1930 Martin Restoration
Uncle Joe's 1930 Martin
Part 1
Repairing the Martin
Uncle Joe’s poor Martin has seen better days. Photo 2 shows the cracked bridge. Also the entire area of the soundboard has warped upwards to an alarming extent.
In photo 3 you can also see that the white bone saddle has, over the years, been shaved low, in a losing battle to keep the instrument playable.
Also the body is filled with cracks, one of which Pat is evaluating in photo 4. Aside from all this the neck has rotated upwards with respect to the body, further elevating the strings up from the fingerboard, which renders the instrument unplayable.
The first step is to remove the neck. In this style of guitar, the neck is held in place to the body by a tapered dovetail joint secured with hide glue. Also the fingerboard extension (the part of the fingerboard that sits atop the soundboard), is glued down. Fortunately, hide glue is reversible. Heat and/or moisture will cause it to release. So the first step in removal is to heat the fingerboard extension with a heating pad (photo 5).
Once the glue has softened, Pat works under the fingerboard with a putty knife to work it free. Next the neck-to-body joint must be freed. To do this, Pat removes the 13th fret (which is directly over the joint) and drills two small holes into the fret slot and down into the joint below (photo 6).
Then, as shown in photo 7, a basketball inflating needle is inserted into the hole. This needle is attached by a hose to Pat’s espresso machine with the result that steam is forced into the hole, around the joint, and escapes out the other hole. Also, you can see in photo 7 that a special jig has been attached to the body which will force the neck up once the steam has softened the hide glue.
This particular joint takes quite a bit of steam and pressure, a testimony to the very tight-fitting joinery achieved by the Martin luthiers in 1930. But eventually the neck comes off, as shown in photos 8 and 9.
Next Pat removes the bridge, again using heat. Once off (photo 10) we can see quite a bit of damage underneath. Photo 10 shows the bridge removed.
Photo 11 shows the area inside the guitar (taken with a mirror) under the bridge.
Notice that the soundboard is cracked between the holes where the string pegs are fitted. Recall also that this entire area has warped upwards. To correct the warp, Pat moistens it and applies caul and clamp which he lets sit for a week (photo 12).
Once the clamp comes off, the pressure and moisture have done their work and the soundboard is flat again (photo 13).
Directly underneath the bridge and the soundboard is a reinforcing bridgeplate. This particular plate was extremely narrow, much narrower than on modern guitars. In guitars, the lighter you can make the components, the better the guitar will sound but also, the more fragile it will be. Master luthier Alan Carruth likes to say that a guitar sounds best if it is right on the verge of collapsing into itself. This extremely narrow bridge plate (which Martin beefed up shortly after this guitar was made) presents us with a dilemma. To duplicate it exactly will result in the problems Pat has just corrected recurring at some point down the road.
On the other hand, if the plate is made more substantial, there is the risk on impairing the sound quality. Pat decides on a middle course and photo 14 shows the plate he designs, makes, and glues in place under the soundboard.
All the time I am with Pat, a constant stream of customers comes into the shop with their guitars. One couple arrives from Vermont with a unique repair problem. The guitar is a 1945 Martin.
Their visiting young nephew has shot the guitar with his bow and arrow. Photos 15 and 16 show the entrance and exit wounds.
Pat agrees to repair it, giving a time estimate of several months. The repair eventually comes out perfectly. This is why Pat has the reputation as the brain surgeon of guitar repair. The most critical angle in a guitar is that between the neck and the body. This determines the height of the strings over the frets. Too low and the strings buzz against the frets. Too high and the fingers have difficulty pressing the strings down against the frets, meaning the guitar is hard to play. The tolerances are tight — C.F. Martin factory specifications call for the sixth string to be 3/32˝ above the 12th fret with the first string at 2/32˝. 1/64˝ either way is unacceptable. The neck angle is determined by joint between the neck and the body. In many traditional guitars, this joint is a tapered dovetail, which has to fit perfectly. Guitar-making expert and author William Cumpiano calls this the woodworking joint from hell.
In photo 17, Pat is delicately shaving the mortise cheeks so that when the neck tenon (photo 18) is inserted, the entire neck will sit at a slightly lower angle (about 0.75°) below where it did before.
In guitarmaking school with Alan Carruth I have seen students spend weeks to get this joint correct. Pat gets it right in about 20 minutes.
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Pat DiBurro
Exeter, NH
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1930 Martin Repair
03.22.2011
- 1930 Martin Restoration
Introduction
Part 1
Part 2
- 1930 Martin Restoration
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