Thursday, July 01, 2010

Gluing on a bridge

I’ve just glued the bridge onto the parlour guitar. This time, I didn’t video the process because I find this very final stage the most nerve-wracking of them all. You’re working with a variety of sharp tools on the freshly finished soundboard and need to concentrate 100%; months of hard work could be written off in the blink of an eye!

However, I know that there is a lot of interest, out there, in this particular stage, so I thought that I’d explain the process for you.

The first step is to cover the general area, where the bridge will go, with masking tape. I use a low tack tape designed for delicate surfaces; it is possible, if using very strong tape, to pull the finish (particularly water-based lacquers) clean off of the guitar! Don’t ask me how I know!

Next, some very careful marking out; I use a soft 7B pencil so that you don’t have to press too hard to make a mark. As I was marking out I counted that I needed 4 different types of ruler to measure with!

Once I’ve checked 27 times that the bridge is in the correct position, I scribe the outline with a scalpel (brand new blade!). You have to cut through the tape and lightly score the surface of the finish; once through the tape you can feel (under the blade) the different densities of winter and summer growth on the soundboard. A small piece of double sided tape locates the bridge nicely.

Remove the tape from the area under the bridge and scrape the finish away; you’ve got to get back down to the bare wood so that the glue bonds.

I use a chisel for this; I run a burnisher over the edge to form a burr so the chisel can then be used as a scraper.

With the surface of the soundboard clear of finish, the bridge can be glued on. I find that the tape is enough to stop the bridge sliding around and once the glue has grabbed, I gently remove the tape; this helps to remove excess glue that may have oozed out.

Once the glue has dried the holes for the pins are drilled into the soundboard and the bridge pins fitted. You must a get a tapered reamer for this.

Hopefully you can see why you need 100% concentration!

A number of readers have asked why a give my secrets away? Put it this way, I’ve watched my Stefan Grossman “Fingerpicking Country Blues Guitar” DVD many times and can I play like Stefan? You’ve seen my YouTube demos!

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Blogger Peter Brown said...

Thanks for a great insight into your process Gary. I'm attempting the very same operation on two guitars over the coming weekend so your photo essay is timely, although on one instrument I masked the bridge area prior to finishing for the sake of comparison. Did you use hide glue to attach the bridge?

1:15 PM  
Blogger Gary Nava, Luthier said...

Good old Titebond!

4:20 PM  
Anonymous Anonymous said...

Do you use the Titebond liquid hide glue or original?
would you use the same glue in all the construction?
thanks chris

1:22 AM  
Blogger Gary Nava, Luthier said...

Titebond original- I did post on adhesives that you might find interesting.


5:00 PM  

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