Advice and questions on making and fixing instruments
User avatar
By the kid
#37558
I would wonder about the 1.5 cm thickness of the 'optimum djembe'. Is that really thick enough to hold a thick skin highly tuned? I wouldn't think so. It may hold it but could warp too. Esp a non african wooded djembe. Better to make sure that has the extra strength of a few extra mm. I though shells should be at least 1.5 to 2.5 cm. If it is 1.5 and the inner bowl is carved a touch too much you end up with a weak point. 1.5 should be an minimum thickness imo. If your aiming for djembe of 7 to 8 kilo then that thickness is prob necessary but djembes weighting 10 kg's or more would be thicker i would have thought. Maybe there are large variations in wood weight too.
User avatar
By michi
#37559
It depends on the density and hardness of the wood. But I agree, 1.5 cm would be a lower limit. I'd be more comfortable with 2 cm for main part of the bowl. Down near the waist, where the shell is held together only by end grain, I'd hope for something closer to 4 or 5 cm.

Michi.
User avatar
By ternarizator
#37560
You're right, 1.5 cm is the lower limit, but it can work : one of my djembés was made of hornbeam with a thickness of 1.5 cm almost all over (except above the "waist"), then mounted with a thick billy-goat skin, no problem. It also depends on the carving technique : using an adze, it's better not to carve too thin, while by woodturning, it can do very well, of course depending on the dexterity of the craftsman.

Vincent
User avatar
By michi
#37561
Yes, with really hard and dense wood, 1.5 cm is fine. I had a Gueni shell that was like this, with a quite thin-walled bowl. No problem, the wood was plenty strong enough. I had both calf and horse skins on that drum cranked up seriously high, without any problems.

Still, 1.5 cm is definitely on the thin end of the spectrum. My other drums are in the 2–2.5 cm range.

Michi.
User avatar
By Carl
#37569
interesting thoughts here...
My preference is for dense wood with a relatively thin shell. If the shell is less dense, I would want it thicker to give it more mass for better sound.

So I think that a drum that was not thick enough to hold the tension of the skin would also not have enough mass to sound good... self correcting! ;-)

On the other hand, I'd hate to hear a metal djembe (high density, so it could be thinner by my logic above)
On the other, other hand, I have heard of good things done with ceramics. as with other posts on these subjects, there are so many variables (type of internal carving, overall shape, skin quality) it is hard to come up with hard and fast rules!

C
User avatar
By drtom
#37588
1.5cm is fine for African hardwood. I've skinned djembes that are a bit thinner, and they hold up fine.

If you look carefully at Vincent's illustration you'll see it's the trumpet that is 1.5cm. The bowl is thicker, especially as it nears the waist, so his optimal djembe should hold up great.

But you guys are getting into the optimal design for structural integrity. I believe Johny was interested in the acoustic integrity of the drum. Of course, without structural integrity the acoustics are probably going to suck.
ternarizator wrote: I just mentionned it as an example, for information, to help Johnny in his search.
And Johny will probably find it useful, as will plenty of other folks. The proportions of your optimal djembe are well within the range of the typical djembe I encounter. Based on his last post, I would guess you and others have convinced Johny to play it safe.

I had such high hopes for Johny.
User avatar
By the kid
#37592
But you guys are getting into the optimal design for structural integrity.
And longevity of the drum. Plus the sound doesn't suffer at all due to a drum been thicker than the minimum. Be generous with the wood i reckon. Let it speak.

The guy is looking for a bassy drum so the extra wood is no harm at all.

It's hard to strictly define the sound of a shell due to thickness, but i like the sound of thicker shells. I also like the sound of thick skins too. To me the volume is louder with thicker skins although i've heard other opinions in it.

The older school may have been thinner plus some tourist drums are overly thin imo. But all the better looking modern drums seem to have thicker walls. Sound is not compromised at all. Could it be better, maybe/probably. I think as the tension went up,then there is a realization with carvers that the shells need to be tougher.
By Jithin
#38682
Hi guys,
i am trying to build a drum. my dimensions are
head dia - 10 inch
neck dia - 3.3 inch
botoom dia - 5 inch
length -20 inch
bowl height -10 inch
michi mentioned about the surface finish of inside shell, can you explain it more. finish should be rough or smooth ?
By Jithin
#38683
michi wrote:
Sat May 27, 2017 1:34 pm
ternarizator wrote:Hello, here's my idea of an optimal djembé, if it can help...
Looks damn close to my idea of an "optimal" djembe, too!

Those are sensible proportions. Pick the right wood, texture the inside surface, and you'll have a good drum.

62 cm is at the upper end of the height spectrum, I think. Not that it's wrong, just that it's "tall and fine". Once you get to 63+ cm, most people start to think that the drum is is too tall because they have to "reach up". Anything shorter than 58 cm, and people start to feel that they have to "reach down".

can you please explain about the surface finish you said. should it be rough or smooth.

So, to me, the sweet range if 59–61 cm. That's a good height for almost everyone, except for really short or really tall people.

Michi.
By bighammer
#39363
I'm liking that drawing because that's pretty darn close to what I turned on my lathe. I made one form maple a couple years ago, but donated it for a silent auction. (I was outbid in the last minutes) This a replacement but out of walnut this time. Just bent and welded rings for it today.