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  #16  
Old 02-09-2017, 11:11 AM
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Bruce Sexauer Bruce Sexauer is offline
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When making a saddle I have been pretty reliable working on a stationary belt sander grinding to a specific thickness +/- .002 and getting that specific thickness everywhere. .001 remains elusive, however. I can reliably see the difference between .0100 and .0102.

Edited to say: Whoops, I did mean .100 and .102.
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Last edited by Bruce Sexauer; 02-15-2017 at 11:06 AM.
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  #17  
Old 02-09-2017, 11:49 AM
Frank Ford Frank Ford is offline
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Quote:
Originally Posted by Bruce Sexauer View Post
When making a saddle I have been pretty reliable working on a stationary belt sander grinding to a specific thickness +/- .002 and getting that specific thickness everywhere. .001 remains elusive, however. I can reliably see the difference between .0100 and .0102.
I hope you mean "0.100 and 0.102." If not, I'll be seriously envious!
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  #18  
Old 02-09-2017, 11:57 AM
murrmac123 murrmac123 is offline
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Originally Posted by Frank Ford View Post
I hope you mean "0.100 and 0.102." If not, I'll be seriously envious!
Good correction, Frank ...
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  #19  
Old 02-09-2017, 12:04 PM
Silly Moustache Silly Moustache is offline
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Many years ago, when the world was young(er) I was trained (at secondary school) in draughtsmanship and toolmaking.

(I got A level GCE ion both (few will understand that).

Whilst I didn't become an engineer or a draughtsman, I developed an "eye" and can gauge and name angles, see when something is square or not, and can show you a yard, a centimetre or a 64th of an inch by sight.

I can certainly tell the gauge of strings pretty well by sight/feel, and so I guess, if the OP chas daily practiced the skill I would tend to believe him.
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  #20  
Old 02-09-2017, 12:20 PM
murrmac123 murrmac123 is offline
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Originally Posted by Silly Moustache View Post
Whilst I didn't become an engineer or a draughtsman, I developed an "eye" and can gauge and name angles, see when something is square or not, and can show you a yard, a centimetre or a 64th of an inch by sight.
Andy, are you saying that you can look at an angle ...any angle ...and tell what that angle is just by sight ? To within what sort of tolerance ... half a degree ... two degrees ...five degrees ?

And to what degree of accuracy can you estimate a yard, purely by eye ?

I'm not doubting your abilities, just curious about your tolerances.
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  #21  
Old 02-09-2017, 12:41 PM
Howard Klepper Howard Klepper is offline
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Is that what they call "slut shaming?"
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  #22  
Old 02-09-2017, 02:46 PM
redir redir is offline
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Honestly for me measuring the nut heights or relieve under the strings with feeler gauges is impossible. I can't tell if I am placing the gauge sleeves in at an angle or if I am pushing the string up or what... But I can do it by eye and that's works for me too
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  #23  
Old 02-09-2017, 06:41 PM
mirwa mirwa is offline
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Originally Posted by Hot Vibrato View Post
I suppose I just need some solidarity here after essentially being accused of being a crackpot. Who else "estimates" to the thousandth of an inch, and for what tasks?
First, If I space two items apart one being 40 thou and the other 42 thou, I can tell with them side by side which is the greater gap, if I was to place these two items a meter apart I would not be able to distinguish which is the 42 thou.

I can guestimate with some accuracy 5 thou (plus or minus a thou), I believe, if I can guestimate 5 thou then others can guestimate way smaller with accuracy.

I personally could not guestimate something being 2 thou (with accuracy of half a thou), that is beyond my capability.

As a side note, I use to do a thing called NDT on aircraft, which is the detection and measurement of cracks to a thousand of an inch (plus or minus 1/10 thousand of an inch).

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  #24  
Old 02-09-2017, 07:36 PM
Truckjohn Truckjohn is offline
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Every single crusty old tool and die maker I known can spot 0.002" differences all day long.

The one that drove managers nuts is that most of them could make a calibrated tap with a hammer. The trouble was that the non-tool makers would see the crusty old fellow tap something with a hammer and think he could do it... And then the precision die parts would end up beat up with hammers... And the managers would have to go crack down like crazy.

