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post #1 of 19 Old 05-17-2009, 10:39 AM Thread Starter
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oops, live and learn

I was practicing some technique on a 14" platter the other day. I decided that the piece was thin enough and was starting to make my last past with a round nose scraper to take out any small imperfections in my gouge technique. Taking a very light pass, the platter suddenly "warped". I turned off the lathe and checked to make sure that it was still firmly planted in the chuck and it was. The platter had split from the edge to the centre. It was a little frustrating but it's okay because I learned to correct a lot of my poor lathe techniques. Basically, it was a great practice session and I learned a lot doing it. My question is this......what causes this type of breakage? Is it just something that happens to a piece? Nature of the beast? The wood is fully dried and it split along the grain. It was about 5/16" thick. I've heard of this happening to other turners from time to time but this is the first time that it has happened to me. Any thoughts?
Ken

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post #2 of 19 Old 05-17-2009, 11:59 AM
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Ken,

"Fully dried" does not always mean "fully stable". You might have a piece with slight tension wood characteristics and/or it might be lightly case hardened.

Paul

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post #3 of 19 Old 05-17-2009, 12:27 PM Thread Starter
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Ken,

"Fully dried" does not always mean "fully stable".
Good point Paul. I never thought of that. Thanks for the reply.
Ken

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post #4 of 19 Old 05-17-2009, 02:28 PM
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And the best thing about it Kenbo....you didn't get hurt!! I have heard about these things exploding and people getting hurt.

You had no indications of tension in the wood prior to the split?

Fred

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post #5 of 19 Old 05-17-2009, 07:25 PM Thread Starter
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There was no previous sign of instability whatsoever. Everything was fine and I wasn't turning at a very high rpm. It just seemed to go out of balance all of a sudden. When I checked, there was the crack. I had the full face shield on so at least my boyish good looks would have been protected. I don't work on the lathe without my mask. Had more than one large piece fly off and ricochet off the visor.
What would some signs of instability in the wood be? What are some of the symptoms that I should watch for? (is this too vague of a question?)
Ken

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post #6 of 19 Old 05-17-2009, 07:25 PM
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Wait a minute. Kenbo did something that didn't turn out right? I don't think so. This thread has obviously been started by an imposter.

Ken, I haven't started turning yet and have no good advice on that end, but I agree with the comments on possible wood stress (Though I don't know where you got the wood or what part of the tree it was). I ripped some boards out of a thick tree branch before I read about how branches are "stressed" wood. They're not quite air dried yet (about 18 months ago), but I'm thinking they ought to be loads of fun on the table saw.

I think I'll remove the splitter and blade guard and put my face up right in front of the cut, daring it to kick back.

Rob
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post #7 of 19 Old 05-17-2009, 07:33 PM Thread Starter
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Wait a minute. Kenbo did something that didn't turn out right? I don't think so. This thread has obviously been started by an imposter
Thanks for the vote of confidence Rob. What is it that is said......anyone can work with wood but only a true woodworker can hide his mistakes...(or maybe they just don't post them on the forum. )
Ken

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post #8 of 19 Old 05-17-2009, 08:34 PM
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anyone can work with wood but only a true woodworker can hide his mistakes...(or maybe they just don't post them on the forum. )
Ken

I've posted a few less than perfect projects here, and I've "forgotten'" to post a few, too.

Rob

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post #9 of 19 Old 05-18-2009, 10:59 AM
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Kenbo,
Do you have some pics you can post? Haven't had a piece just split like that without some kind of inducement from me. Curious to see what it looks like. Also, how did you have it chucked?
Mike Hawkins
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post #10 of 19 Old 05-18-2009, 03:33 PM Thread Starter
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Mike,
I've already gotten rid of the platter. I turned the bottom of the platter, leaving a tenon. From there, I chucked the tenon and turned the inside. The piece split with the grain. Amost like it had a weak spot in it. I could dig the pieces out of the burn pile, but I already broke the platter in half to make it fit in the pile better. This piece was laminated, but it didn't split on the lamination. It split along with the grain. Could the laminations have caused extra stress on the piece?
Ken

