Subject: Help: How do you use a centerfinder/ edge finder.

From: cw thomas <[email-masked]>
Date: Thu, 06 Jun 1996 16:10:24 -0700

Hi;

 Thanks for reading this. I bought a center finder  and a wiggler set 
 and found that it didn't come with instrucions. Can sombody please 
explain to me how they work?

 The centerfinder (dual use point on one end flat on the other.) is a 
steel cylinder with a point on one end and a small drum on the other
 connected thru the center with a spring.  The thing is polished so that
 the ends fit smoothly.  

 Also I bought a wiggler set Which is composed of a holder ( kind of like
 a drill chuck but designed with a socket to accept the ball on the end 
of the wiggler? ( it came with one holder and 4 different things that
 have balls to fit into the socket thing which I assume fits into the 
 mill or drill press chuck.

 Thanks;

 C. W. Thomas

---

From: PPIERCE <[email-masked]>
Date: Thu, 06 Jun 1996 17:22:38 -0700

cw thomas wrote:
> explain to me how they work?.......
>  ..Also I bought a wiggler set Which is composed of a holder ( kind of like

I know the feeling....  Then I took a semester at a community college (night) which 
really helped.  But the best was just a couple of weeks ago when I spent the afternoon 
playing with both the wiggler and the centerfinder.  I'm still not sure of the conical 
end of the c/f.

In class the instructor was telling us how the c/f would jump about 1/32" when it was 
at the edge (less the radius of the c/f.  Problem I was looking the wrong direction- 
you must look perpendicular to the work edge...  Finally it dawned on me...

The wiggler uses either the ball end or the small disk to find the edge.  Get it 
running nearly true and approach the work.  I didn't have to guess.

The little point attachment must be running true.  DON'T use a thumbnail!!!  I usually 
use a 6" rule.  Look down your layout marks and/or centerpunch mark.  Not too hard to 
get located.

Playing with those gadgets made for a real satisfying experience.  Found that I could 
get pretty close repeatability

Also cigarette papers...  They are .001 thick.  Held against the work while approaching 
with a milling cutter, you will get the indication of the edge as the paper is snatched 
out of your finger.  One of the Village Press authors suggests a wax crayon mark on the 
work, approach the mark carefully, when the cutter touches the wax you're there.

Have fun - I am...

Paul in AJ AZ

---

From: [email-masked] (robert a barker)
Date: 7 Jun 1996 03:04:37 GMT

In article <[email-masked]>, [email-masked] says...
> mill or drill press chuck.

 The edge finder is put into the spindle collett or chuck with the small
dia shaft hanging down.Usually the small dia is .200 " in dia.When the 
spindle is running,the smaller dia can be pushed or tapped and it will
run eccentrically.If you then dial the machine so the workpiece touches 
the smaller dia,it will cause it to run true.Dialing *very slowly* and 
watching closely,you will suddenly see the end jump to one side.at that 
instant,the center of your spindle is exactly one half of the dia (.100")
away from the work.

  The wiggler works on th same principle.

  Hope this helps.

  Bob Barker

---

From: Mike Rehmus <[email-masked]>
Date: 10 Jun 1996 17:02:25 GMT

I have to disagree on the statement that the Wiggler works 
the same as an Edge Finder.

The Edge Finder is a dynamic indicator of the location of
an edge, the Wiggler is a pointer on the centerline of the 
longitudinal axis of the spindle to which is attached.

It is a correct statement that the Edge Finder will 'kick'
sideways when it contacts the edge of the work.

A few more tips:

1. Do not chuck the Edge Finder with excessive pressure.  It
   is hollow and can be crushed.

2. You should run the Edge Finder at about 1000 rpm.

3. The spindle should be down so that when you see the 'kick',
   you can retract the spindle and remove the Edge Finder
   from the workpiece.  This saves wear and tear on the
   lapped surfaces of the Edge Finder.

4. View the workpiece/Edge Finder contact by aligning your eye
   behind the Edge Finder and at 90 degrees to the workpiece for
   maximum visibility of the 'kick'.

5. Oil the Edge Finder maybe once a year if you only use it occasionally.
   You may have to pull the pieces just slightly apart to get the oil
   in between them.  Be careful.  If you distort the spring holding the
   pieces together, you will need a new Edge Finder.

6. Make certain there are no burrs on the workpiece or you will get a 
   false edge indication.  The same goes for excessive oil on the
   workpiece.
7. Cheap Edge Finders are probably not worth the effort to take them
   home.  A Starrett does not cost a lot of money and the difference in
   accuracy and ‘action’ between a cheap unit and a Starrett is noticeable.

Wigglers.

Wigglers are used to indicate the axis of the spindle to which they are 
temporarily attached.  In practice, with the spindle turning at about 
1000 rpm, the probe is centered (described later) and then the user 
visually centers the workpiece under the spindle (or the reverse).  
By carefully observing the relationship of the probe and the workpiece, 
the user can center the workpiece within one or two thousandths of an inch.
Wigglers usually come in a small kit with a body and four or five probes, 
each of which have a ball on one end that fits into a socket on the body.  
The socket has a means of tightening the socket/ball fit so that the tool 
will work properly.  One of the probes is bent, with relatively large 
balls on each end.  This probe is to hold a dial indicator.

To use, pick a probe with an end appropriate to the indication required.  
If you want to pick up a scribed center mark on the workpiece, you would 
use the pointed probe.  If you needed to locate the center of a hole, you 
would use a probe with a larger end.

