Originally Posted by
etbarbaric
Hi Marijan,
No problem at all. I enjoy these conversations very much (as I know Alex and others do). I'll look around for the details of the bridge and nut measurements that we used on my Fabricatore. They were taken from Alex' 1794 example which had its original nut and bridge.
As to the bar, I would approach it slightly differently. Unlike a violin top that is carved to a rather fixed shape, these mandolins had very thin (and fairly uniformly) thicknessed tops. This means that they are extremely flexible in a longitudinal direction (across the short dimension of the top). If the bars were off, you would be able to bend the spruce top back and forth easily with your hands (along the grain, not across). This flexibility seems alarming at first, but it is perfectly normal. In most cases, the top is designed to take its shape from the bars. You will notice that these bigger (taller) bars are on either side of the sound hole... no doubt to reinforce the top where it is missing a large chunk of wood!
The bar is there not only to reinforce, but also to "tension", or stiffen, and give the top its shape. In other words, the bar _intensionally_ has a curved "face" that is glued to the underside of the table, and that curve should not be removed. The idea is for the flexible top to conform to this curve once the bar is glued in place. The top may well be flat now, but it likely was initially slightly convex (curved outward in a longitudinal dimension). This curve not only helps the top resist the downward pressures it must, but it also "tensions" the top to make it stiffer, which helps in sound production. Think of the bar as a little wooden spring. Of course, this is also why the ends of these bars typically come loose (or split) over time, since they are under tension.
That said, depending on the glue joint, you may well want to remove the bar, reglue the split, and then reglue the bar to the top. If you look back at the thread about my 1793 Fabricatore, you'll see that one of the bars on my instrument had an unfortunate knot at the end, which had long since popped out due to the tension (in almost an identical location to your split!) Larry chose to fabricate a new bar in that case since material was actually missing from the bar. In any case, the curve of the bar should be retained, IMHO.
Let me know if this doesn't make sense.
Best,
Eric
ps - What does your neck block look like from the inside? :-)
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