# How to use a Conical Edge Finder



## vascon2196 (Apr 24, 2012)

Hi Folks...

I have a double ended edge finder. One end is 0.200" diameter and the other is conical.

My question is how to properly use the Conical end?

As of now I stuff the Conical end into an existing hole (while the machine is OFF), then jog the table around until it appears to be true by eye. Should I have the mill on when doing this?

The 0.200" diameter "kicks-out" but does the center (conical) end do this as well?

Thanks for the input...YouTube had nothing to offer. (none that I could find)

Chris


----------



## IronHorse (Apr 24, 2012)

I use my fingers to "feel" if the tool is aligned. I have had good success with this tool for finding punch marks on material. I can actually make a 4 bolt cover and it will line up to the holes in the cylinder perfectly!!!

I bought it on sale a few years ago, and I did not know what it was for, I thought it would make a good edge finder. Then I saw someone on the web demonstrating it and have being using it ever since


----------



## Jasonb (Apr 24, 2012)

26mins into this video shows you how to use one

http://techtv.mit.edu/videos/142-machine-shop-1

J


----------



## mklotz (Apr 24, 2012)

I use my fingers too to determine when it's aligned. (Human fingertips are incredibly sensitive.) If you want to be OCD about it, use a mike to measure the diameter across the split. When it matches the diameter of the edge finder barrel all the way around you're there.

For holes too large for the cone on the edge finder, I made several gadgets of my own design. Picture a short cylinder with a large male cone on one end and a small female conical hole on the other end. The large cone end sits in the subject hole and the conical point on the edge finder goes in the small conical hole. A close-fitting ring encircles the cylinder and forces it to remain more-or-less vertical.

It's only meant for less than critical hole alignments. When something needs to be dead nuts on I'll break out the DTI and do it according to the books. 

If my description of the gadget is too obscure, give a shout and I'll take some photos.


----------



## vascon2196 (Apr 24, 2012)

Jasonb  said:
			
		

> 26mins into this video shows you how to use one
> 
> http://techtv.mit.edu/videos/142-machine-shop-1
> 
> J



WOW 
What a great video! I am going ti use this site next semester with my students!
And now I have a much better understanding of how to use my center finder.

Thank you,

Chris


----------



## vascon2196 (Apr 24, 2012)

Thank you everyone...very helpful.

Chris


----------



## kwoodhands (Apr 24, 2012)

vascon2196  said:
			
		

> Hi Folks...
> 
> I have a double ended edge finder. One end is 0.200" diameter and the other is conical.
> 
> ...



The mill is turned off ,the table is moved in the X&Y directions until the edge finder looks right and feels smooth all around. Then raise the tool off the work and turn the mill on.If the tool spins without wobbling the center is established.
I use another method when finding centers that have been laid out but not punched.Take an old or broken tap, place in an electric drill. Run the tap at a shallow angle to a grinding wheel. This will give you a long concentric point.I chuck this in the mill, center the work by eye with the point.I believe that I can center a layout line within .001 using this simple method. 
Try it,costs nothing.
mike


----------



## mp7042867 (Jan 24, 2020)

Interesting but the centre will not precise as it will never be better than the accuracy of the punch mark and it relies on the spindle running true. 
Better to find two edges and zero the readout. Pitch across the right distances and you have you hold location. 

Alternatively use a toolmakers button and slip gauges or micrometers and centre the spindle with a lever type dial indicator.

Or you can just centre punch a mark 20 thou deep and start a hole in your part with a small drill that can bend a small amount to follow the punch mark after you move the part as lose as you can under the spindle. This assumes a small part that can move easily on the table.  A larger drill will pull the part in line with spindle as you drill out to the final size.


----------



## ninefinger (Jan 24, 2020)

mp7042867 said:


> A larger drill will pull the part in line with spindle as you drill out to the final size.


This assumes that you have not clamped the part and / or vise to the machine table - which can be a very dangerous way to operate, especially with larger drills.  I strongly disagree with this and would not recommend it to anybody.


----------



## dsage (Jan 25, 2020)

Ever heard of the Osbourne maneuver?
Eyeball center to get close first.
Put the cone slightly in the hole with the mill running and use the kick to perform the maneuver.
The end is conical so it will fit in (almost) any sized hole.
For large holes (like 1" or more) you can use the straight sided end the same way.


----------



## johnl (Jan 25, 2020)

The conical end can also be used to find the center of round stock, such as locating the center of a shaft to cut a keyway.


----------



## blockmanjohn (Jan 25, 2020)

This is probably obvious, but never let the conical point touch the part while it is centered in a hole and the spindle is turning. The point will spin and ruin the spring inside of the tool. First hand experience. John


----------



## justintime (Jan 25, 2020)

blockmanjohn said:


> This is probably obvious, but never let the conical point touch the part while it is centered in a hole and the spindle is turning. The point will spin and ruin the spring inside of the tool. First hand experience. John


Proper use of the tool requires spindle to be rotating.  Total concept of the tool depends upon that spinning action.


----------



## blockmanjohn (Jan 25, 2020)

I 'm sure my post wasn't very clear, and you are absolutely correct. What I was trying to say was if the conical side goes into the hole on center while the spindle is turning, and any down pressure is supplied, it will cause the conical part to stop spinning and ruin the spring. John


----------



## ALEX1952 (Jan 25, 2020)

Before the advent of wobblers etc we were taught to pu a knob of putty or similar on the ebd of the chuck and stick a pin in it vertically, run the machine and move the pin with a pencil/finger  whatever so that it runs true, and with young eyes you can center a job very accurately (I was 16 at the time now 68 oh dear,). When wobblers/center finders came along we were in awe and wanted one but they were very expensive this would be the late sixties.


----------



## colby15642 (Jan 25, 2020)

Another problem with the pointed-end center locator is that the surface in which the hole to be measured is drilled has to be smooth and precisely perpendicular to center-line of the finder.  Otherwise, the finder's cone surface will always contact the highest side of the hole and produce a undesirable and consistent offset in the centering process.


----------

