Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Edge finder/ Center finder question

On an edge finder there are two ends. The end you use to find the edge is
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.

Does any one here know?

--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.


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Default Edge finder/ Center finder question

On Jun 7, 2:42*pm, "Roger Shoaf" wrote:
On an edge finder there are two ends. *The end you use to find the edge is
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.

Does any one here know?

--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.


Clamp it in the chuck and run the point down into the hole, lightly. I
think you're supposed to mike across the sliding joint and adjust
until it reads whatever the shank diameter is, but I just slide my
fingernail over the step and move the table until I can't feel it on
any side.

Once you've located the edges you can put the pointed end down to
confirm that your 0,0 position really is the corner of the work, you
didn't locate on a chip.

A burr or countersink can easily throw off the center finder. I just
had to adjust some holes positions by 0.015" because the burr on a
hole apparently shifted the countersink and I misplaced the vise stop
on the next setup.

Jim Wilkins
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Default Edge finder/ Center finder question


....
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.

Does any one here know?


I was hoping somebody would give a better answer than mine. Seems you're not
getting an answer.

I've not seen anybody else do this, so there may be a better way. On a very
small hole, the pointed end will tell you which side you hit first as you
lower the quill. Make an adjustment and try again. When you're all the way
down, you're right over the center of the hole.

Karl


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Default Edge finder/ Center finder question

"Roger Shoaf" wrote:

On an edge finder there are two ends. The end you use to find the edge is
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.


I use the finger nail method. Tapped holes are going to be a problem though.

Turning a tight pin to stick in tapped hole and indicating that might be more accurate.
Usually when you are tring to pick up such a hole, there is something broken in it though


Wes
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Default Edge finder/ Center finder question

On Jun 8, 4:08*am, Wes wrote:
"Roger Shoaf" wrote:

I use the finger nail method. *Tapped holes are going to be a problem though.

Turning a tight pin to stick in tapped hole and indicating that might be more accurate.
Usually when you are tring to pick up such a hole, there is something broken in it though


Wes


Usually when I've had to measure a tapped hole pattern it was to drill
a mounting plate to match. I just put setscrews or Phillips heads in
and visually pick up the center, or for better accuracy chuck a
matching screw in a collet and turn a point or center hole on it. Two
little flats ground on the sides make it removeable with tweezers.

When I asked the machine shop to measure one particularly critical
pattern they used a height gage to measure snug-fitting pin gages in
the holes, but I still had to open up the resulting mounting holes a
little to make the screws fit. I think the tap may have raised an
uneven burr on the ID of the threads.

If I really really had to be accurate I'd single-point a thread that
fits snugly and make my own center plug. A small 5C-mount chuck works
well for a part that has to be removed to check the fit.

Jim Wilkins


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Default Edge finder/ Center finder question

On Sat, 7 Jun 2008 21:24:19 -0500, "Karl Townsend"
wrote:


...
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.

Does any one here know?


I was hoping somebody would give a better answer than mine. Seems you're not
getting an answer.

I've not seen anybody else do this, so there may be a better way. On a very
small hole, the pointed end will tell you which side you hit first as you
lower the quill. Make an adjustment and try again. When you're all the way
down, you're right over the center of the hole.

Karl


The point of an ordinary scriber fitted in the chuck can be
used to locate an edge, a scribed line or a centre punch dot.
It's pretty rough and ready because the point can be a bit cock
eyed and not accurately represent the true spindle axis.

The pointy bit of the edge finder set is intended to do the
same job but eliminate the spindle axis error.

Set the pointer end roughly on axis and close to a flat
surface. Run at any convenient low speed and with a finger
resting on the surface SLOWLY edge the point in until the point
reaches dead centre and no longer rotates around a small circle.
The point is now dead on the axis of the spindle.

It's pretty easy to learn to do this and it only takes
seconds. It's then a versatile location finder.

This is the way it is supposed to work but the downside is
that it means removing the cutter and replacing it with the edge
finder. A more convenient kludge is the "sticky pin" system.

In ancient UK terminology a gramophone needle is stuck to
the end of the already installed cutter with a lump of
Plasticene. The point of the needle is then centred by finger
pressure. It needs a little more skill to do this because, until
you're used to it, both ends of the needle may initially be way
off centre. However it's a skill well worth aquiring as it's very
much quicker than messing about changing between cutter and edge
finder.

Not sure about the North American equivalant. Gramophone
needles are pretty rare now but the cut off end of a thick sewing
needle does the same job.

Plasticene is a propriety brand of modelling clay which
happens to have sufficient "stickyness" without being "rubbery".
This zero "rubbery" is vital as the point mustn't spring back
once it's centred.

Jim



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Default Edge finder/ Center finder question

On Jun 7, 2:42*pm, "Roger Shoaf" wrote:
On an edge finder there are two ends. *The end you use to find the edge is
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.

Does any one here know?

--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.


Adjust the X and Y axis so that the pointed end of the center/edge
finder is approximately in the center of the hole somewhat below the
surface. With the spindle running slowly, move the X axis until you
see the kick. Note the reading on the dial. Now move the X axis slowly
in the opposite direction until you see the kick. Note the dial
reading. Subtract the smaller reading from the larger. Now move the X
axis toward the center of the hole for half of the calculated
distance. The center finder is now exactly at the center of the hole's
X axis. Repeat for the Y axis and you have found the exact center.
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Default Edge finder/ Center finder question


"rgoldner" wrote in message
...

Adjust the X and Y axis so that the pointed end of the center/edge
finder is approximately in the center of the hole somewhat below the
surface. With the spindle running slowly, move the X axis until you
see the kick. Note the reading on the dial. Now move the X axis slowly
in the opposite direction until you see the kick. Note the dial
reading. Subtract the smaller reading from the larger. Now move the X
axis toward the center of the hole for half of the calculated
distance. The center finder is now exactly at the center of the hole's
X axis. Repeat for the Y axis and you have found the exact center.


Sounds good except for the backlash. I suppose if you had a DRO this would
work just fine.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.


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Default Edge finder/ Center finder question

"Roger Shoaf" wrote:

Sounds good except for the backlash. I suppose if you had a DRO this would
work just fine.


long travel dial indicator and magnetic base?
http://wess.freeshell.org/usenet/rec...se_closeup.jpg

Sit it on way and measure away...

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Default Edge finder/ Center finder question

On Jun 8, 9:46*am, rgoldner wrote:
On Jun 7, 2:42*pm, "Roger Shoaf" wrote:

On an edge finder there are two ends. *The end you use to find the edge is
pretty straight forward, but the pointy end is supposed to be for finding
the center of holes, but for the life of me I cant seem to figure out how
this is supposed to work.


Does any one here know?


--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.

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