Using a center finder?

dhepler · Jun 20, 2011

I have used an edge finder a lot but have never understood how to use and the applications for the pointed end of an edge finder (not a common wiggler)

Mulva · Jun 20, 2011

I've used it to center on an existing hole or punch mark.

Cole2534 · Jun 20, 2011

So how does it work?

Winterfalke · Jun 20, 2011

If you are referring to the 45 degree end, I have seen it used once to locate off a chamfered edge of a part, it touched off the parts top surface, then lowered until it could contact the chamfer and was used normally. Then maths ensued. The amount it was lowered from the surface was equal to the offset from the center of the edge finder I believe? Not sure if this is the proper way to use it, don't have one myself.

oldbikerdude37 · Jun 20, 2011

Here is a good video by Tormach CNC

YouTube - ‪Using an Edge Finder - Tormach CNC‬‏

sorry they dont say crap..

Mcgyver · Jun 20, 2011

Cole2534 said:
So how does it work?

the conical, and for that matter the cylindrical end as well, can be used with the machine off and feel for when there is alignment with the body. Accuracy within a thou or two. Use the conical end in a centre punch mark, centre drilled hole, spotted hole, bore, pilot hole....you get the idea. If its needs greater accuracy use an indicator directly or with a wiggler

PaulM · Jun 20, 2011

Not sure if this is how they should Really be used but this is what I have done.

Issue is with a regular edge finder you have it spinning and wait for it to kick out. With the pointy end and a hole you can't do that. What I have done is with the machine off lower the point into a center punch or hole (light pressure), then use your x and y adjustments to center the point section to the rest of the shaft. I generally go by feel as you can feel a couple thou.

Is not a centering scope and there may be better ways but it has worked well enough the couple times I did it.

If this is wrong I'm sure someone with more experience will chime in shortly.

Paul

Conrad Hoffman · Jun 20, 2011

Yes, there is no snap with the conical end. I just run my fingernail across the joint while moving X and Y until I don't feel a step.

gwilson · Jun 20, 2011

I only ever use the conical tip to center a punch mark,but my Blake co-ax indicator is easier. I put the conical tip in the punch mark,center it ass well as possible,then measure the diameter of the center finder over the joint of the body and the tip. Measure with a mic in 2 places at 90º to each other,moving the mill table until I get both diameters the same. Hope that makes sense.

The cone is also useful in centering keyways. I don't know all its secrets,just measure with a mic until it is the correct .500" diameter across the keyway.

atomarc · Jun 20, 2011

Mcgyver said:
the conical, and for that matter the cylindrical end as well, can be used with the machine off and feel for when there is alignment with the body. Accuracy within a thou or two. Use the conical end in a centre punch mark, centre drilled hole, spotted hole, bore, pilot hole....you get the idea. If its needs greater accuracy use an indicator directly or with a wiggler

That is how I have used the conical finder too but thought it was pretty archaic...I have a wiggler but haven't used it because again, I have no real idea how it works or why it might be more accurate than the funky conical center finder. :eek:

Stuart

Cole2534 · Jun 20, 2011

Mcgyver said:
the conical, and for that matter the cylindrical end as well, can be used with the machine off and feel for when there is alignment with the body. Accuracy within a thou or two. Use the conical end in a centre punch mark, centre drilled hole, spotted hole, bore, pilot hole....you get the idea. If its needs greater accuracy use an indicator directly or with a wiggler

Man, I feel dense. It's never before occurred to me to use the EF with the machine off. :nutter:

Mcgyver · Jun 20, 2011

atomarc said:
That is how I have used the conical finder too but thought it was pretty archaic...I have a wiggler but haven't used it because again, I have no real idea how it works or why it might be more accurate than the funky conical center finder.

Stuart

lol, was thinking, indicating holes, then indicating a point in the lathe with wiglgler/indicator

. it would do zero good in the mill, not sure what i was thinking or I guess i just wasn't.

