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I'm ready to glue bridges on a couple of guitars ...however, I've always been able to just place them on the guitar top, and they've fit fine...these two don't...the wings are almost 1/16" above the top surface. So, do I need to concave the bridge bottom (what's the best way?), or just rely on clamping to get the wings glued down. I have a vacuum clamp and the LMI bridge clamp. I think the LMI will do it, but I just want to make sure that's okay to do.

Thanks,
Larry

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http://www.presnallguitars.com

Some people don't shape the bottom of the bridge but just clamp it down. I have a 4x4 about 2 feet long with my 25 ft radius on one side and covered with a sanding belt. Just a few passes across that and the bridge fits just right. I made a handle that has pins to engage the string pin holes to make the job easier.

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Tickle your guitar daily, and it'll tickle you back.

John,
Whew! I thought you were going to say you used that 4x4 as a clamping caul! I will probably dry clamp it to see how it looks and shape the bottom if I have to. Thanks!

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http://www.presnallguitars.com

My teacher told me as long as it is good and flat, and you glue and clamp it properly, it shouldn't matter. but I always tape a square of sand paper centered on the bridge place of the guitar it is going to be glued to and sand it flush to that couture. You need to do this before prepping the top for gluing the bridge. It doesn’t seem to take too long and it makes a difference in the seating of the bridge.

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Wade
Nashua, NH
http://www.wadefx.com

I use a chain saw to rough out a curve on the bottom. That usually gets it close enough.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Ok, the truth is I sand a radius into the bottom of the bridge, starting with a file and eventually to scraper and sandpaper. Eventually I'm going to do what John How does (How does John?) and make a convex form from my sanding dish. I've also thought of a couple different ways, but this seems the easiest. Don Williams38513.765775463

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

making the bridge bottom contour match the top is just one more step in removing stresses which inhibit the top from performing its function. and it also means that the bridge has less stress trying to make it come off.

i can't think of, nor have i ever heard anyone argue positively against doing it.

I made a domed sanding disc by using bondo and molding it to the raidus dish I use for my tops.

I then cut it into a circle and mounted it to a small faceplate and use it on my lathe.

I made a holding device to hold the bridge to it while I sand the raidus to the bottom of the bridge.
Takes about 30 seconds to sand it.
Gary

I do mine the same way John does. I just like for things to fit without having to force them with clamps. Seems as if it should be better that way. I have no data to back that up though.

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Dave Rector
Rector Guitars

[QUOTE=Don Williams] I use a chain saw to rough out a curve on the bottom. That usually gets it close enough.[/QUOTE]
Chain saws are old fashoned. You should try Semtex or C4 if your supplier looks the other way on the paper work.

c4 and semtex are old tech. tres crude!

go for the moderne technique witn mini shaped cutting charges with sequential detonation!

I would have to say that if you try to force the wings down you are asking for trouble. I just took a piece of MDF (maybe 3" x 12") and ground it to a 25" raduis on my dish. then put PSA sandpaper on that, chuck it in my vise and back-and-forth it 'till all my witness lines are gone. It takes me longer than 30 seconds but it's very much worth it.

[QUOTE=crazymanmichael] c4 and semtex are old tech. tres crude!

go for the moderne technique witn mini shaped cutting charges with sequential detonation![/QUOTE]

GROUP BUY! GROUP BUY!

I used the last of my C4 on my mother-in-law's head cold...(what, she was a little congested ), so I guess I'll do the MDF grinding that Paul speaks of...one day I'm going to motorize my sanding dishes and all my problems will be solved! (I know, I know!)

Thanks guys!

Larry

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http://www.presnallguitars.com

[QUOTE=L. Presnall] I used the last of my C4 on my mother-in-law's head cold...(what?! she was a little congested...) [/QUOTE]

ROFLMBO
Don Williams38513.7691898148

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

hope wife has sense of humor!!!

By the by Paul, I just got in from the shop making the MDF thingie, and sanding the bridge bottom...perfect! Thanks for the info...10 minutes to make the caul, and 10 to sand!

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http://www.presnallguitars.com

Michael, my wife doesn't read this forum!

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http://www.presnallguitars.com

ain't you lucky!!!

Visualizing (as a woodworker, not yet as a luthier) even a very wide bridge, it seems to me that going to the trouble of creating a convex dome for sanding would be overkill. I would think a 2-D convex curved surface (as per John How), and sanding along the length of the bridge, would be more than adequate. I guess I become more and more wrong as the bridge becomes wider and wider (Kasha-esque.)

I'm saving my supply of C-4 for soundboard voicing.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I use my motorized sanding dish sander. I made a convex form by lining my concave dish with wax paper, mixed up some Bondo and put it on the wax paper. Roughed up a piece of 1" plywood with 36 grit on a grinder and then pressed the plywood into the Bondo. Allowed it to cure, cut it in a 14" circle, covered it with 100 grit PSA and chucked it on my dish sander.

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tim...
http://www.mcknightguitars.com

I did what Paul did, minus the motorization. You've got a radiused dish with sandpaper (one assumes), you've probably got some scrap MDF, so make yerself a 'positive' arched/radiussed surface to sand the top contour onto the bottom of the bridge. Honestly, I think making an MDF 3-d arched surface is faster than any 2-d arch ever. MDF sands very, very quicly, and there's not a whole lot of material to remove to reach 25' or 28' or whatever other radius is in use. Quick and painless, and you get a nice tight fit.

Mattia, 'zactly what I did, per Paul's suggestion...worked great, and so easy that anything else would take longer to build than all 7 bridges are worth, time-wise!

Larry

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http://www.presnallguitars.com

I keep trying to think of some fancy way to do this. Motorized, all jigged up, etc. But alas I grab my stick of MDF and spend a few minutes of sanding. Sometimes less is more.
Larry, glad it worked for you. BTW patent pending on that design. :^)

[QUOTE=crazymanmichael] making the bridge bottom contour match the top is just one more step in removing stresses which inhibit the top from performing its function. and it also means that the bridge has less stress trying to make it come off.

i can't think of, nor have i ever heard anyone argue positively against doing it.[/QUOTE]


YEAH!!