brazilian Rosewood
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Please everyone feel very free to weigh-in at any point. The goal here is to have a working thread that someone may benefit from and your input is greatly appreciated.

Shane my friend you guessed it - she will have a gloss black top....... :o :D

HHG cleans up very easily and in my humble opinion easier then Titebond or Fish Glue. If you wait 5-8 minutes most of the squeeze out will cleanly come up with some form of a squeegee. I use my engineers scale to squeegee up the excess HHG and hot water from the pot and paper towel if I waited to long and it jells to much.

Attachment:
DSC01175.jpg


The excess HHG becomes rubbery after waiting a bit and is easy to remove and use to gross out your family.

Attachment:
DSC01176.jpg


I clean up one side of the back first and then rotate my go-bar deck and repeat the clean-up on the other side. This takes very little time to do.

Attachment:
DSC01177.jpg


Attachment:
DSC01178.jpg


If I do take to long to clean up the squeeze-out hot water and paper towel works very well.

Attachment:
DSC01180.jpg


Next I glue the remaining braces in place and repeat the clean-up routine.

Attachment:
DSC01181.jpg


Attachment:
DSC01182.jpg


When all the braces are glued to the back and the squeeze-out has been cleaned up I leave the back clamped with the go-bars in the go-bar deck for at least 4 hours.

To be continued.......


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PostPosted: Sat Feb 23, 2008 11:45 am 
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Brazilian Rosewood
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Doesn't sanding your braces that way cause them to cant one way to the other? :shock: [headinwall] [xx(]

:D :lol: :lol: :lol: :lol: :lol: :lol: :lol:

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PostPosted: Sat Feb 23, 2008 11:54 am 
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Welcome back! :D

I am sorry to be a safety nag here but I wanted to mention to be sure to unplug your Hot Pot when you are done with your HHG session. Thanks.

I will typically mix up a batch of HHG in a 4 ounce bottle and transfer a working quantity to a 2 ounce bottle. I store the HHG in the fridge when not in use and will keep a batch for 4-5 weeks. I have reheated a single batch 5 times with no problems.

Once the glue has dried I carve my braces. I tend to do the vast majority of my brace shaping, carving with small finger planes. I will use a chisel for the ends.

For this top I am using two low, inefficient and fairly massive braces for the lower bout. This is a shape that I have seen in David Collin's shop that was used on 1930's Gibsons and I have been using this shape for a while now with good results. For the upper bout I like parabolic brace shapes and profiled in the shape of taller, thin triangles - a very efficient and less massive shape.

Of course what shapes that you use is completely up to you.

When I am using my finger planes to profile my braces I place small pieces of mylar down over the back strip and tape them in place with low tack tape. This protects the BJR from the hard edges of the finger planes and works quite well.

Attachment:
DSC01243.jpg


Here are some shots of the brace shaping.

Attachment:
DSC01244.jpg


Attachment:
DSC01245.jpg


Attachment:
DSC01246.jpg


And here, after some clean-up and final sanding is my completed back. My last step is to glue on my label which will also have a protective piece of plastic taped over it (not shown) prior to gluing the back to the rim.

Attachment:
DSC01308.jpg


Attachment:
DSC01309.jpg


Attachment:
DSC01311.jpg


Many thanks folks! :)


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PostPosted: Sat Feb 23, 2008 11:56 am 
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Are you using a premade back strip reinforcement? LMI? Is the color match an issue?


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PostPosted: Sat Feb 23, 2008 12:02 pm 
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Old Growth Brazilian Rosewood
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Zach buddy yes this back strip came from LMI.

The color match is an issue to me but I am sure it would not be an issue to everyone.

Billy my friend I wondered if anyone was going to bring that up...... :D Yes sanding your braces in the center of the dish and then installing them away from the center of the back/top will cause them to cant some. This is easily made up for by shaping them to stand up right. Or you can just sand them too in the respective location in the dish that they will live on a back/top...... But I did not want to get into that here........ :D

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PostPosted: Sat Feb 23, 2008 1:02 pm 
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Hesh--

Are you using Adi for your brace stock?

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PostPosted: Sat Feb 23, 2008 1:30 pm 
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Jim yes - Adi is all I have ever used so far.

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PostPosted: Sat Feb 23, 2008 2:11 pm 
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Hey... how much power does that light have and where did you get it? I need to find something like that for my deck.

