Re: RE: Lighted edge finder

Jon Elson wrote:
<snip>The edge finders are much better (and safer, too) for locating

>edges,but they don't do as well on punch marks.

Had one of my machinists show me how to use the "pointy end" of an
edge finder. This would be the combo kind w/ a .2 cylinder at one end
and a cone on the other.

To use, prick or punch the hole location. Do this carefully and
accurately(punch held vertical), the center finder will EXACTLY find
the bottom/sides of this punch mark.

Now jog the axes 'til edge/center finder is neatly above the punched
mark. With the spindle about 5-800 rpm, use a fingernail(hey, that's
what the old guy used!)or something else to "true" the cylinder/cone
joint.

Then bring the point down into the punch mark and the center finder
will DEFLECT the amount you are off the punched location. So you can
adjust the axes until the cylinder runs true again; or you can stop
the spindle with the quill down and "mike" the major cylinder dia.
across the joint(cylinder typically is .375 or .500) If the
measurements are taken in line with the axes they will show the EXACT
distance the spindle is "off" from the punch mark.

This works really well! I use the scribe from an old Starrett combo
square to make the original mark. It can be a really small mark and
still work, you just have to be careful (if it's small) to be WITHIN
the punch or you may make a NEW punch "mark" WITH the center finder!

Hope this helps.

Ballendo