deep endgrain hollowing

[weisyboy]

i have been asked to make teh item below.

it is an african djembe drum. is it possable to make it in one peice or am i better to make it in 2 (bowl and vace) and join it?

wall thickness can be anyware from 20 to 40mm.

what kinda tool am i gunna need to hollow that deep (350mm) i asume id go from each end.

[Calm]

Good luck - i have no idea but Ern (Rsser) would be one i'd ask for sure.

What timber are you going to use?

Cheers

[weisyboy]

camphor.

[rsser]

Do a google on drum making and on deep hollowing.

There's lots of stuff out there and on threads on this forum.

[Jim Carroll]

Doing it as 2 peices and mortise and tenon the joint would be the easiest and using the woodcut proform with an extra handle would get the 350mm depth easily.

Camphor works easy so there shoule be no worries doing this.

You are basically doing 2 vases and you can go through the bottom to give you a guide for joining.

[jchappo]

This guy bored from each end:

YouTube - blairdavis 0308 10min

[Gil Jones]

I assume (as the drawing appears) that the drum will be hollow, and open through both ends (like most drums)?
Even at 650mm tall, the walls will be very thick and stable, so I reckon I would shape (and sand) the outside between centers, then form a tenon on the bottom (short) end, and with the aid of a steady rest, use an Oland type boring bar (with a 20mm to 25mm thick shaft) to clean out the 350 deep bowl. Then reverse it onto strong donut chuck to turn out the 300mm inner shape (carefully) in the donut chuck, and see if the steady rest could still be used. If the wood is wet, movement during the cuts could be troublesome, but Camphor is pretty stable (at least it is here).
If you have the Proform tool, as Jim said, that would be nice. Also, if you have a captured boring bar system you will have no troubles cutting.
The only reasons I am not for the two piece (mortise and tenon) assembly, is that it could dramatically change the expected sound (but then so could the relatively soft Camphor), and I would not be comfortable with the joint in a percussion instrument. But those reasons are just gut feelings for me, and are not based on facts or experience.
I will be very interested in seeing your progress, and the finished piece.

[RETIRED]

This guy bored from each end:

YouTube - blairdavis 0308 10min (http://www.youtube.com/watch?v=OgmWsGskKCU)My size turning.:D

[NeilS]

Hi Weisyboy

I spent some time thinking about this very same problem some time ago, but haven't actually fully implemented my thoughts as yet. So they are just ideas.

I have promise to turn my son a drum some time ago. He is a serious djembe drummer (just returned from a drumming workshop in Guinea). Not that he really needs another drum, but one turned by his dad seems to appeal to him.

Turning the drum in one piece is possible, but the issue there is getting a piece of wood that is sound enough to turn in one piece, not to mention the weight on the chuck that far out from the headstock. There is also the issue of what chucking you will use when you reverse the drum to turn from the other end. The small end is about 10" OD, and say 8" ID . The largest standard sized jaw is about 220mm in expansion mode from Vicmarc, and for that you will need one of their big chucks.. so over $400 set up cost. Unless you have them already, or convinced you will get enough other use from them, that's an issue, well at least for me.

I did turned a half-sized one for my grandson as a practice run and that went OK but that convinced me that I wouldn't tackle the full-sized drum as one piece. So I plan to turn the drum in at least two sections and tenon together, as Jim has also suggested.

Reasonably seasoned wood will be needed to overcome any warping before the sections are all mated and glued together.

Oland or hook tools would be the go for hollowing the end grain.

I will be interested to hear how you go.

Neil





The

[joe greiner]

It might be a good idea to turn the outside with some flat or hollow portions for the wheels of the steady rest to ride on, without adding longitudinal thrust tending to pull it out of the chuck while hollowing. After both ends are hollow, the piece could be remounted between centres (on plywood disks with mating grooves) to smooth away the wheel "platforms" to the final profile. This process should have only minimum tailstock pressure, so as to avoid compressive collapse at the juncture of the two shapes.

Cheers,
Joe

[Skew ChiDAMN!!]

My size turning.:D

Moving into miniatures, ? :D


A year or two ago I turned a staved tube about 700mm deep and 250mm outside dia.

The outside was easy, rounded between centres then held on a faceplate and a centre-steady, but turning the inside was a nightmare.

I used a homemade oland tool of about the same dimensions as Hughies "ripsnorter," although with only a 1/4" bit which, with an extension handle, managed the 350mm(ish) overhang with only minimal chatter (and when a 1" round bar starts chattering, there's no stopping it!) but, by the very design of an oland tool, was a right mongrel to get smooth straight sides.

Some old car-leaf spring were cut up to make L-shaped bits which'd fit the 1/4" hole but reach slightly past the LH side of the oland tool's shaft. They needed frequent sharpening, but allowed me to use the oland as a sort of bull-nosed scraper to true up the sides. (As I'm not a metal-worker and aren't tooled up for that sort of work, it was all a major headache.)

I'm certainly not in a hurry to make another one of those things... :rolleyes:

[hughie]

Hi Carl,

you could try a Ripsnorter...............:U

I go along with Gil on this point.

The only reasons I am not for the two piece (mortise and tenon) assembly, is that it could dramatically change the expected sound (but then so could the relatively soft Camphor), and I would not be comfortable with the joint in a percussion instrument. But those reasons are just gut feelings for me, and are not based on facts or experience.
I will be very interested in seeing your progress, and the finished piece.

Interesting video,loved the pneumatic clothes cleaner :D

[weisyboy]

and what is a ripsnorter and where do i get one

[joe greiner]

and what is a ripsnorter and where do i get one
Google is your friend, Carl. Add "woodturning" for better results.:wink:

Cheers,
Joe

[robutacion]

and what is a ripsnorter and where do i get one

What?:o Carl, Carl, Carl,...! where have you been?:D
Here,
http://www.woodworkforums.com.au/showthread.php?t=85943

Cheers:2tsup:
RBTCO

[NeilS]

Blair Davis has a very good solution going there, but again an expensive setup unless you are going to make a lot of deep drums or expect to do a lot of large diameter work requiring a steady. That steady that Blair is using looks like the US$950 model!

http://www.theokspindoctor.com/rest.html
I have been thinking about Hughie's reservation about the two piece construction method, which helps get around the expensive setup costs for just one or two drums. It seems that stave drum construction is considered by some to provide a reasonable acoustic quality, at least compared to laminated ply.

http://www.jtpercussion.com/
Whereas others claim that solid construction (again compared to laminated ply) is superior.

http://www.spiritdrums.com/snare/beat.html
So perhaps just one join, compared to 20 or so staves, should be OK.

Neil