Day 175: In the Green

After input from master builder, Owen Daly, and much research and deliberation, I believe I've come up with the proper placement trajectory for the bridges. This all began when Owen noticed something might be a little off with the placement of the bridges that would affect the ultimate tone of the instrument. In the absence of having specs on the original instrument this copy represents (the A. Ruckers 1640 single at the Yale Museum), I found string speaking lengths in "the O'Brien book" for an A. Ruckers 1637 single and recorded them (see table below).

Now, the instrument in Ernie's eBook Most Excellent represents a ravalement (later alteration) of the instrument, making it wider, which I believe would affect the placement of the bridges. Yet, I had a nagging suspicion I would want to stick with the original placements. This presented a secondary problem: I didn't have a drawing or any detailed information on the original instrument.

This is when Owen came to the rescue by loaning me his copy of the drawing done by R.K. Lee in 1971 of the original instrument at Yale.

This was a revelation. Based on the drawing, I created a spreadsheet comparing the 8' and 4' string speaking lengths (typically done for all Cs and Fs as a quick gauge) using all the data I had at that time. All measurements are in millimeters.

8’ Miller 1640 Yale 1637 AR* 4’ Miller 1640 Yale 1637 AR* c''' 171.5 169.5 171 c''' 89 80 83 f'' 257.5 259.5 258 f'' 132.5 126 129 c'' 331.3 345 348 c'' 174.5 169.5 173 f'  485.5 512 531 f'  253.5 245 258 c' 623.5 677 698 c' 332 324 338 f 884.5 927 963 f 450.5 450 474 c 1073 1111.5 1165 c 544 545 580 F 1320          1368 1351 F 695 697 717 C  1393.5          1409 1366 C 800.5 787.5 736 *Germanisches Nationalmuseum, Nuremberg, No. MIR 1073

As you can see, the figures in the tenor and at the hook vary a bit, yet all of the Yale 1640 figures are either very close or nearly the mean between Miller's copy and the 1637, especially with regard to the 8' numbers.

At this point, I marked out the 1637 and 1640 pins on the Miller plan. The orange marks represent the 1637 and the green represent the Yale 1640.

I now must make a decision: Do I follow the Yale green points or Mr. Miller's CAD drawing? Interestingly, when I laid the bridges onto the R.K. Lee drawing, they were a nearly perfect fit to the Yale 1640 marks with little final bending during glue-up required.

My inclination is to follow the green marks wherever they may lead. Regardless of my decision, the bridges will be glued down this week. Finally.

Until next time...