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| Too thin on this redwood? http://luthiersforum.com/forum/viewtopic.php?f=10101&t=49100 |
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| Author: | MikeWaz [ Tue Mar 07, 2017 9:11 pm ] |
| Post subject: | Too thin on this redwood? |
One of my current builds is for a friend. By the time I got all the imperfections out of this redwood I was at .095-.10 in thickness. That seems really thin for an OM even if I brace it heavily, right? Could it be  safely put to use on a future parlor sized guitar? I hate to discard it because it's such a nice piece but will do so if that's the right thing.Sent from my iPhone using Tapatalk |
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| Author: | James Orr [ Tue Mar 07, 2017 9:20 pm ] |
| Post subject: | Re: Too thin on this redwood? |
I wish is could flex it. Redwood can be just as stiff as spruce. The redwood top on my current guitar is .085. If you don't sand it until it's time to prep for finish, my hunch is that it's OK. Sent from my iPhone using Tapatalk |
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| Author: | J De Rocher [ Tue Mar 07, 2017 9:24 pm ] |
| Post subject: | Re: Too thin on this redwood? |
I think it depends on how stiff it still is along the grain. How does its stiffness compare to the stiffness of other tops you've made that you were happy with? |
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| Author: | printer2 [ Tue Mar 07, 2017 10:17 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Maybe a 00? |
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| Author: | kencierp [ Tue Mar 07, 2017 10:18 pm ] |
| Post subject: | Re: Too thin on this redwood? |
I'd use it -- provided its not floppy length-wise, most of the redwood I've worked is very stiff in both directions. |
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| Author: | DennisK [ Tue Mar 07, 2017 10:51 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Certainly can be made to survive with proper bracing. The only question is whether you'll like how it sounds. As others have said, there's no way to know the stiffness just from the thickness. Especially with redwood. And you can't really do deflection testing when it's guitar shaped. So flex it with your hands and make your choice. |
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| Author: | truckjohn [ Wed Mar 08, 2017 7:01 am ] |
| Post subject: | Re: Too thin on this redwood? |
There's some redwood that's like cedar. Some redwood like spruce. Which is it? Next - just making a normal bracing scheme beefier to compensate for a thin top doesn't usually work out like you would think. The whole thing is a system. Think of it like your floor. If you use 2x12 oak planks for your floor - you can use huge oak beams about every 4 feet apart for floor joists. If you use 1/2" plywood - you better have joists every 12". If you consider this to be a soft, floppy top - consider a double X or some sort of lattice bracing. All that said - the current thickness is not outside the realm of "acceptable"... But the result is probably going to be a warmer sounding guitar. |
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| Author: | George L [ Wed Mar 08, 2017 10:53 am ] |
| Post subject: | Re: Too thin on this redwood? |
Is there a rosette face down in that photo? |
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| Author: | Alan Carruth [ Wed Mar 08, 2017 1:11 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Have you any idea about the density? Usually with softwoods the Young's modulus along the grain is proportional to the density. Some redwood, such as the 'LS' stick, is right up there in density and stiffness with Sitka and Red spruce. I can't thinl of when I've seen redwood that had density as low as most WRC. You should be able to test offcuts from that top, as well. It's not as good as testing the whole top, but better than nothing. Make rectangular strips and suspend them like xylophone bars from rubber bands or threads .21 of the length in from the ends of the strips. Tap in the middle, and record the sound. From there you can use various methods to find the pitch. With that, and the dimensions and mass of the strip you can calculate the Young's modulus, and use THAT to find the 'correct' thickness. The hardest part with those small strips is getting accurate thickness and mass readings. |
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| Author: | Mike Collins [ Wed Mar 08, 2017 3:06 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Use it. Just make your X braces (if that's what you using ) thin(6mm)wide & 14mm tall at the the joint. Taper them to the sides-NO thick brace at the side to top joint. Flex the top & determine the direction you want to go in from there. mike |
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| Author: | MikeWaz [ Wed Mar 08, 2017 7:00 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Thanks for all the responses! I'd try what Alan said but I already cut the scraps for soundhole reinforcement. I'm pretty sure I'll go ahead and build with it. I'm building it for a good friend. If it turns out to be a stinker, I'll build him another next year. Mike Collins wrote: Just make your X braces (if that's what you using ) thin(6mm)wide & 14mm tall at the the joint. Taper them to the sides-NO thick brace at the side to top joint. Flex the top & determine the direction you want to go in from there. mike Mike, I'm not sure I'm following you. Are you saying that I should used tapered instead of scalloped X braces? I typically don't inlet the long legs of the x-braces to the sides. Should I consider doing inletting them for added stiffness/structural integrity? |
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| Author: | Mike Collins [ Thu Mar 09, 2017 3:28 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Yes taper the braces to the sides. From a high @the center joint to 2mm height to be inlet to the linings. This 2mm height should be started at least 30mm from the linings. This will help keep the center of the top strong & stiff but the edges flexible. Sound & tone will be alive & well balanced . And as already said reinforce the rosette area on the inside of the top. Mike |
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| Author: | MikeWaz [ Thu Mar 09, 2017 4:03 pm ] |
| Post subject: | Re: Too thin on this redwood? |
Mike Collins wrote: Yes taper the braces to the sides. From a high @the center joint to 2mm height to be inlet to the linings. This 2mm height should be started at least 30mm from the linings. This will help keep the center of the top strong & stiff but the edges flexible. Sound & tone will be alive & well balanced . And as already said reinforce the rosette area on the inside of the top. Mike Thanks Mike! If nothing else this will be a learning experience. I'm building two other OMs in parallel - one red spruce and one Sitka. Sent from my iPhone using Tapatalk |
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