National necks generally came in two flavors: maple and mahogany, with variations of each. These variations consisted mostly of different wooden center stripes, or perhaps a layer of birch or basswood between the neck and fretboard. (Due to a shortage of thick enough neck blanks.) I have mainly seen these necks on Collegians and 14 fret Style Os.
Neck reinforcement varied between a quarter inch by half inch solid steel bar and a half inch hollow tube that sat in a rather large routed out channel. Unfortunately neither were secured very well. The hide glue that held these truss rods in place has often deteriorated, leaving the rod loose in its cavity. Also, with nothing for the rod to butt up against, this method proved to be totally ineffective!
Largely due to the size of most National necks, there is enough beef to hold the neck straight once it has been heat-pressed, provided that the fretboard is well glued to the neck. I find after being misaligned for a number of years most Nationals have a loose glue seam around the 12 fret where the neck meets the body.
Fretboards were either made of ebony, rosewood, or maple, the latter coming in two varieties: natural and dyed. The dyed ones often pose an interesting problem. The dye that was used slowly deteriorates the cell structure of the maple fretboard, turning these into various states of wood pulp. It is this deterioration, when combined with inferior neck reinforcement, that yields a very warped neck. Depending on the degree of this deterioration, sometimes it is best to replace the fretboard and stabilize the truss rod.
I can provide seamless fretboard replacement and truss rod stabilization.
Often times over the years, the fretboards shrink up a little. Very few Nationals come through that dont have loose frets. In extreme cases the fret ends protrude from the fretboard, pushing the binding with it, or causing bumps to appear in the binding. These too can be flawlessly repaired.
This drying out of the fretboards also causes problems with refretting. The dry brittle boards are prone to chip severely when pulling the old frets. This problem reaches critical mass when dealing with the dyed maple boards. They can easily blow big chunks.
Combining my experience and a helping push from Rick Turner, I have developed a successful method for fret removal. My refrets are sweet and neat, each fret kissing the fretboard, with the fret ends polished and defined.
Please refer to the price list for estimates...