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| Martin OM repair/rebuild - Concave top? http://www-.luthiersforum.com/forum/viewtopic.php?f=10101&t=44487 |
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| Author: | absrec [ Tue Nov 04, 2014 8:24 am ] |
| Post subject: | Martin OM repair/rebuild - Concave top? |
I have this OM on my bench at the moment. It was in a fire. The customer originally just wanted a neck installed. After inspection, I determined that it was going to need more than that. The back braces were all separated so I removed it and cleaned everything up and the braces and center strip are now being glued back onto it. So, I'm looking at the top and trying to determine it's radius. What I found is that it has just the opposite. The strange thing is that the braces are all solid. No gaps whatsoever. There is roughly .100" worth of concave dish to the top behind the bridge though. Seems like this is not right. |
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| Author: | meddlingfool [ Tue Nov 04, 2014 10:40 am ] |
| Post subject: | Re: Martin OM repair/rebuild - Concave top? |
I could see how a fire could permanently leave it concave through drying out. |
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| Author: | absrec [ Tue Nov 04, 2014 12:13 pm ] |
| Post subject: | Re: Martin OM repair/rebuild - Concave top? |
I know this is a really stupid question to ask but I'm going to ask it anyway. There's no way that Martin would have left the radius concave to compensate for the fact that the strings will pull it flat. Right? In other words, I'm assuming this is not a deliberate part of the design. My first inclination was to remove the braces and re-radius and basically rebuild the top. I just don't want to go through all of that only to find out that I screwed the thing up. Sent from my iPhone using Tapatalk |
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| Author: | arie [ Tue Nov 04, 2014 12:27 pm ] |
| Post subject: | Re: Martin OM repair/rebuild - Concave top? |
re-hydrate and see what that gets you first. |
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| Author: | John Arnold [ Tue Nov 04, 2014 12:31 pm ] |
| Post subject: | Re: Martin OM repair/rebuild - Concave top? |
No, a sunken top is not deliberate on Martin's part. Since drying out is the probable cause, you may try humidifying it. But IMHO, the only way to permanently change it is to re-brace the top. Martin generally uses a radius of about 50 feet on the tops, but in this case I would probably go with more curvature to counteract the shrinkage effect. About 25 or 30 foot would be my choice. IMHO, there should be no need to do the tone bars or finger braces....just the X-braces and upper transverse brace. Since the back is removed, I would do it with the top in place. I typically remove a section of kerfing at the bottom ends of the X-braces to notch the braces into the kerfing. The brace is installed by inserting it under the kerfing on the upper end. Then the kerfing section is reinstalled. Similarly, only one end of the transverse brace needs to be done this way. |
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| Author: | absrec [ Tue Nov 04, 2014 1:01 pm ] |
| Post subject: | Re: Martin OM repair/rebuild - Concave top? |
That makes sense Sent from my iPhone using Tapatalk |
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