Eyeballing to the thousandth of an inch

[mirwa]

A difference exists in comparative assessment and general guesstimate.

If you have a thin string, you know approximately what it is before touching, one can guesstimate quite easily which gauge of string has been used.

Guesstimate a gap between a fret and string is another example of comparative assessment, we know frets range in the 30-50 thou crown height, we know the string going over the top is for example 54 thou, our brain can quickly work out a guesstimate with ease and accuracy. To measure this gap, you can use a string height digital indicator such as those sold by LMII.

If you were to pick up a television remote control and guess the thickness of that remote control to within 2 thou, that IMO is impressive. Not saying it cannot be done, but way- way beyond my capability.

Steve

[Hot Vibrato]

Originally Posted by mirwa

A difference exists in comparative assessment and general guesstimate.

If you have a thin string, you know approximately what it is before touching, one can guesstimate quite easily which gauge of string has been used.

Guesstimate a gap between a fret and string is another example of comparative assessment, we know frets range in the 30-50 thou crown height, we know the string going over the top is for example 54 thou, our brain can quickly work out a guesstimate with ease and accuracy. To measure this gap, you can use a string height digital indicator such as those sold by LMII.

If you were to pick up a television remote control and guess the thickness of that remote control to within 2 thou, that IMO is impressive. Not saying it cannot be done, but way- way beyond my capability.

Steve

I couldn't guess the thickness of my TV remote control that accurately, but that's different. It's easier with smaller things, and as you said, if you know the size of one thing, you can use that as a proportional reference to judge the size of something else. For instance, a .002" gap is about 20% the size of a high E string. That makes it much easier to judge that gap if you keep that in mind.

[LouieAtienza]

Originally Posted by Bruce Sexauer

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.

I was a huge Beatles fan, so I would listen in my mind the opening open A string on "I Feel Fine" as it feed back and buzzed against the fret, and that's how I tune to A.

[karlitofingers]

Originally Posted by Hot Vibrato

I was practically laughed off the gearslutz forum for saying I can estimate small distances accurately to within a couple thou. They jumped all over me for saying that when adjusting a nut slot, for optimum playability, the margin of error is about .002". I told them that I measure to the thousandth of an inch every day, and think in those terms every day, and I can eyeball a .002" gap between the top of the fret and the bottom of the string. I was scoffed at and ridiculed something fierce. It was absolutely infuriating.

I was told that I have no way of knowing a measurement without actually measuring it, and therefore have no right to declare that something is .002" without confirming it with a measuring device. But how do you even measure a .002" gap? They don't make feeler gauges that thin. I don't need a measuring device to know I'm right.

I eyeball other things using thousandth. If I'm setting up a flattop, when measuring the string height at the 12th fret with a ruler (with 1/32" increments), I judge the amount I want the action to come down (or up) in thousandths of an inch, and remove double that amount from the bottom of the saddle. It works well for me. I estimate conservatively, so sometimes it takes two passes.

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?

If it helps, I always do final filing etc using feel and eye only. For example went I fine tune the nut slots during a set up I don't just lay a feeler gauge on the board and file down to it, it's all done by filing and putting the string back up to pitch and checking. Yes I measure everything before hand, but ultimately my eye and feel is the factor that ensures the setup is perfect. I think this only comes with experience of doing the same jobs over and over.


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[Sperry]

There was a postal employee I knew who could tell you if an envelope contained one or two bills of US currency.

Which measure, incidentally, a thou each

[murrmac123]

Originally Posted by Sperry

There was a postal employee I knew who could tell you if an envelope contained one or two bills of US currency.

Which measure, incidentally, a thou each

A US treasury bill is only .001" thick? .... I very much doubt that ... although it's many years since I had one which I could measure.

[Sperry]

Originally Posted by murrmac123

A US treasury bill is only .001" thick? .... I very much doubt that ... although it's many years since I had one which I could measure.

Well, I humbly confess to be wrong ... all those years ...

A bill is 124 microns ± 7 micron. Which is, naturally, 0.004"

Someone told me decades ago that a bill weighed a gram and a thousand would be a 1" stack ... Not the first time I learned something wrong. Used to think meat grew on trees, after seeing an image of long strips of giraffe meat drying on tree branches in Africa.

[Pat Foster]

I for one believe you, Hot Vibrato. I had about the same abilities as mirwa when I worked in machine design and was able to prove to my coworkers that I could. I still relish that moment.

I think if you work long enough to fine tolerances in dimensions, color or sound, you can get really accurate. When I was doing guitar repairs, I got to where I had perfect pitch, but now, just building, I don't tune a guitar to pitch often enough to stay "in shape."

[Hot Vibrato]

Originally Posted by murrmac123

A US treasury bill is only .001" thick? .... I very much doubt that ... although it's many years since I had one which I could measure.

Times are that hard, eh?

Oh wait - you're in Scotland. Never mind...

[murrmac123]

Originally Posted by Hot Vibrato

Times are that hard, eh?

Oh wait - you're in Scotland. Never mind...

I just measured a Scottish £5 note (we call them notes here rather than bills) and I make the thickness to be .003"

Nowadays these notes are printed on polymer, as they also are in Australia and Canada .... I suspect the previous paper notes were a tad thicker, probably the same .004" as the dollar bill.