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Building an OLf SJ and need some advice.
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=29764		 Page 1 of 1
Author:  Larry Drover [ Wed Nov 03, 2010 5:31 pm ]
Post subject:  Building an OLf SJ and need some advice.
I am building the Olf Small Jumbo...This is my first one of this style...I love the shape of this guitar...I have followed the bracing sizes from the plans..5/16" for the X bracing and 1/4 For the tone bars...The top is .118 thick...The braces are scalloped and 3/4" high
I have a gut feeling that I am a little overbraced...I have installed the binding on the top and am seriously thinking about removing the back and carving the braces some more...I am not getting much of a tone from the top when tapped at the bridge plate area...although there was a little improvement when the top bindings were installed...
Will the sound improve noticably when I install the back bindings?
Should I follow my gut feeling and remove the back and do some more carving?
Should I go ahead, install the back bindings and see how it turns out?

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Author:  LaurieW [ Wed Nov 03, 2010 5:43 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
If you don't like how it turns out, you can always give it to a buddy :D

I bought the SJ mold too, so I better pay attention!

Laurie
Author:  Larry Drover [ Wed Nov 03, 2010 5:47 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Hey Laurie...Just got a bad feeling this one is not going to turn out the way I want it to.
Author:  Steve Saville [ Wed Nov 03, 2010 5:59 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
It looks way over-braced to me and the top is pretty thick.
What is the height of the braces at the x-brace?
Can you describe the tap tone when you tap at the bridge?
Author:  meddlingfool [ Wed Nov 03, 2010 6:03 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Obviously you can't tell for sure from pictures, but my gut reaction was that it's overbuilt as well. If you have the skills to remove the back and rework the braces I think you'd be doing yourself a favor. But that's just my two cents and I haven't built one of those so...
Author:  Steve Saville [ Wed Nov 03, 2010 6:13 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
meddlingfool wrote:
Obviously you can't tell for sure from pictures,...........


What kind of meddling fool are you? Come on! bliss bliss
Author:  Larry Drover [ Wed Nov 03, 2010 6:40 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Steve...3/4"at the X brace intersection...The tap at the bridge plate is a dull thud with very little sustain..The back seems to have more sustain when tapped..I would have no problem removing the back and do some work on the bracing and I think thats the way I should go...I think I read somewhere in one of the threads here, that some people who went by the plan found that it was not overbraced......To me ,I think I should have taken the braces down more...Thanks
Author:  Larry Drover [ Wed Nov 03, 2010 7:49 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Todd..I have built OM guitars and have used X bracing and tone bars with measurements similar to what you have posted...don't know why I put so heavy a bracing system on this one, other than its a new model for me and I was looking for a starting point for future SJ guitars...Here's what I plan on doing....Remove the back...No binding yet so no problem....Reduce the height on the 5/16" X bracing to 1/2" height...Take the 1/4" tone bars down to 1/2" height (scalloping both) and make the finger braces considerably smaller..With the top attached I should be able to tell the difference as I remove the extra wood...How do you feel about doing this?
Author:  alan stassforth [ Wed Nov 03, 2010 10:35 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
If it was mine, and I took the back off,
I would make the finger braces 1/4" tall,
make the x brace lower bout look like the upper bout,
and make those whatcha-callit braces in the lower bout about 3/8' thick.
Then again, I don't know what I'm doing either!
Author:  Barry Daniels [ Thu Nov 04, 2010 8:01 am ]
Post subject:  Re: Building an OLf SJ and need some advice.
And taper all the brace ends below the waist down to nothing.
Author:  Pat Foster [ Thu Nov 04, 2010 8:13 am ]
Post subject:  Re: Building an OLf SJ and need some advice.
Larry,

You could shave the braces through the soundhole to avoid having to remove the back, using height blocks to measure your progress. This was commonly done in the 70s when scalloping braces on Martin dreads. A small spokeshave with its ears removed makes a great tool for this. Working blind through the soundhole is a bit of a challenge at first, but it becomes easy pretty quick. The size of your forearm would be a factor though.

Pat
Author:  Alexandru Marian [ Thu Nov 04, 2010 8:16 am ]
Post subject:  Re: Building an OLf SJ and need some advice.
If you want to mimic the back binding, wrap the edge in one or two layers of sticky tape. It is not a matter of stiffness but air loss. A few small holes (you might not even see them) and the tap tone is completely ruined.

This being said, it does look way overbraced, not necessarily in the way of height and width, but in terms of "meat" on the sides of the braces. And the X is square for too far from the intersection.
Author:  Larry Drover [ Thu Nov 04, 2010 3:41 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Thanks to all of you who took the time to respond to this thread...You have been most helpful.
when the bracing was carved to the plan specs, It really looked like it was overbraced...The tap at the bridge plate was a dull thud...I installed the binding on the top but was hesitant to put them on the bottom...After getting good advice here, I went and removed the back this morning. I lowered the height of the X-brace from .750 to .600...The tone bars were lowered to .500 and the finger braces down to.300 high....As I was removing the wood I kept tapping the top ever so often...You could hear the sound really come into the top...The top now has a really good tap tone and a lot of sustain..The top is back on now. I will wait until tomorrow before I remove it from the clamp and see how it sounds...
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Author:  Gtrman13 [ Fri Nov 05, 2010 12:28 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Sounds like your tweaks have helped out! I've never built an SJ, so I can't comment on your numbers. Slightly off topic, but I noticed you don't have any side supports. Any reason for this? I know a lot of plans don't include anything about them, but they can still be a good idea to add some. Just wanted to throw that out there.
Author:  Larry Drover [ Fri Nov 05, 2010 3:09 pm ]
Post subject:  Re: Building an OLf SJ and need some advice.
Got the back back on and the binding finished...Tap tone is very nice and lots of sustain...A little advice can go a long ways sometimes.When Todd pointed out that there was only a few square inches in the difference in a Small Jumbo and an OM ,I knew I was over braced...Guess the word Jumbo gave me the impression that it was a larger guitar..Side braces...Well, first couple of guitars I used them, gave up after...No problems so far...Larry
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