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  #1  
Old 05-10-2017, 03:17 PM
Albert D Albert D is offline
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Default Radius bridge to soundboard mating surface

I am working my guitar that I started with my luthier friend who moved away 5 years ago with all his tools. I need to fit the bridge to the soundboard and don't have the radius fixture available to me. Is there any reason I can't put a sheet of sandpaper on my top in the area of the bridge and sand it in place? I could maybe put a paper towel under the sandpaper for extra protection. I'm probably 3 or 4 weeks away from this stage but want to plan ahead.

Thanks for any input.
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Old 05-10-2017, 03:24 PM
ricklt ricklt is offline
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I have seen you tube videos​, where that's what they did. I think that is the only way to get it to match.

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Old 05-10-2017, 03:31 PM
Sam VanLaningham Sam VanLaningham is offline
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When my radiused block wasn't getting me a good fit, I put blue tape down on guitar for protection and did as you say, moving bridge back and forth on sandpaper. Worked Aok!


Sam
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Old 05-10-2017, 03:36 PM
dekutree64 dekutree64 is offline
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That's what I do. Sanding usually doesn't get it quite perfect, but close enough that it doesn't take long to get there with some careful scraping. Use the coarsest sandpaper you can find.
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Old 05-10-2017, 04:27 PM
Halcyon/Tinker Halcyon/Tinker is offline
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Cover the area well with low tack painters tape, then use a sheet of 100 grit stuck on with double sided tape. Don't press too too hard.
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Old 05-10-2017, 04:31 PM
Albert D Albert D is offline
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Thanks all for the help. Sounds like it should work just fine. Using the low tack tape for protection is a great idea. I hadn't thought of that.
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Old 05-10-2017, 05:32 PM
murrmac123 murrmac123 is offline
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My impression is that most experienced builders don't bother radiusing the underside of the bridge ... they leave the bridge flat and just clamp it with a flat caul underneath the bridgeplate.
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Old 05-10-2017, 06:28 PM
Halcyon/Tinker Halcyon/Tinker is offline
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I've done both ways.

I think it depends a lot on how much you radius your top. These days, I radius the bottom of the bridge and use a radiused caul on a the inside that matches the top radius.
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Old 05-10-2017, 08:15 PM
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nacluth nacluth is offline
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Yep, that's how we do it. Works fine.
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  #10  
Old 05-11-2017, 07:30 AM
redir redir is offline
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I just glue it flat too. I've never used a radius that is so dramatic that it can't be glued flat. Sometimes repairs require it though as the tops have bellied considerably.

But yeah that sandpaper method is an old trick, especially for arch tops. It's nice to do the bulk of the work with a scraper. It's also a good idea to finish off the sanding marks with a scraper too.
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