building period pre war Martin guitars

[tippie53]

for those of you that are interested in building pre war guitars here is something that may interest you. Compared to modern Martin kits the big differences are often the ones not notices
A Neck block
on a modern martin the neck block is not as thick. The pre war block changed in 1939 from 1 9/16 in to 1 3/8.
B Popsicle Brace
We see this come in about this time. After 39 when the block was made smaller there was a rash of cracked tops. To take care of this , the Popsicle brace was used.
C Transverse Brace
The prewar transverse or truss rod brace in older martins was 3/8 wide and 9/16 in high . Modern ones are 1/2 by 1/2
D ends of the braces
The x braces went through a few changes. In dreds I have seen scalloped end , curved tapered ends and straight tapered ends
E glue
Hot Hide Glue
F Bridge plate
These were Maple and they were as narrow as 1 3/8 in today 1 3/4
G Brace Shift
I don't know why they call it forward shifted when the braces were actually pushed back and the angle changed.

The tops were brought into the plant at .117 in thick today they are .125 . I have seen tops as thin as .095
H Rosette
the material used was different in size to modern plastic.
Here is a picture of a pre war top
specifically 1931 OM this will show a rosewood plate that replaced the original maple

[tippie53]

1939 Martin Dred top This is one of the first ( rear shifted) braced guitars. Not the shape of the braces and the X angle of 99 degrees

[B. Howard]

As always, lots of great info here......Thanks much John.