Thanks for your interest in the tongue drums -
I apologize but I did not keep precise dimensions for my tongue drums. I made about six in total, mostly as experiments to discover how the various materials and sizes worked. I made some with red oak sound boards and pine sides, one with a mahogany board and oak sides, one with a hard maple and etc. I gave all but this one of away so no longer have them around to measure, but the sound boards on all of them were of a similar size.
I have taken some pictures which may help you on relative sizes and dimensions. The background is a grid with 1” squares, and I have laid my rule directly on the drum to help in some pictures. There is some information online you can find as well which will be of help. I remember I printed out some schematics I found online which I glued onto my stock to guide the cutting. I was pleased with the results in any case.
The best sound seemed to be with the one made from the traditional padauk material from Africa, and which is pictured here. The hard maple and mahogany also produced pleasant sounds, and the oak not quite as nice, but still OK. My recommendation would be to use maple or mahogany (not Philippine) since you don’t need much, and it is easier to find than the padauk. I also made various inside depths, from 4” to about 8” inside under the sound board. All the ones I built have 6mm high quality ply bottoms and fairly small sound holes cut in the ends. The bottoms were screwed in place onto thin fillister cleats glued to inside of the sides and ends, and recessed enough so the bottoms are slightly recessed so they do not contact the surface the drum rests on. All the other joints were glued. I found it was good to glue on small felt furniture pads for the box to stand on to isolate it from solid contact with whatever it is placed on. I cut the linear parts of the tongues with with a very thin kerf battery-powered panel saw and finished the curved parts with a 24” scroll saw. Sanding the sides of the tongues was a challenge and was done mostly with power sander belts cut into narrow strips and used by hand before the soundboards were glued in place.
The outside dimensions of this particular drum are 18” long by 9-1/2” wide by 8” inside depth. Keep in mind the soundboard itself fits inside the sides – maple in this case, so its width is reduced by their combined thicknesses and it winds up approximately 8” wide. The soundboard goes over the end pieces, and I found it makes a difference how far the slits are from the ends. The soundboard is 3/4” thick at the ends, but some of the individual tongues are tapered somewhat in my efforts to ‘tune’ the drums to particular tones – a haphazard and difficult process for me since I am ‘musically challenged’, i.e., I don’t know very much about music. I think with a little research though you could come close to whatever notes/tones you seek. This particular one sounds very nice to my ear, and the ones I made for children seem to be pretty popular with them – then again children just like to make noise sometimes don’t they?
I hope you make a drum – at least one – they are a little addictive! I would be very interested in seeing your completed project.
-- Candy is dandy and rum sure is fun, but wood working is the best high for me!