carving a spiral - what tool?

[davidognomo]

hi guys

sorry if I'm repeating an issue that's already been answered, but on my search here on the forum, didn't find an answer.

so,

I have one of those Thai made djembes carved by a mechanic sistem, all simetric. Thinking of skinning it, and, following some suggestions here of the forum, thought of carving a spiral pattern on the inside of the djembe - no harm done, might as well do something that might actually improve the sound.

What tool can I use for that?

thanks

[michi]

What tool can I use for that?

Ah half-round carving chisel should do the trick:

Carving chisels

images-1.jpeg (6.51 KiB) Viewed 566 times

Let us know how this turns out please! I would expect the sustain of the drum to get shorter so it rings less.

Cheers,

Michi.

[Trog]

I used a pencil grinder with a round metal bit in it and used coconut oil on the wood after.

[Rhythm House Drums]

The bent gouge as Michi has shown will do good for the lager diameter around the bearing edge and be able to go about 3/4 the way down, but you'll have problems lower in the bowl and doing the bottom, if you planned on that as well.

A sharp scorp is your best option. It will get down in there and it cuts on the pull stroke. They have smaller one handed ones or for taking large chunks of wood they have larger two handed ones. This is what they use mostly in West Africa, either a scorp or a large bent knife/hook knife with a handle that's long enough to use both arms.... it's not easy work either route you go.

The spiral pattern doesn't do much. Will will cut down the sustain a little... depending on how the drum is shaped now. I've seen a lot of those manufactured drums that have lathe marks on the inside to cut down the sustain. The size of the head in relation to the size of the sound hole in relation to the size of the bowl in relation to the length and width of the trumpet (bottom half), all effect the sustain more than the tiny bit irregular surface area that you create inside the bowl.

It doesn't have to be a spiral. The spiral is there because that's most efficient direction to hollow out wood. Going across the grain is hard and you have no leverage, going directly down can cause the the wood to splinter and tare.. so you carve it hollow by using a spiral. The sound waves produced by the djembe are too large to be effected by a little bit of carving inside the shell, however the air pressure inside the shell, and how it release when you hit the drum...and tension on the head have a lot to do with the sustain... and again this is determined more by shape/size.

Hope this helps... all that said... I'm builing a pro line of staved djembes now.. and I do carve a spiral pattern on the inside of the shell. For two reasons, it helps me round the shell after I glue up the slats, and because it does cut down a tiny bit on resonance

[davidognomo]

thanks, michi and trog

I had seen that photo at the show off your axe thread.

I'll let you know, but I don't know when it will be done, michi. This djembe has been deactivated for some years. I'm going to have to reduce the diameter of the rings (find a blacksmith, first). thanks for the image of the tools.

[davidognomo]

well...

seems that we were writing at the same time.
Thanks for all the info. I think I'll try to work a bit on the inside of the drum.

[drummingmangos]

I cant find a half round carving chisel anywhere, can someone help me find one? I have too many drums that ring and are super smooth on the inside. Reheading and reshaping the bearing edges is not doing any good. I would hope by roughing up the inside and carving a spiral will stop the ringing some.

[djembeweaver]

For the sake of research it would be great if you could skin it pre-carving, record the bass, tone and slap, then take the head off and do the spiral carving and re-record after to see exactly what difference (if any) it has made to the sound.

Probably a bit of extra hassle but nothing compared to the carving and it would be an interesting and unique opportunity to find out how it affects the sound.

[michi]

I cant find a half round carving chisel anywhere, can someone help me find one?

Have you tried Google? There should be plenty of online tool shops around. Amazon will probably have some.

Michi.

[drummingmangos]

Ok, I think im getting close. The addis curved gouge chisels are vintage and hard to find, There are plenty of straight gouges with straight handles but i would think it would be hard to get into some drums with. And there are only a few curved gouge chisels with bent handles all no cheaper then 60 bucks a piece. Im hoping to buy what i need the first time around, Maybe a straight gouge would work, or maybe a quarter round chisel?

Do you think this 25mm curved gouge would do the trick?

41HGC0GX52L__SL500_AA300_.jpg (7.35 KiB) Viewed 189 times

[EvanP]

Try Woodcraft. They have a few options that should work, some easier to use (the Scorp) than others (convex spokeshave) for this task.

http://www.woodcraft.com/Product/2004867/7518/Carvers-Spoon-Plane.aspx


http://www.woodcraft.com/Product/2001825/1305/pfeil-Swiss-made-Scorp.aspx


http://www.woodcraft.com/Product/2000562/25694/Spokeshave-Replacement-Blade-Half-Round.aspx

Nothbay Forge makes amazing carving tools, and their "bent knife" works very well for hollowing out in tight places.

http://www.northbayforge.com/bn.htm#maintarget

[the kid]

A proper tool shop, Dich Germany. Check the Adze, a proper tool.

http://www.mehr-als-werkzeug.de/categor ... 8_3692.htm

Drool

[EvanP]

Nice. Proper prices as well. North Bay Forge and Woodcraft havegreat adzes as well, but I'm not sure that would be my tool of choice for final finishing without a lot (years) of practice.