Martin Tiple can be a joy to play.
 

1947 spruce top, mahogany b/s. The neck was reset, refretted. The tuners, 12:1, turn unevenly, mostly stiffly through a complete rotation, oiling helped a little, but a smooth set would be peachy. Once zeroed in, the strings intonate perfectly at the 12 fret. The action 1.7mm (.070") at the 12 fret.

Tuning and gauges:
b
.09
.09

g
.12
.24
.12

D
.14
.32
.14

b
.10
g
.22