Am I doing this backwards? - Woodworking Talk - Woodworkers Forum
 
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post #1 of 15 Old 01-17-2011, 09:10 PM Thread Starter
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Am I doing this backwards?

I just finished a desk I've been working on and decided to get back to the lathe with bowl number two. It was another little ash bowl that was roughed out in July and has been sitting in a can of sawdust since. It held up well.

Anyway, I put the tenon in the chuck and evened the sides of the bowl before going inside. I got the walls down to where I wanted them and things were going well. Then I turned it around and put it in the jumbo jaws to finish the bottom.

Crack! I heard it but I couldn't see it anywhere, so I just backed off the tension a little and got to work. It blew up about 30 seconds later. I'll bet you guys saw that coming.

Should I be putting it in the jumbo jaws first while the sides are thick and can handle it? But if I do that, how do I avoid chuck marks on the tenon on the bottom?

Thanks,
Rob
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post #2 of 15 Old 01-17-2011, 10:38 PM
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You are not doing it backwards, but that was really thin to reverse on a chuck. You have to be very gentle when chucking something like that (might work if the tail-stock pressed the piece against chuck). I would have used a friction chuck to finish the bottom. Try chucking up a short piece of 1-1/2" pvc pipe; turn the free end flat with soft corners. Then use the tail-stock to hold your bowl against that with a thin pad of paper towel or shelf liner between the bowl and the pipe. Then you can turn the bottom except for a nub where the tail-stock is, carve the nub away off the lathe.
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post #3 of 15 Old 01-17-2011, 10:39 PM
4Woodturning
 
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you did all the steps right, I have seen a lot of bowls become air borne due to, dull tools, too heavy of cuts, compressed when you have been expanded jumbo jaws(depends of the rim of the bowl). might want to leave the tail stock forward for support while working on the outer part of the foot working towards center, once down to a little nub remove tail stock take out the nub with light cuts. and might not want to loosing up the jaws after being tighten, to much muscle? you get the feel for it. hope you was wearing a face shield and wasn't hurt.

Jeff,

"Just because your not bleeding, don't mean your turning safely"..
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post #4 of 15 Old 01-17-2011, 11:26 PM
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+1 on a jamb chuck if the walls are that thin. It should not take too much to put it onto one. If you want to bolster the hold some carpet tape will help.
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post #5 of 15 Old 01-17-2011, 11:58 PM
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If you are dead set on using the jumbo jaws, then I have to agree with jeff, the tailstock would be the way to go. You just barely need enough grip on the jaws to hold the bowl in place. Plus the small amount of pressure from the tailstock, and you should be able to take small cuts, and have success. And jamb chucks are great as well. Imo, jamb chucks are easy, and probably the safest method I've run across, if you want to turn the very bottom. I carve mine off with an angle grinder, and a palm sander to even it out, and it takes about the same amount of time, i guess.
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post #6 of 15 Old 01-18-2011, 10:56 AM
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an angle grinder??? 0.o
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post #7 of 15 Old 01-18-2011, 02:38 PM
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That's just one of the reasons I don't use the Jumbo jaws. Since I start my bowls between centers there is always (well OK 95% of the time) a small tenon with the original mark left from my tailstock on the bottom of the bowl. I simply put a piece of rubber over my chuck and pull up the tailstock and turn the bottom and then reduce the size of the small tenon until I get nervous. Then I carve this away.
Doing it this way you are never touching the outer edge of the bowl and have a lot more strength. Even when I use my vacuum chuck I use a smaller chuck that fits inside the bowl.
I think I posted this earlier but not sure it was on this site. It is an article I wrote for our club on different ways to reverse turn a bowl. Look it over and see if something will work for you.
http://www.cumberlandwoodturners.com/htm/tips.htm
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post #8 of 15 Old 01-18-2011, 03:25 PM
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Yeah, my recesses, or tenons are usually pretty large, so there's a lot of meat to take off. But I usually work between the 10" and 15" bowl sizes. For the really thick ones, I'll use a lancelot disk on my angle grinder first, followed by a 36 grit sanding pad on another angle grinder. by then, it's just the palm sander to even it all out really quick and put a really good surface on the whole area. I know it sounds like a lot, but it's just a few minutes in reality.
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post #9 of 15 Old 01-18-2011, 05:08 PM
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every body has there way of doing things you have to figure out your way which has the highest sucsess rate and dont worry about mistakes because if you dont have any then you are not working enough
I myself have a pile of fire wood in the corner of my workshop lol
just keep working mate

Old wood workers never die thay just get dry rot
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post #10 of 15 Old 01-18-2011, 06:54 PM
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Am I doing this backwards

I use the jumbo jaws quite a bit,but like said I run the tail stock up against the bottom,but I have small wooden washers that I use between the tail stock and the piece to keep from making that little hole in the bottom,that way I can clean the bottom up to about a 1/2' then slice the nib off with a sharp chisel,then sand it off my power sander with about a 2" sanding disc.

God Bless all
Ken Ward
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post #11 of 15 Old 01-18-2011, 07:14 PM
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Rock,
Whenever you hear that telltale click, lookout, cuz she's gonna blow. I use jumbo jaws without the tail stock, but mine has square-shaped rubber dovetails to hold the bowl. Very light pressure when I tighten it up. Extremely light cuts with a freshly sharpened tool. The tailstock support is a good idea. I would take a dremel tool with the little sanding drum and soften up your broken edge just enough to round it over. I think it would look pretty neat and make a great conversation piece.
Mike Hawkins
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post #12 of 15 Old 01-18-2011, 08:27 PM Thread Starter
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Wow, guys, good stuff. I learned a lot from those responses and have a good idea about how to approach the next one. It makes good sense to use the tail stock to lessen the necessary pressure and I may try that, but I also like the other chucking methods mentioned. I'll experiment.


Quote:
Originally Posted by firehawkmph View Post
I would take a dremel tool with the little sanding drum and soften up your broken edge just enough to round it over. I think it would look pretty neat and make a great conversation piece.
Mike Hawkins
That's a cool idea! I'm going to do that. Even though it was broken, I hated the thought of throwing it in the wood stove.

Rob
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post #13 of 15 Old 01-18-2011, 09:44 PM
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It's not broken, we call that a redesign. Post some pics when you get it done.
Mike Hawkins
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post #14 of 15 Old 01-20-2011, 09:04 PM Thread Starter
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Quote:
Originally Posted by firehawkmph View Post
It's not broken, we call that a redesign. Post some pics when you get it done.
Mike Hawkins
One redesigned bowl with a few coats of Formby's Tung Oil Finish. Think I'll keep paper clips in it at work. Thanks again for the idea.

Rob
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post #15 of 15 Old 01-20-2011, 10:37 PM
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Guess that's what that piece of wood wanted to be.

Tim
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