Ability of Fingers to feel tolerances

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beck3906

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I had read/heard there was some study done on the finger's ability to feel tolerances. I've done some Google searching but cannot find anything. Does anyone know of a reference?

I'm looking for the ability to feel the tolerance between the transition of a nib and the body, for example.

Thanks for any help.
 
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touch does vary and yes you can feel very minute differences. The biggest hurdle is really being able to feel, most people ignore most of that sensation.
 
A magician I knew said he would practice with a deck of cards until he could tell by feel how many cards he pulled off when he cut the deck.

To apply to your nib/body transition, try a few measured differences and see what you can detect.
 
I don't know the numbers, but when I was working in medical r&d, in the shop we often worked to .001". I can tell you from personal experience that I can feel differences a lot smaller than I can see (and that was before I needed glasses).
 
Its probably in the neighborhood of .001 to .002, but the challenge is to find nibs and a turning that have 0 runout. If not, there could be 0 tolerence on one side and more on the other.
 
BRobbins629 said:
Its probably in the neighborhood of .001 to .002, but the challenge is to find nibs and a turning that have 0 runout. If not, there could be 0 tolerence on one side and more on the other.
Click to expand...

I agree, I don't have as fine of touch feeling as I used to, but I can still feel a .002 difference in size, on a good day MAYBE .0015. and I work on machining 4 to 6 hrs a day.
 
If you're turning wood pen barrels, they will expand and contract with changes in temperature and humidity (and age), so even if your barrel mates with component parts perfectly when you ship, they'll eventually be different enough to feel.

The same is true when segmenting with different woods.

The trick is to minimize the transitions so that one doesn't notice the difference. Sharp edges are more discernable. A very small radius on the edge will go a long way towards making things feel smooth. A quick twist against a piece of sandpaper held at an angle will knock the edge off.

If you use different woods with different coefficients of expansion, lining up the grain when cutting segments generally helps.

Regards,
Eric
 
You can feel much more if you place a thin cotton cloth between your fingers and the surface you are feeling. I learned that in the bodyshop finishing used cars.
Charles
 
I actually close my eyes and run my fingers along what ever I'm working on,
the sense of sight sometimes tricks your mind into not seeing a variance or to
give you the OK sign by not seeing the area in question as a flaw, your full senses are in your finger tips when your eyes are closed,
 
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