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post #11 of 19 Old 05-18-2009, 04:39 PM
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I don't think the laminations stressed the piece. Did one of the laminations have the grain running out through the piece. I've had pieces break because of that. If the grain looks like it runs across the the piece I am using for laminations I make the first cut on the bandsaw running parallel to the grain. Then I will make the next cuts on the table saw. This way I have the grain running the full length of the board.
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post #12 of 19 Old 05-18-2009, 06:08 PM
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OOPs live an learn

Sure glad ya didn't get klunked on the noggin.Heres whats left of a 14" ambrosia bowl that I WAS coring out last night.Had a full face shield on,an that sucker just exploded Thought about fixin it ,but ran outa tape
Ken
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post #13 of 19 Old 05-18-2009, 06:44 PM Thread Starter
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OK, mine wasn't that bad and I'm glad you weren't hurt. I was able to turn the lathe off before the crack turned into an explosion like that. Nice taping job by the way, I can barely see the cracks in the bowl.
Ken

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post #14 of 19 Old 05-18-2009, 07:45 PM
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Kenbo,
Sounds like John answered your question. It's kind of unusual for that to happen. I was thinking initially maybe you had turned a recess in the bottom and expanded your chuck into it. I have broke a couple like that by overtightening.
You can only tighten them till you hear a little 'tick', then you back it off a quarter turn.
BTW, what lake is that you are fishing on in your avatar pic?
Woodsman,
looks like nothin' a little CA glue couldn't fix. Did your coring tool bind up or something like that? Kind of a shame, looks like it was a nice piece of wood.
Mike Hawkins

Last edited by firehawkmph; 05-18-2009 at 07:47 PM. Reason: wanted to ask about the lake
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post #15 of 19 Old 05-18-2009, 09:53 PM Thread Starter
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Quote:
Originally Posted by firehawkmph View Post
BTW, what lake is that you are fishing on in your avatar pic?
I was on Smith's Bay which is in Wapoos, Ontario which is close to Picton. (fairly close to Sandbanks provincial park)
Ken
Thanks for the replies fellas. It was a curiosity thing as I don't have much experience in turning but am learning quickly.

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post #16 of 19 Old 05-19-2009, 09:37 AM
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OOPS,live an learn

Mike it didn't catch,but I was using the wrong blade on the coring tool and just cut to close to the bottom and it just let go.I felt it coming loose,but couldn't back the blade out quick enough.Yes it WOULD have ben a nice looking bowl.I'll post some pics off those ambrosia bowls when I get some of em done.
Ken W
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post #17 of 19 Old 05-19-2009, 07:10 PM
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Kenbo,
I looked on the map and it looks like you were fairly close to where we used to go on vacation. We used to go to Stony Lake, eleven years in a row. Great fishing, nice people. As a kid we always stayed on the Trent River near Cambellsford. Nice area you got there.
Mike Hawkins
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post #18 of 19 Old 05-19-2009, 10:09 PM Thread Starter
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I agree about the fishing Mike. Have caught some nice pike and bass in that bay. I'm hoping to get up there again soon and do some fishing. Haven't been up to the cottage yet this year. The backlog of work around here is unbelievable.
I dug out the platter that split on me this afternoon. I was looking at the profile of the split and it is about 5/16" thick EXCEPT in the centre where the tenon is. It looks like I took away a little too much material and it is only about 1/8" thick around the tenon. I wonder if the thinner wood at that point was enough to cause the warp/split? Can you tell that I am grasping at straws here?
Ken

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post #19 of 19 Old 05-19-2009, 11:45 PM
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Kenbo, as you said earlier the one good thing that comes from something like this is you definitely will look at the next one with a more critical eye and look to improve on several areas that could cause you a problem which will in turn create a better overall project. It truly is a case of live and learn!

Now on to the topic of fishing. I sure would love to head that way for some of those northern! Makes my mouth water thinking of a shore lunch!! Went to International Falls some years back and had one of the best times fishing I can remember.

John
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