If you look on the bright side, most plans are over built anyway, so if you use the Englemann and stick to the plan, win win.
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| Brace material for steel string http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=49400 |
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| Author: | Imbler [ Thu May 25, 2017 7:30 am ] |
| Post subject: | Brace material for steel string |
I'm building my first steel string (normally build classicals), and I have a big stock of very nicely quartered Engelmann Spruce brace wood. The plans call for Sitka top bracing. If I used the Engelmann, how much would I need to increase the brace dimensions (if at all)? Since this is my first, I can't really brace by stiffness because I have nothing to compare to, Thanks for any help, Mike |
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| Author: | Mike Collins [ Thu May 25, 2017 7:39 am ] |
| Post subject: | Re: Brace material for steel string |
Use the wood you have. It may be more flexible! It may be lighter in weight ,which could help with loudness & tone. Mike |
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| Author: | truckjohn [ Thu May 25, 2017 9:00 am ] |
| Post subject: | Re: Brace material for steel string |
It depends on how stiff it is compared to average book values. Say average engleman has a modulus of elasticity that's 15% softer than average sitka... Since stiffness goes with the cube of beam depth - making up 15% stiffness only requires something like 5% more thickness... Say your top bracing sitka is 16mm - engleman would only need 0.8mm more depth to be back at the same stiffness.. |
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| Author: | Clay S. [ Thu May 25, 2017 10:05 am ] |
| Post subject: | Re: Brace material for steel string |
If you look at compare average values listed for the spruces, Engelmann has about 90% of the elastic strength of Sitka. If you have a large stock to choose from, you might do a simple test to find out which are the stiffer pieces and use them as you would Sitka. Most plans list brace sizes on the conservative side, so even a less stiff piece will usually work. |
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| Author: | ernie [ Thu May 25, 2017 10:52 am ] |
| Post subject: | Re: Brace material for steel string |
I would chose the sitka for a ss gtr..I spent many yrs in BC and englemann spruce comes in light, med , and hvy densities depending on where it/s grown on the west coast.. If your going to use e. spruce test it to see how stiff it is , and then factor the difference. and add that height to your bracing e.g. if the plans for sitka brace height is 12mm and your englemann brace is 25% weaker I would make my e. brace 15mm high. This is just an example, your experiments might dictate otherwise |
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| Author: | jfmckenna [ Thu May 25, 2017 1:32 pm ] |
| Post subject: | Re: Brace material for steel string |
If you look on the bright side, most plans are over built anyway, so if you use the Englemann and stick to the plan, win win.
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| Author: | John Arnold [ Thu May 25, 2017 3:11 pm ] |
| Post subject: | Re: Brace material for steel string |
Truckjohn is correct. Stiffness is proportional to the cube of the height. Adding 25% to the height will increase the stiffness by 95%. If you want to make the braces wider, then stiffness is directly proportional. In other words, if you want to increase the stiffness by 25%, increase the width by 25%. I built guitars all through the 1980's with Engelmann bracing, and I made the braces the same dimension as a stock Martin or Gibson, or very slightly taller (no more than 5%). Those guitars have survived just fine. |
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