John Garner · Jun 20, 2011

I use the pointy end when positioning a spindle axis over a scribed line, or, more usually, over the intersection of a scribed-line pair.

To center the pointy tip on the spindle axis, I fire up the spindle and then touch the side of the spinning cone with a steel rule, pencil, or tip of a finger until it runs true. Then, after stopping the spindle, I watch thisaway -- ALONG the scribed line -- while moving the work (or spindle) thataway -- perpendicular to the scribed line, until the tip is centered over the line. Then, if centering a scribed-line intersection, I watch thataway -- ALONG the OTHER scribed line -- while moving the work (or spindle) thisaway -- perpendicular to the line I'm watching -- until the second scribed-line is centered.

atomarc · Jun 20, 2011

John Garner said:
I use the pointy end when positioning a spindle axis over a scribed line, or, more usually, over the intersection of a scribed-line pair.

To center the pointy tip on the spindle axis, I fire up the spindle and then touch the side of the spinning cone with a steel rule, pencil, or tip of a finger until it runs true. Then, after stopping the spindle, I watch thisaway -- ALONG the scribed line -- while moving the work (or spindle) thataway -- perpendicular to the scribed line, until the tip is centered over the line. Then, if centering a scribed-line intersection, I watch thataway -- ALONG the OTHER scribed line -- while moving the work (or spindle) thisaway -- perpendicular to the line I'm watching -- until the second scribed-line is centered.

John,

I have a piece of 1/2" drill rod that I've ground to a sharp point. I do the same routine you described to align the quill above a line or punch point...but I don't have all the monkey motion of the little moveable tip to deal with. What's the difference? Why the moveable conical point?

Stuart

Finegrain · Jun 20, 2011

atomarc said:
John,

I have a piece of 1/2" drill rod that I've ground to a sharp point. I do the same routine you described to align the quill above a line or punch point...but I don't have all the monkey motion of the little moveable tip to deal with. What's the difference? Why the moveable conical point?

So you can feel the offset of the 1/2" barrel above and below the split. Bury the tip in the punch mark, then feel the barrel and see that the upper and lower aren't lined up. Adjust until you can't feel the joint.

Regards.

Mike

Conrad Hoffman · Jun 20, 2011

That seems perfectly reasonable but I can't help but wonder if somebody at the Acme Edge Finder Company said, "man, how can we charge a higher price for these things?" and the response was, "let's put a pointed tip on the other end and see if anybody's willing to pay more. We'll call it the deluxe version." Because everybody knows how the edge finder part works, you'd just expect some similar clever use of the pointed end, but nooooo... you just stick it in a divot and slide the table around until it's centered.

atomarc · Jun 20, 2011

Conrad Hoffman said:
That seems perfectly reasonable but I can't help but wonder if somebody at the Acme Edge Finder Company said, "man, how can we charge a higher price for these things?" and the response was, "let's put a pointed tip on the other end and see if anybody's willing to pay more. We'll call it the deluxe version." Because everybody knows how the edge finder part works, you'd just expect some similar clever use of the pointed end, but nooooo... you just stick it in a divot and slide the table around until it's centered.

My sentiments exactly.......

Stuart

John Garner · Jun 21, 2011

Stuart --

The "monkey motion" allows the tip to be centered on the spindle's axis of rotation even if the chuck or collet doesn't do a good job centering the shank.

John

Cole2534 · Jun 22, 2011

atomarc said:
My sentiments exactly.......

Stuart

To a lesser extent- why different sizes of edge finders? Metric (whatever size that is), and .200" seem perfect.

What the hell is someone going to do with a .500" diameter edge finder they can't do easier with a .200"?

Conrad Hoffman · Jun 22, 2011

Actually the larger finder do have a use- when you have to hit the side of some big round thing where the edge on the little one hits before the .2 part. I also like .5 bodies and .375 bodies, depending on collets and chucks in use. Finally, I once saw somebody use an edge finder upside down to get to a real low area. You have to go very slow, but it works just fine.

Using a center finder?

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