On Sat, 16 Aug 2008 08:53:06 -0700 (PDT),
wrote:

On Aug 16, 3:12 am, Winston wrote:
F. George McDuffee wrote:

(...)

=========
Anyone have accuracy numbers for the cheapscrew method of using a
dowel pin and feeler gage or slip of paper?

I dunno, but as a data point, teenut appears to say one can locate to
within a tenth using oiled tissue paper and a mounted cutter.

http://yarchive.net/metal/edge_finders.html

See entry "Wed, 05 Jan 2000 23:07:11 GMT"

--Winston


George, (I'll be 63 this fall)

I read teenut's article you referred to; in fact I read the whole
list.

When you asked about the accuracy of the dowel pin-in-collet plus
cigarette paper method of edge finding, and if you wanted to locate
the spindle centre line over the edge, then my posting above is
correct in that the collet/spindle/pin run out limits the accuracy of
edge location.

However, after reading teenut's old post it occurred to me that you
may be talking about locating a work piece edge with the edge of a
milling cutter. This is a horse of a different colour because here we
want to determine the EFFECTIVE diameter of the cutter because the
location of any edge machined, from the located edge, is determined by
that EFFECTIVE cutter diameter which includes its wobble and run-out.
The paper-stuck-on-work edge is very effective for this purpose.

I have seen people use feeler gauge stock to do this but I wouldn't do
that to a sharp cutter. Brass shim stock is what I have used for this
purpose because its thickness is easily added to any dimension. With
cigarette paper it is hard to tell how much to allow for; I suppose
for most purposes the .001" thickness of the paper is ignored.

Wolfgang
=============
Use your micrometer to verify the paper thickness -- seems to be
very consistent within a packet.

You appear to be correct in that the centerfinder used in the
kick-out mode will compensate for some collet eccetricity, and
does allow for checking under power/rotation, while a dowel pin
and feeler gage will not.

FWIW - I use an electronic edge finder like this one.
http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32
Anyone have date on these?

Wish I had a Schmidt if only to put in my tool box and look at.
https://www.hermannschmidt.com/produ...&idproduct=148

Also what has the groups experence been with the "audible" edge
finder with a flat ground on the tip to produce a clicking noice?
Less accurate? More accurate? than the standard edge finder?
for examples see
http://www.cartertools.com/fm.html#hfef
(about 2/3s of way down)
http://brownandsharpe.com/precision-...le-edge-finder


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).