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Dumb questions about Brace Shaping
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Author:  Jimson [ Thu May 25, 2006 2:07 pm ]
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I am sitting here looking at an OM top that is ready for brace shaping - I am a trifle nervous about it.
Am I the only one who has put an accidental gouge in a top when shaping the braces?
Why do most folks seem to shape the braces AFTER affixing them to the top or back?
And why use a chisel? Why not use a moto-tool with a sanding drum attachement? A small plane looks great for final voicing but don't ya pretty much know the general shape (and radius) before you start bracing? I am wishing I had band-sawed the braces to the basic scalloped shape I assume I will wind-up with.
Finally, classical and steel-string BACKS seem over-braced to me - what am I missing?

I would appreciate your experiences, thoughts and opinions on this subject.

TFL.
Author:  Alain Desforges [ Thu May 25, 2006 2:21 pm ]
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Milt, you'd probably be the first NOT to have gouged a top. Now I use scrapers in strategic places to avoid the problem...

   I think the chisel is the tool of choice because of speed and control. With a bit of practice, a really well sharpened chisel is hard to beat.

   I know personally that I like to shape after since I don't need all sorts of different shaped cauls to hold my braces down while gluing. If they were pre-shaped, I'd have a hard time in the go-bar deck. If I had a small army of deep-throated cam-clamps, then maybe I'd try pre-shapping. Stew-Mac sells some pre-shaped scalloped braces, by the way.

   I've found small planes to be very handy as well. They can take a lot of stock off in a short order of time if you're not careful.

   Hope this helps.

Author:  Jim Watts [ Thu May 25, 2006 4:13 pm ]
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I use vacuum to clamp my braces on and pre-shape them to a rough shape ahead of time. I've got a top in the vacuum frame right now, yea! Pre-shaping helps but I still have to do the final shape. I would think you could do this with a go-bar deck but then again, I've never used a go-bar deck. Jim_W38863.0515509259
Author:  Serge Poirier [ Thu May 25, 2006 4:22 pm ]
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It happens to everybody Milt, the chiseling of the braces is one of my favorite part of the build, that is where i truly feel like an artisan. Practice on scrap to get the feel of it!

Serge
Author:  RCoates [ Thu May 25, 2006 5:58 pm ]
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On steel stringed guitars I have used a Dremel and sanding drum to shape the scalloped portions. That only goes so far then you have to clean em up with a chisel. I also use a small plane to get the basic shape.

It's really not that bad... the chisel that is. just make sure it's sharp and go slow.
Author:  Mattia Valente [ Thu May 25, 2006 7:33 pm ]
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I really like using chisels. Yes, there is the potential for slip-ups, but they're very effective, controllable tools. And I like my planes as well.
Author:  Colin S [ Thu May 25, 2006 7:42 pm ]
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If your worried about digging into the top just tape some art card next to the brace your shaping and then if the chisel slips you'll only dig the card.

I tend now only to "parabolic" my braces so I have been known to put the primary curve on the length of the brace prior to gluing. I don't bother now as once you get stuck in to shaping a brace with chisel and finger planes it is quite fast work. I also find that the bars in the go-bar sit more secuely on flat stock.

It's very therapeutic to start with a plain rectangular bit of wood and end up, after a few minutes paring, with all those sexy curves.

Colin
Author:  Jim Kirby [ Thu May 25, 2006 9:35 pm ]
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You could put down a few layers of masking tape either side of the brace if you are really worried about slips.

Personally, I find the process of brace shaping to be the most rewarding part of the entire process. I just use a finger plane (LMI Schneider) and curved chisel and go at it. It makes the outside world go away better than any other part of the process for me.
Author:  Serge Poirier [ Thu May 25, 2006 10:04 pm ]
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and when you see all those chips on your bench, you'll forget everything else!
Author:  Pwoolson [ Thu May 25, 2006 10:28 pm ]
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What Todd said! I hold one hand on the handle and put the other hand on the blade itself. Resting the sole of my lower hand on the brace, I sort of use back pressure to prevent any slips. If your chisel is sharp, this should be an easy, enjoyable task. If not, make them sharp!
You really should learn how to do it with chisels as that's really the "right" way to do it (if you aren't preshaping). Short cuts will only come back and bite you in the long run.
Author:  Sylvan [ Fri May 26, 2006 12:23 am ]
Post subject: 
It really helps, in shaping braces with a chisel, if you flip the chisel over
bevel side down and use it much like a plane. If you are careful the chisel
literally cannot gouge the top and you have much better control over the
work.Sylvan38863.3941666667
Author:  Bill Greene [ Fri May 26, 2006 1:11 am ]
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[QUOTE=Sylvan] It really helps, in shaping braces with a chisel, if you flip the chisel over
bevel side down and use it much like a plane. If you are careful the chisel
literally cannot gouge the top and you have much better control over the
work.[/QUOTE]

