[Harp-L] Cracks in combs



Having fixed or replaced many broken chromatic combs over the years I've found the problem isn't so much with the comb as it is with the cover plate posts.
The comb is the victim of stress cracks not the cause.


The posts are slightly pointed at the tips. Under normal humidity conditions they create no problems. Under low humidity conditions the wood starts to contract.
As it contracts at the post tip stress is placed on the wood. Add the downward pressure you use when holding the harp and you have the makings of a crack which usually extends from the posts to the front of the harp. There are other stress points as well but that is the most common area.


A couple ways to solve this is to remove the reedplate, insert the post through its hole and snip off the end of the post to be flush with the bottom of the plate. You can use silicone glue to reattach the posts once the reed plate is remounted with nails. If you use screws to remount the plates you can reattach the posts with gorilla glue to make them permanent. Remember: you have to flip the harp over to tap in the bottom nails. It's difficult to do with permanently mounted posts. Thats why I recommend silicone glue.
I use to solder them in place but found the next method to be the best.


Another method is to tap the post hole to fit a 0-72 or 2-56 machine screw or metric equivalent. Screw in the screw so only enough to match the height of the original post then cut off the excess thread to fit flush with bottom of reed plate. You don't want to leave excess screw thread in contact with the comb or you will still have a stress spot.

mike




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