Correcting some interesting home "lutherie" on a Martin

Lutherie blog

Hey folks welcome to my second installment of Dooley Guitars blog. Today we're going to look at a unique case of this Martin dreadnought and the trauma it has undergone and ultimately its salvation. 

To give you an idea of what has happened to this instrument take a look at this


You are looking at the inside of the guitar at the neck block area. There appears to be 4 wood screws which are much too long wrapped with twine or rope of some sort and then gobs of epoxy dumped all over everything.

A woman had fallen on this guitar while it was on a stand (he actually has a video of it happening, it's cringe worthy indeed) and completely destroyed the neck joint. The owner was advised that about $900 of work could be done only to have a guitar worth a little less than that when finished. He opted not to fix it and a friend of his took the guitar for a week and came back with this.

 

Amazingly, the guitars plays decently and the projection off the end of the fingerboard is only about 1/32" above the bridge. The reason it came into my shop is that it was playing very sharp compared to the open strings when fretted anywhere on the board. This tells me that the distance from the length from the voicing point off the nut to the crown point of the saddle is too short. By taking a quick measurement of the scale length (measure from the front of the nut to the center of the 12th fret and double that distance) I verified this. I found that the high e string's length from nut to saddle was exactly the scale length and the low e was only 4/32 longer than the scale length. This is not enough compensation to play in tune up the neck. When the earlier "repair" was done material must have been removed from the heel of the neck. The solution is to plug the saddle slot with a piece of ebony and re-cut the slot further back, in this case moving it about 3/32". Unfortunately this would put the bass side of the saddle very close to the bridge pin holes and create too much of a break angle for the string over the saddle. So I compromised and decided to move it 1/16" and hope for the best on the intonation. 

Here I am thickness sanding a piece of ebony on my mini drum sander from micro-mark. This machine is extremely handy for making nuts, saddles and bridges as well as for this job, especially in a shop with limited space. The drum is only about 6 inches wide, but its as accurate as any drum sander I've used.



Here is the plug installed, but not cleaned up yet.



Preparing the jig for the laminate trimmer to re-cut the slot with a straight cut 3/32 bit.

Now the slot is cut, time to re-install the piezo element for the pickup and make a new saddle. Here I found that battery bag for the Fishman pre-amp was attached by Velcro to the underside of the soundboard right next to the x brace. Talk about an unnecessary tone suck! I moved it where it belongs attached safely to the side of the guitar on the treble side where gravity wants to put it while the guitar is playing position and not impeding vibration of the soundboard.




Ok the saddle is installed, time for the moment of truth. 
 Success! The high e intonates perfectly and the low e is still a little sharp but much, much better than it was previously. Importantly, this is also what I expected to happen since I couldn't move the bass side of the saddle slot as far as I would have liked. I'm very pleased by this outcome and most importantly the guitar sounds great! But uh-oh when plugged in the balance of volume from string to string is terrible. What could be causing this? I just re-cut the slot so I know the bottom of the slot is flat and I just made a new saddle so I know it's making great contact with the under-saddle piezo element. Ah, the break angle being so great over the bass side of the saddle combined with the relatively tall saddle profile due to the neck angle means the pressure disbursement is uneven and the result is that the low e string is a few times louder than the d and g strings. I add a piece of thin adhesive copper foil to part of the underside of the saddle to add a slight bit more pressure pinpointed where the strings are sounding dead through the pickup and voila! The balance sounds great again.



This guitar has been through a lot and its a miracle that it plays at all, but it really does have a nice sound to it, albeit a bit bright. Due to the stiffness of the neck joint, the neck set may not inch forward over the years as a typical dovetail joint would and ironically this franken-Martin may outlast others that came off the Martin line at the same time. 

Thanks for visiting my blog, see you soon.

Shane Dooley 
Luthier and owner of Dooley Guitars

My shop is located at 460 Main Street in Longmont Colorado inside of Guitars Etc.