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| brace curvature-AM I CRAZY http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=1190 |
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| Author: | bob J [ Tue Mar 01, 2005 12:07 am ] |
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Iv'e seen the Go-Bat system and curved cauls used during the attachment of curved bracing. It seems to me the same result can be obtained by gluing curved braces to flat back or or soundwood with uncurved caul and heavy clamping. The braces, when clamps are released will return to their origional shape and bring the back and soundboard with them. Am I crazy, stupid or inexperienced? 
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| Author: | LanceK [ Tue Mar 01, 2005 12:17 am ] |
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Thats done all the time. Not a problem. |
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| Author: | Michael Dale Payne [ Tue Mar 01, 2005 1:20 am ] |
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Bob, before I built bowls I used a 24x24 piece of med firm closed cell foam under my tops and backs on the go-bar deck and allowed the brace curve to form the plate. It worked well. Like many, on my first I just shimed the edges with cardboard |
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| Author: | Colin S [ Tue Mar 01, 2005 1:30 am ] |
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Bob, As long as you ensure that the back is curved to the shape of the braces not the brace straightened to the shape of the back while the glue is drying, it's not a problem. I believe that a weakened glue joint could arise if they dry straight and then try and curve. Obviously more critical on back than front. Have a look at the Stew Mac instructions for their kit they show how to do this, though I believe they use shaped cauls on the back for the above reason. Their free kit instructions (and a lot of their other intstructions) are a useful simple guide to building. Stew Mac Kit instructions Colin PS I always glue mine on bowls on a Go-bar deck it's pretty foolproof. |
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| Author: | Dickey [ Tue Mar 01, 2005 1:42 am ] |
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I did my first as per kit instructions, gluing curved braces to a flat top. But after thinking it through, I made a guitar shaped jig for the ladder braced back, curved corresponding splines and glued to the jig. Then I proceeded to glue curved braces to the back, but in a curvature on the jig. So, even though it is done, gluing without stress may be better for the guitar? I use dishes now and am very happy with the results. Dave M. used to make them for a bunch of us. Dave are you still doing that? And by the way, did you ever get that sander you were going for? |
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| Author: | Mattia Valente [ Tue Mar 01, 2005 3:34 am ] |
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Making dishes is easy, buying them even easier, and a go-bar deck using just enough pressure works just fine. So I'll stick by it. |
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| Author: | bob J [ Tue Mar 01, 2005 9:34 am ] |
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Thanks to all. doesn't bending using cauls and go bars Put the same stress on the back as flat method when the back takes the shape of braces? |
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| Author: | Mattia Valente [ Tue Mar 01, 2005 7:13 pm ] |
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If you force the brace flat, that takes more force than forcing the back into a dome. Different stresses, and, I feel, greater ones. You can push an unbraced top or back into a dish with your index finger, and not much pressure. Try flattening a single back brace the same way. Now multiply by 4. I think it puts extra strain on the glue joint this way, since the braces want to go one way (spring back) and the back would like to stay straight, and we're also talking about gluing dissimilar woods in cross-grain directions. So I'd rather avoid it. |
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