Martin 000-28C Conversion

[Howard Klepper]

It's conversion time again. I like doing them, and as long as folks like seeing them I will keep posting, and explaining the process. I also will be presenting a session on conversions at the Fretboard Journal's Fretboard Summit this November. I hope to meet some of you there.

This one is a 1948 Martin 000-28C classical.

As most vintage Martin fans know, the C classicals used Martin's 12-fret body shapes, while the G classicals used the 14-fret bodies with 12-fret necks. This means that a G conversion requires a new 14-fret neck (unless it is going to be a Norman Blake), while a C can keep its original neck. That's the good news. The bad news is that the necks are a full 2" wide, and not reinforced for steel strings (they come with an ebony neck bar). They also have classical tuners.

The first time I saw one of these converted, over 40 years ago, the conversion consisted of giving it a belly style pin bridge, radiusing and refretting the fretboard, and stringing with extra lights. As I recall it sounded thin and weak. To my way of thinking, by the time you have rebraced the Sitka top (which often is on the thin side), and tried matching finish around the bridge, you may as well be giving it a new red spruce top and a style upgrade.

Regarding the neck, the original fretboard would end up thin at the edges after radiusing it; and there still is the problem of neck reinforcement which requires removing the board. And not too many people want a 2" wide nut on a steel-string. Because the tuners used on these (old Waverly, I think) have aluminum rollers, it is not hard to turn the roller shafts down to 1/4" diameter where they are exposed at the slots. But they are not great tuners and will have 50+ years of wear, so unless someone wants to keep them, I'll fill the roller holes and replace them with new ones.

So--If you want to end up with a steel string neck, the fretboard needs replacement and the neck needs more reinforcement. For the latter, I will keep the ebony rod and add a 1/8" x 3/8" carbon fiber rod on either side of it. And to get the neck to the size and shape of a 1930ish 12-fret 000, I will narrow the nut to 1-7/8". The headstock is wider on these than on an original steel-string; it can take about that much narrowing at the nut--1/16" on each side-- before it starts to look funny. And the neck gets a refinish. A bit more good news: most of these are long 25.4" (nominal) scale.

So we are off. Neck steamed out:



Fretboard removed with a heat blanket for glue release:





Meanwhile, I start a nice red spruce top--one I got 10 years ago from John Griffin. I'm going with a Style 40 rosette. Those are not color streaks in the spruce--they are superficial marks left by my thickness sander.

I was going to use a method for dropping the new top inside the existing binding (John Greven describes this on his website). Here I am ready to rout the top to fit. The soundhole and rosette are done first:



But after taking a closer look at the back, I decided to refinish the back and sides, which removes most of the advantage to keeping the old top binding intact. The back on this one looks superficially good--not majorly scratched or with bare spots. But closer examination showed a pebble grain kind of surface, lots of burnishing from belt buckles, and some bubbling of the finish, possibly from heat. I decided to refinish everything, and so I took off the top binding, which gives me better access for fitting the new top and its braces into the liners.

Another thing that is typical for older Martins is that the back braces are loose. That's what happens when you glue braces on a panel running cross grain. Also, I see more of this with hide glued back braces than with PVA glue. That may be in part because hide glue doesn't creep; I think it also weakens over time with exposure to climate variations.

Every back brace is loose, as shown below. If a brace is loose over more than half its length, I like to remove and reglue rather than working glue under the loose part; I have more confidence that it will be glued solidly.



Hide glue for this. I do have some doubt about whether it is ideal in this application, but I use it any place where it was the original glue and will be expected by future repair people. So back in they go:



More to come. Thanks for watching.

[psychojohn]

Nice work !! In some ways seems even more challenging than starting from fresh !!!

John

[tkoehler1]

A fascinating process to watch thank you Howard!

[iim7V7IM7]

I always enjoy these threads Howard...

[darko]

Thanks for sharing your knowledge Howard. I like these threads.

[tadol]

Its great to hear your philosophy on the choices you have to make with a project like this, especially how it differs in comparison to a new build -

The awareness of a future luthier getting the opportunity to work on this and the choices you make during this re-build are very informative. I know it takes time to document both the process and your thoughts while doing it, and I have to say thanks for taking the time and making that effort -

[billgennaro]

Originally Posted by tadol

....I know it takes time to document both the process and your thoughts while doing it, and I have to say thanks for taking the time and making that effort -

I second that emotion. Thanks, Howard.

[Howard Klepper]

Thanks for watching. I'm sort of using the process on this guitar as a way of organizing my thoughts for my Fretboard Summit presentation, so it helps me, too.

Back braces reglued:



Ebony fretboard inlayed in Style 40-42. It will be bound with ivoroid, which is what distinguishes Style 40 and 42 boards.

[Howard Klepper]

Fretboard bound and fretted:



Top braces in. I glue them in full dimension and then shape. Below the X the pattern is about that of a 1930ish Martin. Above the X I use an A shape with tall soundhole braces that run under the Upper transverse brace, because I think it has clear superiority to the low soundhole braces and "popsicle stick" across the upper bout.



Braces rough shaped by chisel and finger planes.

[jmat]

This will be fun to watch Howard, I look forward to your updates. The back wood looks great from the inside - the re-finished guitar will be spectacular!

I am attracted to the idea of this, in fact back when when you built the 25" scale OM for me you had mentioned that you convert Martin classicals when you can find them. Love the OM but I can tell you it gave me pause while contemplating the commission.

Thanks for posting, such a fun process.

JM

[justonwo]

This thread is awesome.

[Aculadd]

I agree. Great thread. Thank you for posting this.

[Howard Klepper]

Thanks for watching!

Final brace shaping done:



Gluing on the top:



Reshaping the neck:



Installing abalone purfling. I'm doing this the old-fashioned way: solid shell, about 150 separate pieces glued one at a time. A lot more work than abalam or zip flex, but it has a vintage look that laminated shell doesn't get.

[Harmonist34]

Beautiful work, Howard!

[Steve Kinnaird]

Originally Posted by Howard Klepper

Installing abalone purfling. I'm doing this the old-fashioned way: solid shell, about 150 separate pieces glued one at a time. A lot more work than abalam or zip flex, but it has a vintage look that laminated shell doesn't get.

That's the truth! It's a subtle thing, but noticeable. Kudos for the extra trouble you're taking.

Steve