How Square is Your Square: A dial indicator method

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snipped-for-privacy@garagewoodworks.com wrote:

I bought a micrometer from Doug. When we measure, we don't food around! : )
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On Jan 3, 11:02 pm, snipped-for-privacy@garagewoodworks.com wrote:

3 x 5 index card = 0.004. Playing card = 0.012". Beer can stock = 0.015". Rolling paper (Job brand) = 0.001". and so on...
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wrote in message

Measure thousands of an inch between two lines. Sure it can be measured. Accurately? No. =============================================================================================Yes.
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wrote in message wrote:

read the article.
A minor caveat to this method is that it can be difficult to discern small gaps between the two pencil lines (especially with a thick pencil lead). The most you might be able to detect is a 0.010" difference which equates to a minimum detection of 0.036 degrees with an 8" square. Another caveat is that the edge you place your square against must be perfectly flat, otherwise you will not get an accurate calculation of your square's angle error. =============================================================================================================================================================Use a knife to mark and do it on a flat smooth surface. MDF or. better yet, a piece of metal covered in dykem blue. Make your line as light as possible. Use magnifier. A discrepancy of .001 is readily visible. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ The dial indicator method is 10X more accurate ==========================================================================================Got a metal lathe? If you do, it can be used to make a master square that is more accurate than anything you can buy for less than several hundred dollars. Not needed though. Use the flip and mark method.
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"Doug Miller" wrote:

---------------------------------------------------------------- Many on this list may not be old enough to remember the most useful of all formulas:
"If a Flying Red Horse can't spot the difference from a thousand feet, you're good to go".
Lew
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On Jan 3, 7:21 pm, snipped-for-privacy@garagewoodworks.com wrote:

4x dollar store reading glasses.
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snipped-for-privacy@garagewoodworks.com wrote:

square using a dial indicator. The method works in theory. I've tried it and it seems to work in practice. A caveat is that the square needs a thick edge to support a stylus.

Sinced/dx (arctan) is close to 1 near 0, yourerror is not very big, but your equation which divides an angle by L (before applying arctan) doesn't make sense. For instance, it suggests that if you choose L great enough that your error will be as small as you need it to be. I did not try to redo your derivations, but I am willing to do so if we don't find a concensus. By the way,you might sketch a triangle somewhere(tan = opp/adj)for those that may be a bit rusty at doing trig.
Bill
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Bill wrote:

I appreciate the point that you are trying to make, but I don't find the argument given to be as rigorous as it should be.
I'd enjoy seeing a re-write. I'll help here if you like. I don't think that L was "well-defined" (consistent) in the present argument Bill

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On Thursday, January 3, 2013 7:40:30 PM UTC-5, Bill wrote:

L is the length of the square's edge. It was defined adequately.
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I forgot to mention, what you have labeled as "References" are not references at all.
Please re-do.
Bill
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On Thursday, January 3, 2013 8:44:31 PM UTC-5, Bill wrote:

Yes they are. I am 'referring' to them in the article. It's done routinely in the literature. See 5d below where as it applies here.
ref·er·ence (rfr-ns, rfrns) n. 1. An act of referring: filed away the article for future reference. 2. a. Significance in a specified context: Her speeches have special reference to environmental policy. b. Meaning or denotation. 3. The state of being related or referred: with reference to; in reference to. 4. A mention of an occurrence or situation: made frequent references to her promotion. 5. a. A note in a publication referring the reader to another passage or source. b. The passage or source so referred to. c. A work frequently used as a source. d. A mark or footnote used to direct a reader elsewhere for additional information.

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snipped-for-privacy@garagewoodworks.com wrote:

References usally means bibliographical references (to related works).
"Notes" may be more appropriate (I'm not looking for an argument).
Bill

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On Thursday, January 3, 2013 9:05:34 PM UTC-5, Bill wrote:

Yes, usually. It is however, not incorrect how I used the term.

I like references. It's what I'm used to.

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snipped-for-privacy@garagewoodworks.com wrote:

When you submit your work for publication, the publisher will advise you in no uncertain terms how it it should appear. While your idea may be just fine, having reviewed a few books and papers before, it is my humble opinion your your paper needs work. I would look forward to seeing your ideas presented again. As has been suggested, this isn't rocket science, but the application of using the magnetic cubes to check for accuracy in squares is an interesting application. Why settle for good-enough.
Bill
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On Thursday, January 3, 2013 9:42:29 PM UTC-5, Bill wrote:

I've read more than my fair share of peer reviewed scientific publications. And as a scientist, I've written a few peer reviewed as well. I have never heard of a reviewer who had a problem with using 'References' in the fashion that I did.

You can't please everyone. Isn't that what they say?

Magnetic cubes?

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On 1/3/2013 6:40 PM, Bill wrote:

From what I've seen, Dr. Grella has a pretty good grasp of mathematics and scientific principles. ;)
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Swingman wrote:

Yes, there was just probably some confusion aboutnotation. I just don't think his present work is "camera-ready" yet, for publication. I think the work needsmorediagrams.
Thanks, Bill
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On Thursday, January 3, 2013 7:24:24 PM UTC-5, Bill wrote:

square using a dial indicator. The method works in theory. I've tried it and it seems to work in practice. A caveat is that the square needs a thick edge to support a stylus.

Trust me, the math works. Draw a few squares that are off by a little in CAD and check.
Use my online calculator: http://www.garagewoodworks.com/square_a_square_Math.php
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snipped-for-privacy@garagewoodworks.com wrote:

square using a dial indicator. The method works in theory. I've tried it and it seems to work in practice. A caveat is that the square needs a thick edge to support a stylus.

If you are going to present the math, then do so (properly).
The sentence tht you wrote: "The answer given will be the amount in degrees that your square is off. " is terrible. Squares are not "off", degrees are not measure in amounts, and no answer was given (and no question was asked)!!
If you are going to get rigorous, then do so--let's not pawn it off. "Trust Me, the math works", should not follow your (lack of a) a successful derivation. Lets not trip to slip the argument by people just because you figure you've already worked hard enough on it! I enjoy well-done mathematics as much as anybody, surely more than some. Hope to see you try again.
Bill

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On Thursday, January 3, 2013 8:04:12 PM UTC-5, Bill wrote:


Squares can be "off" in the sense that they are not a true 90 degrees. Every square will be "off" to some degree. Perfection is imaginary. :)

Reposted for your convenience: "For the same angle error, as L get longer so does abs(Delta1 - Delta2). "

There is no need to "try again" and I appreciate your veiled arrogance.
Where are you having trouble with the math?

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