Once you have the probe snapped into the body, tighten the socket until 
a fair amount of friction is felt.  Do not lock the probe in the body.
Next mount the body in the spindle and center the probe with your fingers.
  
Then start the spindle at about 1000 rpm with your hands away from the 
business end of the Wiggler.  You will  probably observe that the probe 
is now spun out to near horizontal (the socket is too loose) or it is 
spinning in a near-perfect and small circle along the spindle axis.
  
Using an object like a pencil (ideal), press the object on the side 
of the probe down near the business end.  Press in towards the spindle 
axis and you will observe several phenomena.

1.  The probe will move to absolute center.
2.  It is hard to move the probe off center with the pencil.
or
3.  If the socket was too loose, the probe is now trying to become 
    a helicopter blade.  If so, stop the spindle and tighten the
    socket some more, reset the probe in the vertical position and 
    start the spindle again.

Now that the probe is running in alignment with the spindle, you can 
use it to align the workpiece or spindle to the proper location.

In practice, when aligning a center point, I find it useful to observe 
the sharp probe/workpiece relationship with a magnifying glass and from 
at least two locations 90 degrees apart.  Sometimes I try to look at 
the relationship every 45 degrees or so.  Done carefully, you can 
achieve an alignment within one or two thousandths of an inch.

When using the Wiggler to find the center of an existing hole, 
I use a probe with a size near that of the hole.  Then, after going 
through the probe alignment procedure, I lower the ball-end of the 
probe into the hole by half of  its diameter.  Then it is a simple 
matter to look at the space between the probe ball and the wall 
of the hole and adjust the workpiece or the spindle position until 
the space is even all around.

When using the bent probe to hold an indicator, the socket has to 
be locked rigid.

Hope this helps.

Mike Rehmus

---

From: Michael Jones <[email-masked]>
Date: Tue, 11 Jun 1996 12:41:47 GMT

>explain to me how they work?

You can see a video of how to use a centerfinder at the MIT machine tools 
site. It's always helpful to *see* someone actually use one.

Sorry I don't know how to make it a proper clickable url.

http://me.mit.edu/2.70/machine/mill/intro.html

Mike Jones

---

From: PPIERCE <[email-masked]>
Date: Tue, 11 Jun 1996 09:32:45 -0700

> http://me.mit.edu/2.70/machine/mill/intro.html

Mike it came out clickable...  Looked like it could be a real
fantastic net page.  I couldn't view the video.  Netscape says
I need a plugin viewing software.  I'll try one of these days.

Thanks for the address...

Paul in AJ AZ

---

From: PPIERCE <[email-masked]>
Date: Wed, 12 Jun 1996 09:06:40 -0700

> http://me.mit.edu/2.70/machine/mill/intro.html

Mike:

I made a previous reply but note that it only went to the newsgroup
and not to you personally...

You sure did make that web page clickable.  I guess that the newsgroup 
recognizes web pages.  That looks like a fantastic page but I'dd like
to know what to use as a viewer.  Netscape does not read videos and
says I need a viewer but although they offer several I know not what
is required.

Does MIT also have a lathe page, etc..?

Thanks again for your input.

Paul in AJ AZ

---

From: [email-masked] (John Dammeyer)
Date: Thu, 13 Jun 1996 07:27:03 GMT

>> cw thomas <[email-masked]> wrote:
[snip]

>Paul in AJ AZ

Super video.  I always wondered how they work.  Now I've seen it.

BTW.  Just above the /mill/ directory they have the rest of the
machine shop videos.  Some are a bit short but overall the quality is
excellent.

John.

---

From: PPIERCE <[email-masked]>
Date: Thu, 13 Jun 1996 10:32:13 -0700

> machine shop videos.  Some are a bit short but overall the quality is

John::  Mike: Someone:

What viewer should I get to view the videos on this...
Netscape does not work without a plug-in.  But what plugh-in?

Paul in AJ AZ

---

From: PPIERCE <[email-masked]>
Date: Sat, 15 Jun 1996 07:06:17 -0700

Michael Jones wrote:
> snip...
> Actually, this is a question I'd like to know the answer to. The
> university here provides us with only the the barest minimum of network
> tools, including Netscape.  But their movie viewer doesn't work on my
> university provided Pentium, so I download movie files and view them on
> my Mac. With my Mac I use either Sparkle or view them with Movie Player.
> 
> I'd love to see the all the metal working videos at the MIT site, but
> some are too big to fit on a 1.4Mb floppy...sigh.
> 
> Mike

Frustrating isn't it???

Paul in AJ AZ

---

From: [email-masked] (John Dammeyer)
Date: Sat, 15 Jun 1996 14:46:59 GMT

>Paul in AJ AZ

Depends on the computer and OS you are using.
If a MAC - who know???

If a PC running WINDOWS 3.11 or Windows 95 VMPEGWIN.EXE works nicely.

If you are using WIN-NT 3.51 then there is the likelyhood of a General
Protection Fault. Why? Well the program is doing something that it's
not supposed to and WIN-NT is the only OS that catches it.  This is
why WIN3.1 needs to be periodically rebooted - software like this
makes it unstable.

I don't recall where I found it but a search of the web using Yahoo
should turn it up.
John.

PS. So I still use NT for everything except mpg videos and then I just
run them on my kids Packard Bell running WIN-95.  With all the various
games they run their machine is rebooted daily anyway. My NT systems
goes for months without being turned off or rebooted.