Finger calipers

[DC]

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.

[stuckinthemud]

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.

[Pat B]

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.

[BowEd]

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.

[George Tsoukalas]

Yes, indeed. The bowyer that uses only sight is 1/5 the bowyer he could be. Jawge

[DC]

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.

[PEARL DRUMS]

Close your eye to get the full effect.

[PatM]

Tiller by the visual bend, not the thickness.    

[Hawkdancer]

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 !  I work by feel a lot, because I don't know where the calipers are!
Hawkdancer

[mikekeswick]

A tool is only as good as the person using it

[Stick Bender]

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 !

[Dances with squirrels]

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.

[Aaron H]

I made one very similar to DWS a couple years ago, but rarely do I ever get it out of the toolbox