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 Celebrity CC54i iDea dissassembly
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arumako |
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Joined: October 2012 Posts: 1018 Location: Yokohama, Japan | Cavalier - 2016-02-05 2:51 PM Carbon fiber uni would use smaller braces and fewer for the same strength for sure. I think you'd have to take into account that the new material could need a new pattern to take advantage of its properties. I think you're right Cavalier. Not one to give-up so easily, I've outlined a basic bracing pattern based on the Quintad bracing with 3 main bracing pieces (in orange) and 3 tone braces (in green).
The bracing surface area is 34% lower to "soften-up" the rigidity of the CFRP braces and bridge (may need to route under the bridge in strategic areas to relieve it from it's "hyper" rigidity as well). The braces will be much shorter and thinner too. T2, T3 & T4 (un-marked) will be no more than 3mm in height, 2mm wide at the base and tapered to 1mm at the top. B2 & T1 are designed to jump over the bridge area to make sure the extreme rigidity is not killing resonance. It's going to be difficult to bring out the bass response in the guitar, so I'm leaving the bass area as clear as possible. Bracing will be added if necessary in the areas shaded in red. Frankly, I have no idea how this will all sound, but the spruce top has a pretty sweet tap tone, and with some tweaking, I might be able to get this thing to sound half-way-decent. Even if it doesn't work out, I sure am learning a bunch! Great fun! Edited by arumako 2016-02-06 10:19 AM | ||
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| Cavalier |
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| DanSavage |
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Joined: June 2012 Posts: 2303 Location: Lake Forest, CA | arumako - 2016-02-05 8:55 PM White Pine = WP; Sitka Spruce = SS; Yellow Birch = YB; Carbon Fiber = CFRP ...and compared 6 physical characteristics of the material: Specific Gravity: WP - 0.35; SS - 0.40; YB - 0.62; CFRP - 1.5 Density (g/cubic cm): WP - 0.400; SS - 0.432; YB - 0.689; CFRP - 1.585 Compressive Strength (psi): WP - 4,800; SS - 5,610; YB - 8,170; CFRP - 15,954 Bending Strength (Gpa): WP - 0.0593; SS - 0.07; YB - 0.114; CFRP - 10 Stiffness Strength or MOE (Gpa): WP - 8.55; SS - 11.03; YB - 13.86; CFRP - 135 Specific Strength [Pa/density(kg/cubic meter)]: WP - 148,250 SS - 162,037 YB - 1,661,829 CFRP - 44,164,037 Since you're into model plane building, I'm sure you already know this stuff; but I think what this means is that CFRP is too strong. The material has excellent strength-to-weight (specific strength) characteristics, but it's just too stiff! I was thinking I could fabricate a bridge out of a piece of 3K Twill 70% CFRP block that I have 2"x7"x0.5"; but since a bridge is essentially a "brace", that will stiffen things up quite a bit. Combined with CFRP braces...maybe too stiff? I think the stiffness figures are for a given size. Yes, you're correct. I am familiar with CF. I think using CF for braces would work fine, but you would want to do one of two things. Either, use very thin CF laminated to the wood (top and/or bottom) or, if you use CF alone, use very thin pieces so that you get some flexibility to the top. If you google for carbon fiber guitar braces you'll see that there's a lot of people experimenting with CF. For testing, the first thing I would do is simple deflection testing. Take a piece of spruce that's the size of a brace and clamp one end to the work bench. Next, hang a weight off the free end and measure how much it deflects. Then, do the same thing with a piece of CF and use different thicknesses until you get the deflection you desire. I don't think there's anything inherently wrong with using CF for a bridge. Yes, it will be stiffer than wood, but if you want it to have the look of CF, but the flexibility of wood, just reduce the thickness until you get what you want. Even though CF is stiff, it will still bend. It's just stiffer than most other materials for a given size. What makes CF popular is that you can reduce the size which reduces the weight, but still retain the same stiffness. I'm sure if you use the same principle for your braces, your experiment will be successful. Carry on.  | ||
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| tpa |
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| arumako |
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Joined: October 2012 Posts: 1018 Location: Yokohama, Japan | |||
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| BanjoJ |
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Joined: September 2012 Posts: 809 Location: Thredbo, NSW, Australia | |||
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| BanjoJ |
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Joined: September 2012 Posts: 809 Location: Thredbo, NSW, Australia | I was interested to see the bracing in my ute. The braces vary in height along some braces, and the long braces are different to the short braces. (Braces-07S.JPG) (Braces-08S.JPG) (Braces-09S.JPG) Attachments ----------------  Braces-07S.JPG (60KB - 0 downloads) Braces-08S.JPG (61KB - 0 downloads) Braces-09S.JPG (65KB - 0 downloads) | ||
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| tpa |
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| arumako |
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Joined: October 2012 Posts: 1018 Location: Yokohama, Japan | Cavalier - 2016-02-05 2:51 PM ...Careful though, as I remember some of those honey tree efforts came to a sticky end. Hoping to avoid the sticky end, and there is still a long, long way to go, but materials are prepped and in order...
The CFRP bridge and braces are going to be especially challenging; but if I don't botch it up, the purfling and binding should work out pretty nicely. Maybe a fall 2016 completion. Gonna take it real slow... | ||
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