Wondering Why

charlieb · 2007-05-20T03:43:23+00:00

I tend more towards turning smaller stuff, sometimes really small stuff - maybe it's because the JET mini/midi isn't made for doing BIG stuff. My tool of choice is a curved edge skew either 1/2" or 3/4". Because I want to get into tight places - deep narrow V cut, small 5/8 spheres, a vertical wall that a sphere butts up against, I find the 30 degree interior angle of the skew limits what I want to do. So I sometime get one of my bench chisels and with it's single bevel, I can make the cut I want. Should probably just break down and get a bedan. But it got me asking "Why can't the interior angle go to 20 degrees?" If the 30 degree interior angle is a general purpose angle and erring on the size of caution when it comes to the size of the chunk of wood, why can a tighter angle be used for smaller stuff. For a given rpm, the force on the edge goes up with the diameter AND the mass of the rotating piece of wood. And with smaller turnings you start with smaller square blanks rather than a very asymetric tree trunk with knots, some not apparent 'til you get into it a bit. With a sqaure blank the edge is initially contacting wood 4 times per revolution whereas with a "tree trunk" type of starting point, it may only contact the wood once per revolution. So what say you regarding a 20 degree interior angle on a 1/2" skew? Good idea? Bad idea? Something to try - taking some extra safety precautions (face shield, mouth piece, chest protector - cup - and a phone handy with 911 on speed dial)? charlie b who sometimes spends too much time wondering and not enough time on The Wood

Wondering Why

May 20, 2007 23 Replies

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Arch 19 years ago

Hi Leo,

11.) "That's a good idea, but the development costs and future sales don't meet our profit plan, but thanks for coming by". Only to see a variation marketed later. This happened to me (not in the turning business) and I started my own small R&D company: Medical Measurements. Soon found out that large manufacturers know that a patent is just a hunting license and is usually too expensive to defend. Sometimes it's better to join them than oppose them so my little company is long lost somewhere in Johnson & Johnson. :)

Turn to Safety, Arch Fortiter

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charlieb 19 years ago

Don't think so. Looking from above . . / \ vs /| / \ / | 30 degrees 15

Note that the single bevel will get into tighter spots (ie deeper cuts with steeper side walls)

From the side they'd look identical - from one side

+-+------------- +-+------------- \ \ \ \ +-+----------- +-+-----------

but from the other side +-+------------- +-------------- \ \ \ +-+----------- +------------

charlie b

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Mike Burr 19 years ago

Well, With the Sorby Spindle Master it is an extension of the shaft with a highly polished bevel on one side. I have to admit I use mine a lot more than I use my skew for doing taper work and making well defined rounds with a good flat surface below it. But that's just my 2 cents worth,

Mike

Waiting to graduate from the first 20 year career and move onto the second.

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Leo Lichtman 19 years ago

^^^^^^^^^^^^^^^^^^^ "Other things being equal" means the total included angle on both tools would be the same.

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