"Why are you firing me for banging on this with a hammer? That tool maker does it all the time?"

"Well.. He knows how to do it and you wreck stuff....."
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  #25  
Old 02-14-2017, 11:13 PM
LouieAtienza LouieAtienza is offline
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Well, if I get a pack of extra light guitar strings, I can easily distinguish the .009" from the .011". Does that count?

Can also hum to within a few cents of A440, without hearing a reference note. Not as good as I used to, however.

Folks, our superhuman abilities are not to be discussed with mere mortals. With great power comes great responsibility. Not for showing off!
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  #26  
Old 02-15-2017, 05:43 AM
Hot Vibrato Hot Vibrato is offline
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Quote:
Originally Posted by LouieAtienza View Post
Well, if I get a pack of extra light guitar strings, I can easily distinguish the .009" from the .011". Does that count?

Can also hum to within a few cents of A440, without hearing a reference note. Not as good as I used to, however.

Folks, our superhuman abilities are not to be discussed with mere mortals. With great power comes great responsibility. Not for showing off!
Yeah, well I just sort of mentioned my superhuman abilities in passing. I imagine if Spiderman bragged about his abilities, he would likely get the same reaction that I did: "Oh, come on. Nobody can walk on walls..."

Yes. I think that distinguishing a .009" from a .011" (which almost anyone can do) is a perfect example of the ability of the human eye to distinguish a discrepancy of .002", and that totally counts.

I can tune a guitar to within a few cents of perfect without a tuner or any reference. I can hear in my head all of the notes of the open strings quite clearly, but if you asked me to hum a C#, I don't think I could do it*

*Edit: yes I can, but I have to hum a D first for reference, and then drop it a half step
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  #27  
Old 02-15-2017, 06:22 AM
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Heck, I can barely read this web page.
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  #28  
Old 02-15-2017, 11:13 AM
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Bruce Sexauer Bruce Sexauer is offline
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Quote:
Originally Posted by Hot Vibrato View Post
Yeah, well I just sort of mentioned my superhuman abilities in passing. I imagine if Spiderman bragged about his abilities, he would likely get the same reaction that I did: "Oh, come on. Nobody can walk on walls..."

Yes. I think that distinguishing a .009" from a .011" (which almost anyone can do) is a perfect example of the ability of the human eye to distinguish a discrepancy of .002", and that totally counts.

I can tune a guitar to within a few cents of perfect without a tuner or any reference. I can hear in my head all of the notes of the open strings quite clearly, but if you asked me to hum a C#, I don't think I could do it*

*Edit: yes I can, but I have to hum a D first for reference, and then drop it a half step
The trick I use for tuning a guitar to correct pitch is related to the last line in the quote. My ear knows what it sounds like to drop the E string to D. Once I make that sound, it is just a matter of then raising the pitch to E again. Some days this works better than others.

Love the calibrated hammer story, truckjohn.
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  #29  
Old 02-15-2017, 11:36 AM
Mr Fingers Mr Fingers is offline
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A lot depends on what it is that you're looking at. Something as seemingly simple as the rounding of a saddle top is hard for me to see when I hold the piece alone in my hand, but easy to see when I put it up against something flat, or just run a string across it. Particularly for parts that some of you have seen time and time again, such as string clearance over a fret, I absolutely believe that some of you (not me; I'm OK but not nearly as experienced as some of you!) can assess these dimensions. I once worked as a photographer doing color separations at a high end printing firm. We used meters and computers and every device available to process our images, but when it came time to move from camera to press, all films went to an old guy who had been processing color, professionally, for decades. He made minute adjustments using two incredible devices: his eyes and his brain. His experience and that neural network build up through years and years of scrutiny outperformed the mechanisms.
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  #30  
Old 02-15-2017, 06:12 PM
LSemmens LSemmens is offline
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I can hum to within a few Dollars of middle C, does that count?
Seriously, eye-balling a measurement is not something that I've really needed to do, so, if it's critical, I pull out the appropriate tool for the job. As for my tuning abilities, I should spend some time training my ear as I am rarely in the ball park if I do not have a reference point.
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