[Harp-L] Hering wood comb crack viel of mystery lifted



A few years ago, Hering had a lot of trouble with cracked combs on their chromatics. I guess they worked fine in Brazil, but they didn't fare so well up North. Those chromatics since been replaced with plastic on new models, but there are a lot of the old ones out there, so I am passing this along. 
I've spent a couple of months probably thinking about this. This is the one "unfixable" thing about the Herings from a few years ago. The methods for fixing cracked Hohner combs don't necessarily work on the Herings.
 I figured as the U.S. Hering repair guy, I better devote the full power of the Elk River Institute of Advanced Harmonica Studies (This is important stuff we are doing and junk) and figure out what is going on with these things and how to fix them. 

I figured it out.

Now those chroms are attached with tiny screws at the top of the reedplate, as well as regular screws at the bottom.
Now, the cracks usually form at the places drilled for the top screws. I had thought this was the problem. I was partially right. 
The root of the problem is the lamination. At the bottom of the comb, there is a piece of wood with the grain running the opposite way. This is, in theory, a good idea to prevent comb cracks. In reality, it makes comb cracks. 
Wood grain will move to the path of least resistance. It cannot move INTO the body of the comb, so it pulls away from it. The result is, the bottom wood bows out, thus pulling the top piece at an arc toward the bottom of the harmonica, thus putting tension stress on the comb itself, or maybe a better way to explain it: the bottom piece of wood wants to pull it apart like a Japanese folding fan. 
Now the places where the holes are drilled don't have as much wood to hold against the tension stress. That's where they cracked. 

Where this is important is putting it back together. On a Hohner, the crack usually goes through to the bottom, you can fix it at the bottom, then take off the mouthpiece, and fix it at the top, then make the real repair with the reedplates off. 

On the Herings, you have to negate the pull of the bottom piece of wood. You do this by making the repair with the reedplates off, but the MOUTHPIECE ON. 







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