Except we know the blade edge is not skewed to the direction of travel, so you will not have a skewed cut.
If your thesis is correct, you should have no trouble pointing out the errors in the many examples I've given.
Mike
[OP]
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Except we know the blade edge is not skewed to the direction of travel, so you will not have a skewed cut.
If your thesis is correct, you should have no trouble pointing out the errors in the many examples I've given.
Mike
Last edited by Mike Henderson; 07-26-2008 at 4:31 PM.
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In the lower right drawing, the blade is skewed. Direction of travel is forward, plane and wood in the same horizontal plane. Though it is small, it is a 4 degree skewed cutter. Therefor the cutter edge is skewed to the direction of travel--at 4 degrees.Originally Posted by Mike Henderson
Or have I misunderstood your statement above?
Mike
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Another 2 cents. The argument for angled ramp not being the same as the skewed blade this: the line of force is perpendicular to the blade's edge with a "skewed" ramp; with a skewed blade it is at some angle. In practical terms I think the very slight angle in the ramped shooting board is the more important factor -- skewed planes aren't made with a 4 degree skew. I am interested that Derek feels that the ramped version makes a better cut. Has anyone else used both types of shooting board? Sometimes the results defy the theory!
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As Randy said, the way you've drawn it, you would have a skewed cut because the blade edge is at an angle to the direction of travel. But that's not what's really happening. In the real world, the blade in the plane is at 90* to the direction of travel. You can't change that fact.
Randy's posting in #28 is the same position I hold.
Mike
Last edited by Mike Henderson; 07-26-2008 at 4:43 PM.
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Really?
Ok. Here's is the same plane with a 4 degree skewed cutter. The plane is moving forward on a ramp sloped upward in relation to the wood. The ramp is 4 degrees.
Is this a skewed cut?
It meets your and Mike's criteria of a skewed cutter and also challenges the statement that wood orientation doesn't matter--something you both have claimed.
Well, this has been a fun diversion from a really long work week. Only it doesn't accomplish a darn thing. So it's back to work for me.
Take care, Mike
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I'm not sure I understand the picture, but if the blade is skewed at an angle to the direction of travel of the plane, then it's a skew cut. If the blade edge is 90* to the direction of travel of the plane, then it's not a skew cut. The criteria is pretty straightforward.Really?
Ok. Here's is the same plane with a 4 degree skewed cutter. The plane is moving forward on a ramp sloped upward in relation to the wood. The ramp is 4 degrees.
Is this a skewed cut?
It meets your and Mike's criteria of a skewed cutter and also challenges the statement that wood orientation doesn't matter--something you both have claimed.
Well, this has been a fun diversion from a really long work week. Only it doesn't accomplish a darn thing. So it's back to work for me.
Take care, Mike
The position of the wood is immaterial.
Mike
Last edited by Mike Henderson; 07-26-2008 at 5:13 PM.
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In order to do what you ask, I cann't start by assuming your definition of a skew cut is correct. If I do, it's a tautology and there's no point in debate. I agree that it's one way of achieving a skew cut, but not the only way. If you can support your current definition, great. Just post your source(s) and I'll read them with an open mind.
In the meantime, here's Hack's take on skewing a cut. Before going any further, please let me know if you agree with it or not.
http://books.google.ca/books?id=Zq2M...um=2&ct=result
If you have other resources you'd like me to see, please let me know.
Thanks.
GR
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Contributor
The pictures seem to agree with what I've been saying. If you do not agree with the definition I gave, what definition would you use?
Let me suggest that you just state your thesis rather than asking me questions. If there are assumptions you need to make, state the assumptions and proceed from there.
Mike
Leonard Lee has a discussion of skewing in his book "The Complete Guide to Sharpening" - his discussion agrees with what I've been posting.
Last edited by Mike Henderson; 07-26-2008 at 6:09 PM.
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I'm using the definition I've mentioned to in two previous posts. Here's the gist:
"I feel skewing occurs when the blade edge and wood are configured to achieve the following outcomes:
* More of the plane blade is cutting the same width of wood (due to the tilt); and
* The effective pitch of the blade is lowered.
I think these outcomes accurately define "skew" and, as Mike W said, can be the result of many configurations between plane blade and board."
Do you disagree with anything in that statement? Also, would you mind restating your definition so there's no confusion.
I have Leonard Lee's book in front of me. There's lots on skew cuts in Chapter 2. I too feel that what he says is consistent with my definition of skew cutting. However, I can't find anything that restricts it as narrowly as you have previously defined it. Maybe I missed it. Please point me to the passage and I'll read it right away.
Thanks.
GR
[OP]
Contributor
My definition is that there is no skewing when the blade edge is at an angle of 90* to the motion of the plane.
If you can demonstrate skewing in that situation, I'd appreciate your explanation.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
I imagine many here have Leonard Lee's book. So if you look at page 10, in the upper right, it shows a comparison between a straight and skew cut.
Notice how it demonstrates this comparison with a circle (standing in for a single fiber). A circle is rotation invariant, so no matter how you rotate the image, the skew and straight cut comparison will remain.
Now bundle a bunch of those circle fibers together and you have the end grain of the board. Since each single fiber is invariant to rotation, then the sum of those fibers are also rotation invariant since cutting is a linear operation (pun intended for those math geeks out there).
The conclusion being that the orientation of the board has no bearing on skew vs straight since the cut is defined as the orientation of the cutting edge to a single, circular, rotation-invariant fiber.
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Hi Ganthan,
I visualized this, and then double-checked it for real on my ramped shooting board -- that is exactly what is going on.
-Andy
Member
That is not a definition, Mike.(That's the same as saying your definition is that a ramped shooting board can't make a skew cut). I disagree with your definition, but that's how this all got started. I can't find any support for it and it doesn't seem you can provide any either. It seems it's just your opinion and I respect that.
However, if you agree with my definition of a skew cut, I can prove that a ramped shooting board creates one, albiet small.
GR
Member
That's been my experience, Andy. Plus the effective pitch of the blade is lowered. That's a bit harder to visualize, but Lord help me (and everyone) if I have to draw a picture.
GR
More blade is cutting because you are essentially going from corner to corner which gives a larger cross section. But each individual fiber is still being cut at 90 degrees to the iron.
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