Crawls Backward (When Alarmed)

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Making a New Bridge for the Martin O-18T Guitar

The original bridge on the O-18T is long gone.  Someone had fabricated a replacement from a 6-string guitar bridge long ago, and it doesn't look very good.  It's a shame to see such a fine instrument with a poorly done bridge on it.

So I'm making a new bridge that will be a facsimile of the original Martin bridge and hopefully will be an improvement on the bridge that was on the guitar.

I happen to have a new 5-17T from the Martin Custom Shop on hand.   The trickiest part of the bridge is the curve on the end pin side.  There are templates online for a 6-string bridge in this style, but not a tenor bridge.  So I use a compass to copy the curve onto a sheet of tracing paper.

Then, armed with that curve and the measurements from the 5-17T as well as the markings on the top of the O-18T where the old bridge was, I can cook up a template to use to cut the new bridge.

You see the template here lying on the top of the guitar.  Looks pretty good I think.

Here's where I could really use a bandsaw.

I have an ebony bridge blank, and I need to cut about a third of its thickness away (lengthwise) so it will be close to the final thickness I need.  With a bandsaw, I could just slice it off.

Instead, I use a coping saw to cut most of the thickness off, then I use my trusty ROSS to sand the blank level.  Makes a lot of ebony sawdust, which seems wasteful.  So I bag it up to use as fingerboard filler in the future.

Now I can glue the template to the blank and use the trusty coping saw to cut close to the pattern.

This part actually goes fairly quickly, and while doing this cut I remind myself that Torres didn't have a bandsaw - he did it all by hand.

My new best friends - coarse and fine Dragon rasps.  The teeth are handcut and are super sharp.  I used the fine rasp to trim down the 'wings' of the bridge, and then followed that up with files and sandpaper.

The other reference I had on hand were two photos from Robert Corwin's incredible Vintage Martin web site.  He happened to have some pictures of an orignal O-18T bridge which really helped with the shaping.

I think my use of these falls under the "personal use" clause in copyright laws.  I hope.  I used to work with librarians who drilled that in to me, so I think I'm ok.

I needed a mental break from shaping the bridge before I took on the shaping of the curves.

So I moved on to making a patch for the bridge pad.  The pad itself is in good shape, but the string holes have become oval-shaped over time.  I made up a small, thin patch of maple to glue on the pad to give the string ball-ends something to latch to.

The patch is only about .028 of an inch thick (0.7mm) - I kept it small and thin to not affect the tone of the guitar.  I even beveled the edges a bit to make it look like a real luthier did the work.

Here's a mirror image shot of the new patch after gluing it in place.  It just covers the holes.   I used hide glue - which is what Martin used originally.

You can see how thin and delicate the bridge pad is.  Really wonderful - it's just big enough to provide some support under the bridge, but not big enough to dampen the top.

If you look closely, you'll also see a previous repair to the top seam - see the two diamond-shaped cleats.  Nicely done.  They could have been a bit smaller, but they were clearly done by a pro.  Very nice work indeed.

The other detail is the scalloped braces.  This is a feature of all pre-war Martins.  I'm pretty sure they're spruce - and look at how nicely carved they are.  Wonderful craftsmanship!

That detail is why I try to do the best work I can - to honor the people who took so much care in building this guitar in the first place. 

 
 
 
 

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