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| Redwood top and bracing? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=29948 |
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| Author: | Wes Paul [ Wed Nov 17, 2010 10:45 am ] |
| Post subject: | Redwood top and bracing? |
I have a curly redwood top thats not highly figured but has a wavy curl to it. The build is going to be the shape of an L-00. I understand redwood can be problematic structurally. I am wondering if anyone has had issues using redwood? Should I brace it with spruce? Bigger braces, thicker top? ect.. |
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| Author: | Tom West [ Wed Nov 17, 2010 11:03 am ] |
| Post subject: | Re: Redwood top and bracing? |
Wes: Redwood can be brittle and crack easly from a sharp blow. Once i had a redwood top cut to shape and accidently dropped it on the floor.It split in two on one side of the soundhole and was on the floor in two peices.Glued up very easy though. I have only used spruce braces. As far as thickness and brace size goes,you have to work that out depending on the stiffness of the redwood top. Have only done a couple of redwoods and have found it to be responsive and bright especially on the high end.By the way these two have stood up well and have no cracks. Redwood is also more stable than spruce. Good luck. Tom |
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| Author: | Laurent Brondel [ Wed Nov 17, 2010 1:17 pm ] |
| Post subject: | Re: Redwood top and bracing? |
What you see as figure is localised runout. It is besides the fact that redwood is generally brittle. Leave your top thicker. Redwood braces is a non sequitur: why use a material that is brittle and split prone for structural purposes, especially on an already compromised top? Sitka or red would be my choice, for any top on a steel string. |
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| Author: | Andy Zimmerman [ Wed Nov 17, 2010 2:45 pm ] |
| Post subject: | Re: Redwood top and bracing? |
Redwood is reasonably stiff in the longitudinal plane but is very brittle in the other direction. It can snap between the long fibers very easily. In my experience using redwood it does need to be a bit thicker to obtain the same degree of stiffness. (I am a Somogyi grad) Example data for stiffness compared to Lutz spruce. Granted it is only one example of RW and there are huge difference within a species, but the overall point is clear. redwood top 0.113 thickness - deflection 279 Lutz spruce 0.085- 0.092 thickness range to get the same degree of deflection. I do go to this degree of stiffness on my OM and L-OO models. Slightly stiffer for the OM So if 0.085 would be my top for Lutz for the L-OO that piece of RW for the same model will be thicknessed to 0.113 to achieve the same degree of stiffness. Make sense |
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| Author: | Alan Carruth [ Wed Nov 17, 2010 3:06 pm ] |
| Post subject: | Re: Redwood top and bracing? |
For all the softwoods I've tested the stiffness along the grain is proportional to the density in the same way. All of the redwood I've tested for tops has been fairly dense, and so fairly stiff along the grain at a given thickness. I have seen low density redwood, though. As always, you have to work to the piece, not the species. Redwood tends to have very low damping, even lower the red cedar in many cases. The famous 'Lucky Strike' log had long-grain damping as low as Brazilian rosewood, and I've gotten redwood at the lumber yard that was as good in that respect. |
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| Author: | JasonMoe [ Wed Nov 17, 2010 6:59 pm ] |
| Post subject: | Re: Redwood top and bracing? |
One thing I noticed about redwood is when doing the binding, not to take too much off at a time. Redwood seems to want to chip out easier than spruces. I usually take about 4 passes. |
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| Author: | Doug Powdrell [ Wed Nov 17, 2010 9:38 pm ] |
| Post subject: | Re: Redwood top and bracing? |
Wes- Issues using redwood? Well, really depends on the piece. As previously stated, is easy to break along the grain when straight grained...it's stiff across the grain and can snap with minimal hand pressure....figured is a bit different....it may be a bit looser across grain....need to adjust bracing according to cross grain stiffness.....can't comment on longitudinal stiffness. any pics?? Wavy grain 'implies' loose cross grain IMHO....adjust accordingly. |
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| Author: | jfmckenna [ Thu Nov 18, 2010 4:59 pm ] |
| Post subject: | Re: Redwood top and bracing? |
I have successfully built with curly Redwood but honestly I would never do it again unless it was used for a double top. I'm sort of hoping that this guitar never comes back for a re-top but the customer really wanted it so... |
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| Author: | GregG [ Thu Nov 18, 2010 7:23 pm ] |
| Post subject: | Re: Redwood top and bracing? |
I have found the redwood I've used to be up there with the best spruce I have relative to stiffness. Can be a bit more brittle, but a little care and it's really not a problem. |
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