Well I'll be darned...I thought I'd come up with some new. Rats.    
Author:  Michael McBroom [ Fri May 26, 2006 2:00 am ]
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These are the only tools I use for shaping braces:



Well, I'll hit the braces with sandpaper when I'm done. If you look closely, you'll see some nicks in a couple of braces in the background. I'll soften them up when I sand.

I use the small plane (one of Mark's) for the initial shaping, to establish the cross-sectional contour. Then I use both the larger plane and the chisel for establishing the parabolic contour. I prefer the plane for the long braces; it's easier to keep a level line than with a chisel over the long runs of those braces. I like using the chisel for establishing the parabolic contour with the shorter braces, just because it's fast. After that step, I go back with the little plane and finish up the cross sectional contour, bringing the angled sides of the brace together to fine edges at their peaks. Sanding will blunt the edges a bit, which is fine.

Best,

MichaelMichael McBroom38863.4601273148
Author:  Jimson [ Fri May 26, 2006 2:46 am ]
Post subject: 
Good stuff - Thanks much!

I didn't think those little finger planes were used for establising the shape. If they work that well maybe I will try one.

Author:  letseatpaste [ Fri May 26, 2006 3:24 am ]
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Profiling braces with a finger plane is one of my favorite parts of guitar building so far... Scalloping braces with a chisel is one of my least favorite. It's actually not so bad, the more you do you'll find it gets less frustrating. It especially got less frustrating when I started keeping my leather honing stick thing and some honing compound within reach.

I use a curved block with sandpaper to bring it to final shape after I butcher it with the chisel. As I get better with the chisel, the less I need the sandpaper.
Author:  MSpencer [ Fri May 26, 2006 2:34 pm ]
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I have used masking tape on the sides of each brace and taped poster board as above as well. I roughly pre-shape most of my braces prior to glueing up on the GoBar deck. I then finish with a finger plane and sharp chisel.

Mike
White Oak, Texas
Author:  Lars Rasmussen [ Fri May 26, 2006 7:12 pm ]
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Another safe-thing you can do, is to put one or two thin strips of bindingtape around the corner of the chisel edge. use a wide chisel (like 1") and with the hand holding the blade, force the edge to cut from side to side like a knife. This ads a lot of control when you get used to the technique. And make shure your chisel is very very sharp, with a dull one you are more certain to get slips and bad cuts... this is for carving the scallops and ends, to give the brace the profile i use finger plane and in some tight spost a chisel, but im shure there are a million ways to do this...

Just work slowly, and if it gets a little rough, a soft little sanding block is very handy.

Good luck!Lars Rasmussen38864.1780902778
Author:  Alan Carruth [ Sat May 27, 2006 11:23 am ]
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Like many people, I shape the braces after gluing them down because it's part of the final 'tuning' process. You have to find out, by whatever means, how the braces and the top are working together, and shape them to get things working 'right', whatever that is. :)

I use small violin makers planes a lot, and chisles hardly at all.

I agree that most backs are too heavily braced. you can 'tune' them, too, and it can make a difference in the way the guitar sounds.
Author:  rich altieri [ Sat May 27, 2006 1:00 pm ]
Post subject: 
This might almost be like cheating but I picked up this electric chisel/carver at a garage sale and it gives me unbelievable control.

Author:  Martin Turner [ Sat May 27, 2006 10:14 pm ]
Post subject: 
[QUOTE=MSpencer] I have used masking tape on the sides of each brace
and taped poster board as above as well. I roughly pre-shape most of my
braces prior to glueing up on the GoBar deck. I then finish with a finger
plane and sharp chisel.

Mike
White Oak, Texas[/QUOTE]

This is basically the way I shape braces although I dont pre shape them.
Most of the shaping is done with paring chisels and finger planes. Final
shaping is done with sand paper. The key to using chisels for shaping
braces is making sure the chisel is sharp and being aware of grain
direction.
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