Evaluating a 70's D-28

"Before"

I'm often asked about 70's Martins, particularly D-18 and D-28's.  The question usually goes like this: "I just bought (or am about to buy) a 197x D-28.  What sort of things should I look for?"  A 1971 D-28 with all the typical 70's issues just landed on my bench and I decided to photo document the evaluation.  Here we go!

The first thing I do is check the saddle location.  The "zero" end of this ruler is resting in the middle of the 12th fret.  The penciled in "B" (for "bass") should be right in the middle of the saddle at the spot where the low E crosses over.  Likewise, the "T" is for "treble".  As you can see here, this saddle is over 1/8" off.  Sometimes I can re-route the saddle slot but in this case, the slot needs to move too far back.  This guitar is going to need a new bridge, a new fingerboard, or a shim under the neck to get intonation right.  This saddle is so far off that I might have to use a combination of solutions to get it right.  

Options for dealing with 70's bridges.

The bridge on this particular guitar is loose. That's a .004" feeler gauge with about 1/8" under the bridge.  No question that this bridge is coming off.
This guitar has worn frets that have been filed at least once and have a flat-top instead of a rounded crown.  There's nothing I can do to help these frets and the guitar will not play right like this.  Fretting will be difficult due to the low height, and the resulting note will be buzzy due to the flat-top making for a poor "bite" on the string.  Nothing to do here but re-fret and since all the frets are flat-topped and low, I need to re-fret the entire fingerboard.
The old black pickguards were fastened directly to the wood.  Over time, they shrank and either pulled loose or caused cracks at various places.  This guitar has both- it has a typical crack under the B-string (not shown) and it's peeling off.  We'll either stick this guard back down with tape, after filling in the bare wood, or make a new pickguard.  Since the guard is shrunk, if we re-use it, there will be a small tan line around the guard, but it won't be too bad.
This guitar clearly needs a neck reset.  A straightedge running down the fingerboard falls well below the bridge and there's not even string tension on the guitar.  Under tension, it's going to fall probably 50% lower than this.

 

Inside the guitar  we have the huge Indian RW bridgeplate that Martin used in the 70's.  The holes are worn and the ball end of the strings were starting to pull thru the plate.  Plus, Martin ran the grain of the plate perpendicular to the top grain. This offered very little anti-belly strength and since the pins were all on a single grain line, the plates tended to crack, reducing the anti-belly resistance even more.  Whenever I see a bridge pulling off, I look at the plate, and sure enough, this one's warped.  Plus, I personally don't like the "dark" tone of RW bridgeplates and much prefer the neutral tone of maple.  My preference would be to replace this plate with a smaller maple one with the grain running parallel to the bass X-brace.

This guitar (a different one) has an undersaddle pickup.  I intensely dislike undersaddle pickups.

Still inside the guitar, I look at the popsicle brace area for cracks.  The popsicle brace is supposed to prevent cracks along the fingerboard, but I still commonly find them.  I couldn't get a photograph, but there is a very fine crack starting on the left side of this picture.  We'll see it from outside the guitar in a minute....
Here's the small crack from the outside.  It's nothing to get upset about yet, but the fact that there is the start of a crack is something to nip in the bud before it gets worse.  My preference here would be to remove the popsicle brace and install a trapezoid brace running from the neck block to the large soundhole brace, with grain running parallel to the top.  This is how severe cracks like this one are fixed, so I consider my brace as a "pre-fix", and it still keeps the upper bout free to vibrate, which the popsicle brace does not.
I check for loose braces while inside the guitar.  This is a different guitar than we've been looking at, but here is an obviously loose brace.  There's no crack in the brace so this is not a big problem- just glue it and clamp it.  Check top and back braces.
Here's the stock Grover Rotomatic tuner.  I hate these things.  They've got screws and bushings galore and they're very heavy.  This Rotomatic is very loose.  The cap will be pulled back in when I tighten the screw inside the tuner button, but the pressure washer on the shaft is flattened and not doing its job.  My preference is to replace these things with open back Gotoh or Waverly tuners.
Check for loose binding.  Binding tends to shrink over time and will either break or pull loose. That's what has happened here.  The binding has pulled away from the body and won't go back down w/out a fight. 
On the upside, the early Indian RW guitars had some nice wood with a generally brighter and snappier tap-tone than more modern wood.  I've found this "pepper speck" wood to be pretty good sounding stuff.
And here's a shot of the top grain. 

At current prices, a full overhaul of this guitar would run:

It adds up, but there is a lot of sound in these guitars once the problems are fixed.  They'll sound a lot like an HD-28 or D-18 with 30-40 years of age.

Go here for some "After" pictures

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