Mark Stutman @folkwaymusic and I put our heads together (mostly his) and started down this winding path nearly 5yrs ago. We’d both cringe every time we saw my Martin Belly Reducer cauls installed on Gibson-type guitars. They are both referred to as “flat-top” guitars but Gibson tops are NOT flat and that radius is part of what makes them sound like Gibsons!
Those of you familiar with Gibson guitars will understand why we questioned whether this was possible at all. Every time we thought we’d found something that could be considered “standard” we’d get thrown another curveball. Then I’d have to remind Mark of that image of the flat Martin cauls clamped on the radiused Gibson tops, light a fire under him and send him back to the drawing board. These seven aluminum cauls represent the best matches we could come up with for vintage Gibson-style guitars, but be prepared to alter (bandsaw, sand, file etc) an angle or length here and there.
The Martin cauls are radiused in only one direction, front to back. These cauls are radiused front to back and side to side, so the centerpoint is the top of a (15’) sphere.
Happy distorted top correcting!
Mark kindly agreed to make an instructional video which you can find here: