Mounting a 13" diameter by 13" deep stave cylinder to turn the inside.

[Larry Litwin]

First, my lathe is a Nova 2000 with a 16" swing so I have to work within that restriction. It does have a swivel head but ...

Originally I was going to make the cylinder 18" deep but thought 13" might be less of a problem.

I've got cole jaws with extensions and can make a plate to press against the tailstock side to turn the outside smooth. I suppose I might be able to make a ring and attach it with long threaded rods to the cole extensions - similar to a donut. Is there another way that would fix/hold the tailstock end of the cylinder that I could buy or build that would allow me to turn the inside to a consistant thickness? I know it's a long way off the toolrest but I could do one end (say top) and then reverse it and do the other (bottom). That way I'd only be working a few inches off the toolrest - I have a toolrest that can extend partway into the cylinder.

[Patrick Morris IV]

Steady rest is what I use when turning stave construction items.

[Jim Morgan]

You want to turn a hollow, open cylinder, right?

When turning that far from the headstock, standard Cole jaws will not hold. You can improve them a bit by replacing the buttons with countersunk bolts - run them through a nut or two before screwing into the jaws so the head stands proud, then tighten the jaws so the corners of the screws bite into the work. I'd start with that in conjunction with a steady rest (a Nicol-style steady rest would work best), true up the opposite end & glue on a block that you can attach to a steady rest. Solid stock is best for the glue block. Flip it around and work the inside of the half towards the tailstock, always using the steady to supplement the glue block. True up the tailstock end, glue on another block, flip it around again, part off the first glue block and Bob's your uncle.

[Larry Litwin]

Sorry if I didn't give enough information. Yes it is a cylinder open at both ends - OD 13" with wall thickness 3/8" but would prefer to get it down to 1/4". I'll mill the staves from mahagony block - 3 3/4" thick 18" wide 32" long. 12 staves 13" long 3/4" thick. It's for a concert tom 13" by 13". More than 12 staves (so I could use thinner stock) would be too hard to glue up.

To do the outside I can put a tapered plug on a faceplate at the headstock end and a plug with the livecenter pressing it against the headstock. Turning the outside should be easy.

The drum hardware for the tensioning bolts (six of them) is mounted with two bolts through the cylinder. If I made a circle that fit inside I could screw it tight through those holes and use a rod to pull it tight against the headstock. I'm not sure that would be enough so a steady rest would likely be essential. And it would still leave a ring where the bolts attach.

I looked at steady rests with a 16" swing and they cost about $600. I don't have the skill, materials, or machinery to make a Nicol-style steady rest. Even with a steady rest I'd also need something to push (pull) the cylinder into the headstock mounting.

Maybe the easiest mount would be a 14" disk screwed to a faceplate (probably sturdier than cole jaws) with a tapered plug disk glued to it that fits the cylinder on the headstock end. Same type disk plug pushed by the livecenter on the tailstock end. Once the outside is done I could replace the livecenter disk with a ring - 13" ID and 14" OD and use threaded rods to pull the disk on the headstock and the ring on the tailstock tight. Do half the inside, remount, do the other half.

New question - am I nuts or could this work?

[Edward Weber]

What you're describing is a large donut chuck and it will work just fine.

[Jim Morgan]

Sorry, I meant to say, "glue on a block that you can attach to a faceplate."

Will the cylinder be slightly convex across its length? That would give something for the outer ring of your donut chuck to clamp down on.

[Edward Weber]

Sorry, I meant to say, "glue on a block that you can attach to a faceplate."

Will the cylinder be slightly convex across its length? That would give something for the outer ring of your donut chuck to clamp down on.

If not, temporarily glue some stops to the outside to give the clamp something to register on.

[Larry Litwin]

Thanks to everyone. Very helpful. (somehow I keep losing this post - posted it yesterday & today not there and just lost it again).

I'm going to attempt the large donut chuck. I'll post how that works out. I'm in the middle of a project and won't get to the drum for a couple weeks. I wanted to get an idea how to do this and use the between time to pick up what I need - threaded rod, nuts, washers, etc.

Once again thanks to everyone.

[Larry Litwin]

The question has become moot. As I always do, when starting something I've not done before, I thought through the process and tried it out in pine first. Rather than make a 13" deep cylinder, I made it shallower to save wood. Everything went fine. I even got the 15° angle on the staves perfect the first try (with a Wixey). After turning the outside to 13", I took it off the lathe and gave it a slight squeeze to see if it flexed at all. It did not - it shatered into many pieces.

So ... It's too much work to take a chance that a deep cylinder would hold together. Instead I bought an unfinished drum shell.

[Jim Morgan]

The question has become moot. As I always do, when starting something I've not done before, I thought through the process and tried it out in pine first. Rather than make a 13" deep cylinder, I made it shallower to save wood. Everything went fine. I even got the 15° angle on the staves perfect the first try (with a Wixey). After turning the outside to 13", I took it off the lathe and gave it a slight squeeze to see if it flexed at all. It did not - it shatered into many pieces.

So ... It's too much work to take a chance that a deep cylinder would hold together. Instead I bought an unfinished drum shell.

Sorry to hear this. Generally with stave construction there is plenty of long-grain to long-grain gluing surface. If you want to attempt this again some time, I am sure that we can help you debug your gluing process.

[Larry Litwin]

I appreciate the offer. I think the gluing was likely OK - I've done a lot of segmented bowls and they've all held up - even the practice pieces which stay in my workshop that has a huge cold to hot change over a short time in the winter (ambient to 80°-90°F in an hour). I could build a segmented cylinder to get a lot of long grain to long grain but didn't want all that glue (let alone the way it would look). Have no idea how that would affect the sound.

I think part of the problem was the test "cylinder" was only 1.75" deep. So not a lot of glueline to begin with. Then when I turned it down to `13" diameter it was 1/4" or less thick at the joint. Had I used 1" stock instead of 3/4" and made sure the joints were completely internal and a full 3/8" and the staves were 13" long and maybe splined the joints ... maybe/probably it would have held up. But too much work for a probably. It was so much easier to buy a proper unfinished drum shell and just get on with it.