Re: mandola graduations
I'm not a builder. But you mentioned that an oval hole was in your plans. Just a a comment about all braces being more or less equal. I'll suggest that a exception is the single transverse brace that Gibson put on their oval hole instruments in the first quarter of the 1900's. I posit that this was certainly an inadequate design. I say this based on the hundreds of these instruments out there with top sag under the bridge.
Due to current budgetary restrictions the light at the end of the tunnel has been turned off -- sorry about the inconvenience.