Natural Edge Silver Maple Bowl

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Cwalker935

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This is natural edge bowl that I am working on. The bowl is made from silver maple and is 13” at its widest, 10” at its narrowest point and 7.25” tall at its highest point. I love natural edge bowls and silver maple is one of the better woods for this type of bowl.

I spent a lot of time sanding the bowl this morning which is kind of a mindless activity so I had a lot of time thinking about turning natural edge bowls and I decided to write a post describing the process for those of you that are not Bowl turners. Warning, this post is now on the nerd express so read further at the risk of being bored silly.

As many of you know turning is all about natural forces of a spinning object, the physical properties of wood, and tool control. First- the properties of wood. A straight piece of wood is like a bunch of strings laid together. It’s a lot easier to separate the strings then it is to tear the strings in half. To experience this take some of that white string cheese that we put in our kids lunches. First notice how easily you can separate the cheese lengthwise. Now try to tear a piece of string cheese in half, it’s much harder. Wood is just like that. When you are trying to cut a spinning piece of wood you are sometimes cutting with the strands and sometimes across the strands. Don’t try this with string cheese, putting a piece of string cheese on a lathe would probably create a huge mess.

When you push an object you are creating momentum, the force of the momentum is a function of how hard you push and the weight of the object. A hard push of a heavy object will have more force than a light push of a small object. That’s why an old fat guy like myself falls harder when pushed than a skinny little kid.

Spinning an object also creates momentum but unlike a straight push where the force is in one direction, the momentum of a spinning object is in the direction of the spin. Each point of the spinning object is being pushed in a different direction. A perfectly balanced spinning top stays in one spot since the force of each spinning point is equal and opposite to that of some other point so the forces balance each other out. If the top is not balanced it will move about or if the balance is really off the top will fall over. That’s why you should not try to spin an old unbalanced fat guy like myself, again I will hit the ground hard.

Applying all this to a natural edge bowl blank means you are dealing with a very unbalanced object that is stronger in places and weaker in others. Spinning this object results in differing levels of force all around the blank causing the blank to want to wobble. A heavy bolted down lathe with a strong chuck will minimize the wobble. I did not have my relatively light lathe bolted down until recently so my lathe had a tendency to dance around the shop. Needless to say it was hard to maintain good tool control as I was chasing the lathe around.

The relative strength of the wood (weak across the grain and strong with the grain) means that the wings of a natural edge bowl are flexing in and out since the spinning forces on the wings are not balanced. Additionally, your tool is coming in and out of contact with the wood. All of this is a recipe for disaster. If you are not careful, your tool tip will catch in the wood and result in any one of a number of bad things. These things include cutting a deep groove in your bowl, blowing your bowl apart, breaking your tool or tool rest, jerking your tool out of your hand, or all of the above. In short you have to be more than a little unbalanced in the head to want to turn a natural edge bowl.

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Charlie_W

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Awesome job on the bowl Cody!! And a great piece of silver maple too.
Well said write up!

.....and everyone please use your safety gear and stay out of the line of fire.
A remote kill switch for your lathe is a good idea in case something goes bad so you don’t have to reach around the spinning blank to turn the lathe off.
 

leehljp

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Feb 6, 2005
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Tunica, MS,
I have several silver maple pieces from my daughter's house. She had an 22"-24" tree cut last year and I have about 5 pieces 16 - 22 inches in diameter and 2 to 2 1/2 ft long. I sealed them but they are spalting as they sit in the log bin. I will give them a try later this summer.

I wondered about the "wobble" from the flexing.

Do you shape the outside or the inside first? (I have never had a mentor but just had to figure things out for myself, so I don't know what the proper procedure is - on bigger blocks.) My Grizzly lathe will take up to 16 inches (can go larger with out turning head, but the slowest speed only allows for about 16 inches.

Also, do you use a rubber ball of some sort or some sort of jam chuck in the tail stock during the process?

I enjoyed reading your post. Are you saying you can't turn silver maple down to 1/8" thickness? :biggrin:
 

Cwalker935

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May 18, 2014
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Thanks Charlie, Wayne, Mal and Hank.

Hank I usually shape the outside first and then hollow the inside, I work the upper part down to the desired thickness and gradually work down. I try to leave some bulk on the lower part of the bowl to help stabilize the upper portion while thinning. I did this bowl a little differently since it was really imbalanced. One wing was narrower and about an inch longer than the other wing. So I hollowed the center more than I normally would to try to get rid of some of the mass in an effort to reduce the imbalance. I left the wall about 1” thick while hollowing the center to around midway down. I then thinned the upper part to the final wall thickness and worked my way down. I left this bowl thicker than I normally like because of the differences in the wings and the amount of chatter I was getting, so you are correct it’s not 1/8” thick. I think you could turn a smaller and more balanced piece of silver maple down to 1/8”.

I use a “rubber chucky” jam chuck to clean up the bottom of the bowl.
 

OZturner

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From one "Old Fat Guy", to another" Old Fat Guy".
Cody, a Beautiful Natural Edge Winged Bowl,
and an Interesting , Informative Narrative, I enjoyed it Greatly.
These Bowls are always a challenge to turn, But you didn't elaborate about. the difficulty in keeping the Bark on the Now Narrow Section of the Bowl.
It is there that I have great Difficulty, that could be due to using wood from different species, or a deficiency in skills on my side.
I turn the Outside First, so that I can turn the Chuck Tennon for hollowing the Inside.
Congratulations and Thank you my Friend.
Brian.
 

Cwalker935

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Joined
May 18, 2014
Messages
2,975
Location
Richmond, Va
From one "Old Fat Guy", to another" Old Fat Guy".
Cody, a Beautiful Natural Edge Winged Bowl,
and an Interesting , Informative Narrative, I enjoyed it Greatly.
These Bowls are always a challenge to turn, But you didn't elaborate about. the difficulty in keeping the Bark on the Now Narrow Section of the Bowl.
It is there that I have great Difficulty, that could be due to using wood from different species, or a deficiency in skills on my side.
I turn the Outside First, so that I can turn the Chuck Tennon for hollowing the Inside.
Congratulations and Thank you my Friend.
Brian.
Brian,
After turning the outside l soak the bark edge with thin CA to help stabilize it. That often helps. I find some woods impossible to keep the bark on and other woods have to be harvested at the right time (when dormant) in order to keep the bark on. I have found silver maple to be more forgiving with respect to natural edge pieces.
 
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