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Using Fox Bridge Clamp to Glue New Bridge on an Acoustic Guitar

Now we come to The Main Event, The Big Moment, in which we glue the new bridge to the old guitar.  Funny how I've been thinking about this for some time, and it actually takes just a relatively few minutes to pull it off.

I've been most concerned about the thing playing in tune when I'm done.  Although it's been years, maybe a decade or more since I last played this guitar, I don't recall that it played out of tune.  So I have assumed all along that the bridge placement as was more or less correct as it originally was.

I did discover that it was actually angled inward on the bass side a bit - in other words it wasn't perfectly square in relationship to the end of the fretboard.  I am going to correct that.

So for the first of many times, I'm laying out and checking the scale length.  From the far (headstock) edge of the zero fret to the dead center of the saddle between the third and fourth strings, it's 25 5/8 inches.  I measured the old bridge a bunch of times when it was still on the guitar, and that's what I got.

I'm using a variant on what I now think of as the Sven method of laying out the bridge.  That would be Sven from Argapa Ukuleles.  His advice on intonating my Gretsch uku was spot on, so I'm borrowing his methodogy again.

Once again, I double check the scale length measurement.  Then I use a ruler to measure for the distance from the end of the fretboard to the bridge.  Of course, I have the old markings on the soundboard to work from as well.

Then I put a small strip of masking tape in front of the bridge to mark the "length" placement.

And then I carefully use a clamp to hold the bridge down to the top.  And I put more tape on the front and tape on the sides to locate the whole thing.  And once again, I triple check the scale length measurement.

Since I have a pin bridge, I'm going to use a cool clamp to hold the bridge down when I glue it.

I carefully drill two 3/16 of an inch holes through the top and bottom E string pin holes in the bridge.

Generally, you'd glue the bridge first, then drill, but I need two access holes for my clamp.  The clamp is also holding a caul underneath the bridge pad, so that drilling won't split the bridge pad (plate).

The one clamp wasn't super strong, so I also held the ends of the bridge down by hand to ensure the whole thing didn't shift when I drilled.  The drill is also taking a small shaving off the pin holes on the bridge itself.

Then I can spread glue on the bottom of the bridge and use the clamp to hold the whole enchilada (mmm enchilada...) down.

The clamp came from LMI.  It's a Fox bridge clamp - an aluminum plate with four screws.  The inner two bolt through the bridge pin holes and the outer two screw down to hold the ends of the bridge down to the guitar.  Very clever, and I found it worked perfectly.

I ran a caul between the outer screws and the bridge so as to not mark up the bridge.

A bit hard to see, but this is the inside of the guitar with the clamp on.  There are wing nuts that attach on the two center clamp screws.  A great idea, since you can spin them quickly to tighten up.

And with the thumbscrews on the top, you can torque down the whole clamp as needed.

Now we just let the glue set.


 
 
 
 

Post a Comment 1 comments:

  • Sven Nyström said...
    June 1, 2012 at 2:59 AM
    The 'Sven method'..! I feel very flattered. And I really admire your skillz in getting the old parts off. Gonna have to learn about hot hide glue I think.

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