Cracking Wooden Cylinder


I am making a wooden cylinder to be filled with lead shot to act as a weight for a grandfather clock. The first one I made cracked because I filled it with molten lead rather than lead shot. The wood eventually shrunk but the solid lead did not shrink resulting the crack. The next cylinder also cracked as I was turning it on the lathe... arrgh!
I make the cylinger from 4 inch squares of 4/4 wood with a 3 inch hole drilled in each. These squares are glued up in a stack and then turned on the lathe.
Question: Is it better to orient the squares with their grains at right angles to each other like plywood or will cross grain expansion cause more cracks? (The second one that cracked had the grains in line not crossed.)
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snipped-for-privacy@verizon.net wrote:

Parrallel grain is the way to go when laminating wood.
More work but much more elegant would be making it with staves like a barrel.
--

FF


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Molten lead? Yikes! I've used lead shot before as weights in various setups. Can't help you with your question, but it did get my attention.
My guess would be that it wouldn't matter, not with a 4" spread between grains. But then again, it probably does help - even if only a little - to alternate grains.
But doesn't a 3" hole in the 4" blocks narrow down the sides a bit too much? Only 1/2" diameter for that much weight sounds inherently risky.
Jack
snipped-for-privacy@verizon.net wrote:

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On 2 Oct 2005 17:35:31 -0700, snipped-for-privacy@verizon.net wrote:

That is inherently dangerous, and other adjectives I'll leave out. If you *must* make it from wood, then turn the solid piece and slow-drill later. Also, precut the solid piece on the TS to an octagon to have less to remove on the lathe. The drilled out center does not have to be dead-center, but you still have to be careful, and clamp the piece being drilled.
Question: How are you going to attach the piece to the chain?
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Guess who wrote:

In addition to what he said, I misunderstood the geometry. You should glue the blanks so that when you turn it the grain runs lengthwise, from the headstock to the tailstock, like a spindle turning instead of a bowl turning.
It would still be cool to build it out of staves like a barrel.
--

FF


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Wouldn't that be a pure end grain glue-up? That doesn't sound very sturdy.
bob
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Only if you do it wrong. Think about it.
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Doug Miller (alphageek at milmac dot com)
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I did. I don't get it.
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Glue up the block out of several pieces which are the desired length and width but less than the desired thickness. For example, if you wanted a cylinder 8" long and 3" in diameter, you'd glue up four pieces 3/4" x 3" by 8" to make a block 3" x 3" x 8", then put it on the lathe and turn a cylinder.
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Doug Miller (alphageek at milmac dot com)
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Doug Miller wrote:

Maybe BillyBob and I are picturing what is being turned a little differently than you are. I am picturing more of a disc, or squashed cylinder. Say, a 2.5" long cylinder with a diameter of 4".
-John
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Hello,
My 2 cents on the turning would be to do what was suggested above....if you're glueing...make a solid piece, turn it to size, and then drill out the diameter hole that you want. That will give you the support for the turning without having it blow apart on you.
What type of wood are you working with? Is it possible to get a piece big enough so that you don't have to glue it up?
Depending on your lathe set up, you could just turn it out on the lathe after you finish the outside diameter. From your description I'm guessing this is what you've been doing.....but....
Good luck
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Doesn't matter. You still glue it up out of pieces whose length matches the length of the cylinder, and whose width matches its diameter. There's no reason at all to ever need to glue end grain to end grain.
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Doug Miller (alphageek at milmac dot com)
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Thanks for the patient explanation. I was hung up on the explanation that the OP pre-drilled the pieces before glueing. I am not a turner so do not know all the tricks. How do you put the hole in it? On the lathe? I don't have a forstner bit that will go more 3" or so in depth. Actually I don't have a 3" forstner bit so its academic for me.
Bob
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Doesn't really matter. Most glues creep enough to allow for changes in RH. It's about 3:1 on change. Three percent RH one percent dimensional change. Not a lot with thin sides.
Easiest thing to do is laminate or use a large block lengthwise, where the distortion won't strain the glue line, just go a bit out of round. Lots of ways of doing this, from boring first and turning on tapered ends to hollowing on the lathe itself, or turning and boring the cylinder afterward. Any of the techniques used in box making (www.metacrawler.com) will work, if you have the equipment and skill.
I'd turn the cylinder, make ends and part them off, then hollow, but I have a chuck which will allow holding a piece by the end. Tougher to do between centers. There you'd be best to glue up your bottom after boring, and friction fit the top to get things trued and sanded, after boring out the center of the block now fitted with turned ends.
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On 2 Oct 2005 17:35:31 -0700, with neither quill nor qualm, snipped-for-privacy@verizon.net quickly quoth:

Cooper strips of wood, then use a poured round of lead with 1/4" of foam padding around it to accept any shrinkage. IOW, make your own barrels but don't worry about taper.
_ The strips will be shaped something like this. / \ (Half-ascii drawing to the left.)
--
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On 2 Oct 2005 17:35:31 -0700, snipped-for-privacy@verizon.net wrote:
The first one I made cracked because I

<<<<<< SNIP >>>>>>>>>>>>>>
Buy a 25# bag of #9 shot, pour it in cold. Molten lead in a wooden cylinder - yikes!
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wrote:

There you go. I was wondering why it had to be melted.
Bob
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