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PostPosted: Sat Feb 23, 2008 2:22 pm 
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Brock buddy the light was purchased about 8 years ago as art lighting and was just laying around here. It says that it was made by Chuan Mo Corp. (China) and they were about $75 when I purchased them....... Kind of pricey.... It's 50-60 watts halogen, wall, ceiling, or table mount with a safety that has to be depressed for it to work. They were very nicely made though.

I just did a Google search on the maker and this company has gone to all LED lighting since. I have an extra one though that if you come to the gathering in a couple of weeks is yours. :)

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PostPosted: Sat Feb 23, 2008 3:00 pm 
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Nice documentation photos Hesh. Thanks for sharing.

Even your Sanding dust lines are in neat order. (I'm sure for easy cleanup).

I usually (I say usually, I've only done it onece), shape mine in the brace shaper Jig from Tracy at Luthier Suppliers and then Finish them off in the Sanding Dish by sanding them in their correct position in the dish.

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PostPosted: Sat Feb 23, 2008 11:22 pm 
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Nice Hesh.
When you squeeze out a bead of hhg for your BJR do you just lay the strip over it, or rub it a bit? Just wondering, if you do rub the joint would any glue get on the areas where your bracing would go. What is your method of clamping the reinforcement strip?
Marbles eh? that's interesting. I cut a piece of wire with 1/2" squares to hold the jar off the bottom of the hot pot. I've also been using a brush to apply the hhg, but I think the squeeze bottle would be faster.

Thanks for sharing

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PostPosted: Sun Feb 24, 2008 8:12 am 
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Blain my friend I have used Tracy's very fine brace shaper jig and it is indeed a nice jig.

Chuck buddy I glue my BJR with a special stick that is 1/2" wide and has a 25' radius on one side. All I have to do is clamp the two ends completely down and the radius on the stick applies pressure on the BJR over it's entire length.

Attachment:
DSCN2509.jpg


Attachment:
DSCN2510.jpg


I am still using Titebond original for gluing the BJR because it gives me time to be fairly neat in painting the glue onto the marked back and not in the intersections of the braces.


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PostPosted: Sun Feb 24, 2008 9:58 am 
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Hesh wrote:
I have been slowly getting back into building after recently finishing a guitar ...


The mind reels at the inconsistencies in that statement! :D :D :D

Thanks for the view. [:Y:] [:Y:] [:Y:]

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PostPosted: Sun Feb 24, 2008 10:55 am 
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Jim that was indeed a confusing statement - sorry..... :D What I should have said was that I took 2 weeks where I only "thought" about guitar building and did not engage in the physical act of guitar building....... :) :o

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PostPosted: Sun Feb 24, 2008 10:57 am 
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Nice work! Now show us how you glue it to the rim! :mrgreen:

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PostPosted: Sun Feb 24, 2008 12:07 pm 
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It's good to see you back in the shop Hesh! So you're doing another black top guitar eh ?
Great ! I hope it turns out as nice as the Tiger Myrtle L-00. What are you using for the top?
Adi I bet !! :D Thanks for the back brace pics !

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PostPosted: Sun Feb 24, 2008 12:10 pm 
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Black top? then it will definitely be Shane's Lutz !

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PostPosted: Sun Feb 24, 2008 12:50 pm 
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Thanks Hesh, just at the same point you are, just finished French Polishing a big 12 fret mahogany dreadnought (boy are my arms tired :D ) and now have to go cut out some back bracing from my Adirondack bracing stock. I do things much like
you do but learned a couple of tricks from your great tutorial. Thanks and good timing!
Best
Bruce

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PostPosted: Sun Feb 24, 2008 2:18 pm 
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Thanks Folks! :)

It will be a while before I glue the back to the rim since I have to build a top first........ But I did just join the top plates if that counts for something..... :lol:

Alex and Dave not Shane's beautiful Lutz on this one, poor Shane has suffered enough abuse at the whim of my color choices. This one will have a German top from Uncle Bob.

So Bruce do you feel like the Karate kids after french polishing a d*ead? :D

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PostPosted: Sun Feb 24, 2008 6:28 pm 
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Hesh wrote:
Blain my friend I have used Tracy's very fine brace shaper jig and it is indeed a nice jig.

Chuck buddy I glue my BJR with a special stick that is 1/2" wide and has a 25' radius on one side. All I have to do is clamp the two ends completely down and the radius on the stick applies pressure on the BJR over it's entire length.

Attachment:
DSCN2509.jpg




Hesh, is that a typo or part of your secret to success? You are using a 25' radius gluing caul on a back with a 15' radius.

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