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TOPIC: Does your angle cube reading match your W.E ?

Re: Does your angle cube reading match your W.E ? 1 year 4 months ago #10557

  • EatingPie
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Geocyclist wrote:
One thing I found makes a difference is to make sure the stone is placed exactly in the same place every time. I line it up even with the edge of the vice. Second, I try to be consistent with how it sits against the blade. I noticed (even more so with strops which are soft) that a very small rocking motion changes the angle. Depending on the knife you have a perfectly straight edge or some curve. I also make sure the gage is "straight" on the stone.

To check the quality/repeatability of your angle gage use something solid, like the kitchen counter top. Place the gage (same spot), remove, turn it 90 degrees, place it back. If you can get repeatable readings here that's as good as it gets, anything less on the WE is probably user variability in how/where it is placed.

My final 2 cents. The diamonds are pretty consistent. Once you set it you are good to go. When changing to other stones or strops, you can also check again with a marker to make sure all is good.
All great advice! I noticed all this pretty early on. The meter is sensitive to pitch and yaw both, so if it's not set the same every time, it's inconsistent. I do almost exactly the same as you (which, of course, is why your advice is great and -- I might add -- you're brilliant too! :D).

The gauge seems to be most accurate when the plane of the face is exactly perpendicular to the base (alternatively, the corners should all be parallel to the base).

This makes it a nightmare to measure the forward bevel of Tanto knives. In that case I put the meter on the stone and set it against the bevel. Then, I turn the gauge until the face is perpendicular, using a stone set vertically on the base as a guide. It's not super accurate, and I just use this to get a ballpark angle the first time I align the knife in the vice.

Sounding more and more like I'm on par with experience. Always good to know! :)

(This sort of raises the question of "how accurate is accurate?" but that's probably for another day and another thread!)

-Pie
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Re: Does your angle cube reading match your W.E ? 1 year 4 months ago #10561

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EatingPie wrote:
Rather than start a thread, I thought I'd revive a revival...

My angle cube tells me a different angle almost every time I lay the stone against the bevel. I mean, even if I just lift the stone and re-set a second later, I get a slightly different reading. For example, I will see like 25.2 then 25.4, then 25.2, then 25.3, etc. I know the accuracy is +/ 0.1 degree, but is this how it should really behave? And I am holding the stone at the exact same spot every time, so it's not variance on my part.

-Pie
For an idea of the capability of the Angle Cube, you could try this older thread. It looks at the accuracy (yep, it is) and precision (yes, it has some) in a semi-rigorous test.
wickededgeusa.com/index.php?option=com_k...id=363&Itemid=63#363
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Re: Does your angle cube reading match your W.E ? 1 year 4 months ago #10562

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EatingPie wrote:
....(This sort of raises the question of "how accurate is accurate?" but that's probably for another day and another thread!)
-Pie
Bah. Easy Peasy. Why wait.
Always know that accuracy is a qualitative term, not quantitative. So, very accurate, quite accurate, good-enough-for-government-work accurate, and this-thing-ain't-worth-a-crap-because-every-time-I-lay-it-up-against-my-knife-it-changes accurate and so forth are all accuracy statements. Period. No numbers required.
Precision, error, repeatability and reproducibility, on the other hand, are all quantitative terms and are expressed numerically.
So the question we really want to ask is: "How much error can I tolerate?"
See? Easy Peasy.
:silly:
Last Edit: 1 year 4 months ago by dgriff.
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Re: Does your angle cube reading match your W.E ? 1 year 4 months ago #10566

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dgriff wrote:
For an idea of the capability of the Angle Cube, you could try this older thread. It looks at the accuracy (yep, it is) and precision (yes, it has some) in a semi-rigorous test.
wickededgeusa.com/index.php?option=com_k...id=363&Itemid=63#363
Oh, wow! Good thread! Maybe I resurrected the wrong one! :)

I noticed the statement: No measurement exceeded 0.1° deviation from the reference angle. That means that every measurement was at most .1° degree off? I commonly seeing readings of.3° difference (in terms of your second post, maybe I could call this "accurate but out of spec!").

I also noticed another statement: The display did not always reach stability right away. Sometimes as much as 15 seconds were needed, but generally 5 or so seconds was enough. I usually wait a few seconds, but seldom 5, and certainly never 15! I'll give the cube another shot in Patience Mode and see how it works. B)

Thanks for both the link and for all your work on verification!

-Pie
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Re: Does your angle cube reading match your W.E ? 1 year 4 months ago #10573

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EatingPie wrote:

The gauge seems to be most accurate when the plane of the face is exactly perpendicular to the base (alternatively, the corners should all be parallel to the base).

