Author Topic: Finger calipers  (Read 449 times)

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Offline DC

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Finger calipers
« on: September 13, 2017, 12:26:33 pm »
Just wondered if anyone had ever measured the accuracy of their "finger calipers"? I'm running my fingers up and down a bow limb that I know has a .020" variation and I can't feel it.
Vancouver Island

Offline stuckinthemud

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Re: Finger calipers
« Reply #1 on: September 13, 2017, 01:03:32 pm »
My fingers are great at finding imperfections that my eyes can't see but I cannot get the same accuracy from them as a ruler, marked-off piece of paper, or calipers; even though some of the senior members of PA can, its not a skill I have been able to develop.

Offline Pat B

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Re: Finger calipers
« Reply #2 on: September 13, 2017, 02:21:38 pm »
I can feel a thickness change with my fingers. I don't know how accurate it is but I've never had a problem with it for the 30 years I've been doing it. I just can't make myself use calipers on a selfbow.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline BowEd

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Re: Finger calipers
« Reply #3 on: September 13, 2017, 02:45:37 pm »
My finger tips will feel variations very good.Their used all the time.While tillering that's all I ever use.Variations prevent any chrysalling or stress before any big bending past 20".Looking down the belly at a low angle towards the light helps me too.Ask any machinest how sensitive those finger tips are.A person can go either way in the beginning either making a fat tapered 3/8" line on the side and go or measure it out with a ruler or calipers in the beginning phase.Does'nt matter to me.The finger tips wlll not tell me the exact thickness number wise though but close.Ether way either in a primitive situation or in the shop.A numbness in the finger tips to not feel properly usually means not the proper blood flow I imagine.I have 1 middle finger tip that's numb though from a speed grinder accident and scar tissue is the reason I imagine.
Beadman
You got to stand for something or you'll fall for anything.
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Offline George Tsoukalas

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Re: Finger calipers
« Reply #4 on: September 13, 2017, 02:59:53 pm »
Yes, indeed. The bowyer that uses only sight is 1/5 the bowyer he could be. :) Jawge
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If you ain't breakin' you ain't makin!

Offline DC

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Re: Finger calipers
« Reply #5 on: September 13, 2017, 03:02:58 pm »
As long as it's an even smooth taper I do not too badly. If I hit a knot or a lump that spreads my fingers a bit when I get back on the straight sections I've lost it. I've done enough machining to know how little it takes to notice but a machinist will be running their hand along a section that is exactly .500" and then jump to .505" and feel it but that's not quite the same thing.

Also while we're at this, the back of a stave is rarely even. It can go from flat to crowned to concave. How do your fingers and brain deal with that? Does that get into that other elusive talent, judgement call. ;D
Vancouver Island

Offline PEARL DRUMS/PEARLY/PD/DRUMS

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Re: Finger calipers
« Reply #6 on: September 13, 2017, 04:50:00 pm »
Close your eye to get the full effect.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Online PatM

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Re: Finger calipers
« Reply #7 on: September 13, 2017, 05:34:09 pm »
Tiller by the visual bend, not the thickness. ;)   

Offline Hawkdancer

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Re: Finger calipers
« Reply #8 on: September 13, 2017, 07:26:01 pm »
Most of us can see about 1/100th of an inch, "just a hair width", and can feel on average about half a 1000th. A person with a good feel can detect a 1000th or less.  A real good machinist or tool and die maker even finer!  Me, yeah, feels a bit smooth here or rough there! Let's have a drink >:D!  I work by feel a lot, because I don't know where the calipers are!
Hawkdancer

Offline mikekeswick

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Re: Finger calipers
« Reply #9 on: September 13, 2017, 10:24:26 pm »
A tool is only as good as the person using it ;)

Offline Stick Bender

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Re: Finger calipers
« Reply #10 on: September 14, 2017, 01:09:21 am »
I like to use digital calipers to work in a ruff taper prior to floor tiller and then fingers and a combo of caliper fingers ,takes care of for the most part weight robbing set causing hinges out of the gate sense I have been using that method my bows are turning out much better and quicker to tiller with less set , I cant tell you by fingers if its 1/1000 difference but can defently fell diferences in the taper !
If you fear failure you will never Try !

Offline Dances with squirrels

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Re: Finger calipers
« Reply #11 on: September 14, 2017, 01:53:33 am »
I'm half decent with my thumb and finger but made the thickness gauge on the left because it's a lot more accurate and I can run it down the limb and in 3 seconds know what's going on with the thickness taper. It can also be used to quickly check the thickness from side to side. I generally don't even use it to 'measure' the thickness per se, just slide it down the limb from dips to tips and watch the dial to see if it continually and steadily rotates counterclockwise. The bottom part that rides against the back of the bow is rounded and it slides a lot easier than dial calipers.
« Last Edit: September 14, 2017, 01:56:55 am by Dances with squirrels »

Offline Aaron H

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Re: Finger calipers
« Reply #12 on: September 14, 2017, 04:06:16 am »
I made one very similar to DWS a couple years ago, but rarely do I ever get it out of the toolbox
But those who put their trust in the Lord will find new strength. They will soar high on wings like eagles...     Isaiah 40:31