MIMF

I have been making kalimbas and having trouble figuring how how certain dimensions effect the sound and in what way. For instance, how does the hole/body size effect the sound as well as thickness and density of materials used. Is there a golden ratio.
This one, http://rs1380.pbsrc.com/albums/ah188/Jo ... 1422978238 I am having trouble with the high notes sounding harsh and not registering a single note. It seems like the high notes cause the whole thing to vibrate so much that other keys will vibrate with equal intensity. When I hold the other keys down will get a clear note but with out it sounds harsh. The low notes seem to do the same but much more subtlety so they sound amazing.
I have tried thinning the keys on the high notes and that seems to help a little but the harshness is still there. Tried dropping to a lower key but then my low notes loose volume, a lot. Tried adding mass but reducing density of the body by pouring gorilla glue inside, hoping to some how dampen the vibrations, no luck. Was thinking of adjusting the hole size but figured I'd ask around before I do anything irreversible.
The keys are bike spokes ground down. Any advice for a beginner would be appreciated. I hope to move from xylophones and lamellaphones to ukes soon.

Hi Eddie,
There might be some tips in our library, have a look here: http://www.mimf.com/ksearch/ksearch.cgi ... y=50&all=1

I have a kalimba from the MIMF build way back when and I think they used tines from a leaf rake.

A tricky thing about kalimbas is the overtone series is significantly out of tune with the fundamental pitch ( metal stringed instruments, too, but higher overtones and quieter ones and so not as much of a problem-) the third mode of vibration is two octaves and a somewhat flat major second from the fundamental. Typical way to damp those modes is to make the tips heavier with weights ( try lead fishing sinkers, the crimp-on kind),thin the rods in some spots by forging/filing, or both. Things like rake tines also make a nicer sound, like Charlie says- maybe because they mostly vibrate in one plane they have fewer harmonics

Bart Hopkin's book on musical instrument design is handy for some kalimba calculations, has a lot of basic formula for a variety of things. You might get it, since it sounds like you are going to try making a variety of things.