-Pie

I keep a square nearby for those rare instances when I'm really worried about extreme accuracy. I set one side of the square on the base and the other against the cube to ensure it's vertical from front to back. I align the edge of the cube to the edge of the stone when I attach it. I also hold the stone against the knife with my opposite hand, reaching around the vise and pulling the stone into the blade with thumb and middle finger.
--Clay Allison
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Re: Does your angle cube reading match your W.E ? 11 months 1 week ago #14052

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dgriff wrote:
EatingPie wrote:
....(This sort of raises the question of "how accurate is accurate?" but that's probably for another day and another thread!)
-Pie
Bah. Easy Peasy. Why wait.
Always know that accuracy is a qualitative term, not quantitative. So, very accurate, quite accurate, good-enough-for-government-work accurate, and this-thing-ain't-worth-a-crap-because-every-time-I-lay-it-up-against-my-knife-it-changes accurate and so forth are all accuracy statements. Period. No numbers required.
Precision, error, repeatability and reproducibility, on the other hand, are all quantitative terms and are expressed numerically.
So the question we really want to ask is: "How much error can I tolerate?"
See? Easy Peasy.
:silly:

Accuracy is a qualitative term when used in that manor, but it is not by definition a qualitative term. Accuracy is a quantitative term when described properly. Accuracy refers to how close a quantity (measurement, count, etc.) is to it's true value and it can be expressed numerically just as precision, error, repeatability and reproducibility. For instance if a thing is known to be 10 units in length and I measure it to be 11 units my accuracy is 11-10= 1 units when expressed with absolute deviation. I could also express the same accuracy in relative deviation by stating that my accuracy is (11-10)/(10)=0.1 or 1% relative deviation. There are two problems at work here, the first and most fundamental problem is that often times the true value is not known. The second problem is how the terms are used. Many people don't fully understand the terms and miss use them frequently.

An easy way to test the accuracy of your angle cube is to attach the cube to a bubble level and align the level in a horizontal or vertical position using the levels bubble. The cube should then be zeroed and the orientation of the level changed by 90 degrees(aligned again with the bubble). Any deviation from 90 (or the divisions of 90 depending on orientation of the cube) displayed on the cube can be used to describe the angle cubes accuracy. However, there are some problems with this method that lead to error. Mainly being the accuracy and precision of the level itself. Doesn't do much good to compute the accuracy of a tool if your aren't actually comparing it to the "true" value. I'm not sure how accurate a bubble level really is but, my guess is that its pretty good (coming full circle with the qualitative use here..lol) and if used correctly should be good enough (see how easy it is to qualitatively describe accuracy) for testing an angle cube.

To test the precision just simply place the cube in the same exact spot repeatably and note the different readings. Again there are some problems with this method that lead to error but, that's another lengthy discussion about repeatability and a whole other mess of errors that go way beyond what is needed here.
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Re: Does your angle cube reading match your W.E ? 11 months 1 week ago #14064

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Well, I remember quite well this post. I'd pulled the cork on a bottle and was feeling a little loose and lippy--clearly I hadn't pulled enough corks....
Since you've elected to dredge it up (things better left unsaid...let sleeping dogs lie...quiet, you'll wake my dad...), I suppose I'll have to give it a go with full faculties.
In its common non-technical usage, accuracy usually means 'how well will this thing tell me what I want to know'. In the more technical setting, it is usually associated with a value range (tolerance; specification) that represents how well the user can expect the instrument/tool to display the expected, or true, value. Since the true value cannot be known, error (or accuracy, if you will) cannot be known, only estimated, hence the '±value' for a symetric specification.
Now to the crux of it. By definition, accuracy is a qualitative indication of the ability of a measuring instrument to give responses close to the true value of the parameter being measured (ref. VIM, International vocabulary of basic and general terms in metrology, para. 5.18; also The Metrology Handbook, 2nd Ed., Jay Bucher PhD, Editor, ASQ Quality Press 2012, pg. 470), and many more. No matter how it is used, accuracy is a metrological term, and thus defined in metrological terms. :)

Also, see the link above in post 10561 for a look at an Angle Cube test.

Cheers
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Does your angle cube reading match your W.E ? 11 months 1 week ago #14067

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There are several definitions out there of the word and times when the true value can be known or accepted as true but, as you say it may be best to just let sleeping dogs lie. Didn't realize this thread was so old, was doing some research into the angle cube and considering my options when I found this thread. :silly:

The Angle cube test is definitely interesting. I would have expected it to push the limits of their published specs a little more than what you found.
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