# How to use a center finder



## prasad (Nov 19, 2014)

Guys, 

I have an edge/center finder from LMS. I have seen the video on hor to use it as a edge finder. Is there any video on how to use it to find the center? Any guidance is welcome. 

Regards
Prasad


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## george wilson (Nov 19, 2014)

Do you refer to a conical center finder on one end of an edge finder? Everyone seems to use theirs differently for centering up punch marks and small holes.

Tony Wells,the administrator,and a machine shop owner, gets his punch mark close enough that he can stick the center point into it. Then,he moves the X and Y axis until his fingernail doesn't catch on the mating edges of the center finder at positions 90º apart.

Then,he considers the punch mark to be accurately located on center with the spindle.

I get mine centered until I can measure across the mating joint with a micrometer at 2 places 90º apart,and get .500" on either side. Then,I consider the punch mark on center.

I hope this makes sense.


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## JimDawson (Nov 19, 2014)

Thanks George.  I never thought about the mic method.  I've always used my fingernail like Tony.


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## george wilson (Nov 19, 2014)

I might be being excessive about it,but that's what I do. The fingernail probably works fine if Tony uses it. I'll try it next time,then,after I get the center satisfactory with the nail,I'll check with a mike. Be sure to hold the mike exactly vertical to the edge of the center finder. Careful technique is necessary.


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## Jamiethesquid (Nov 20, 2014)

So I may be a little bit numb, but I am assuming that the spindle is not on while using the center finder unlike when using the edge finder.


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## JimDawson (Nov 20, 2014)

Yes, you are correct, this is done with the power off.  I should say that there is a way the use the pointy end under power to find a center of a larger hole, but I have never done it.


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## Andre (Nov 20, 2014)

When feeling for the two pieces of the edgefinder to line up, I have tried my fingernail, even razor blades to catch that lip. The best way I have found if to use your fingertips, much more sensitive than the nail. Even beats the razor blade edge catch test. With practice you can get centered over a punch mark to half a thou.


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## Smithdoor (Nov 20, 2014)

This one I use will hold to .001 I have others for .0001
come over and I will help you

Dave


http://www.shars.com/products/view/7552/Wiggler_Edge_Center_Finder_Set


prasad said:


> Guys,
> 
> I have an edge/center finder from LMS. I have seen the video on hor to use it as a edge finder. Is there any video on how to use it to find the center? Any guidance is welcome.
> 
> ...


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## prasad (Nov 26, 2014)

Hi 

Many thanks. I tried Tony's method and was able to center the part in my 4-jaw chuck. I am now boring it. I am trying to make a Dremel tool holder for my Grizzly 9x19 lathe. I hope I will not make any mistakes. 

I have to try your micrometer method soon.

Thank you all who replied to this thread. 

Prasad
Wynnewood PA






george wilson said:


> Do you refer to a conical center finder on one end of an edge finder? Everyone seems to use theirs differently for centering up punch marks and small holes.
> 
> Tony Wells,the administrator,and a machine shop owner, gets his punch mark close enough that he can stick the center point into it. Then,he moves the X and Y axis until his fingernail doesn't catch on the mating edges of the center finder at positions 90º apart.
> 
> ...


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## prasad (Nov 27, 2014)

Here is the reason for my question. I wanted to make a Dremel tool holder for my 9x20 lathe. Using guidance received I centered the job on my lathe chuck and made the tool holder. Pictures are attached. 

Thank you for all the help. 

Regards and happy turkey day, 
Prasad 
Wynnewood PA


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## CoopVA (Nov 27, 2014)

prasad said:


> Here is the reason for my question. I wanted to make a Dremel tool holder for my 9x20 lathe. Using guidance received I centered the job on my lathe chuck and made the tool holder. Pictures are attached.
> 
> Thank you for all the help.
> 
> ...



I like that!  Great idea...


Sent from my iPad using Tapatalk


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## JimDawson (Nov 27, 2014)

Nice job!


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## Tony Wells (Nov 27, 2014)

For that application there is another method of choice for me. I'll try to set it up for a photo if I get a chance, but here's a description:


Take a small diameter drill rod or similar with a accurately concentric cone ground on the end. This rod should be around a foot long (adjust for lathe size). Put the non-pointed end in a drill chuck in the tailstock, and get the point in the center punch but just barely tight. Now put a dial indicator as near as possible to the pointed end of the rod. The length of the rod will allow it to flex and follow whatever error there is with the punch mark. If it is way out, you should back off the tailstock a bit as you go because the effect on the rod is to lengthen as it runs truer. You don't want to push hard enough to bow it.


Alternatively, you can chuck the center finder lightly and again, place the point in the punch mark and use an indicator on the collar just above the point so that the indicator follows the point. You aren't really interested in the runout of the body, just the pointed section that is following the punch mark. Only gentle pressure should be used to engage the center finder.


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## prasad (Nov 27, 2014)

Tony Wells said:


> For that application there is another method of choice for me. I'll try to set it up for a photo if I get a chance, but here's a description:
> 
> 
> Take a small diameter drill rod or similar with a accurately concentric cone ground on the end. This rod should be around a foot long (adjust for lathe size). Put the non-pointed end in a drill chuck in the tailstock, and get the point in the center punch but just barely tight. Now put a dial indicator as near as possible to the pointed end of the rod. The length of the rod will allow it to flex and follow whatever error there is with the punch mark. If it is way out, you should back off the tailstock a bit as you go because the effect on the rod is to lengthen as it runs truer. You don't want to push hard enough to bow it.



I understand your idea but where can one get a long drill rod with a conical end?. I am using a Chinese made lathe with no-good or questionable precision, I can not make a perfect (or near decent) conical end. 

Please understand I am a beginner and not criticizing. I want to understand every possible answer to my question. 

Thanks
Prasad
Wynnewood PA


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## Skarven (Nov 28, 2014)

prasad said:


> I understand your idea but where can one get a long drill rod with a conical end?. I am using a Chinese made lathe with no-good or questionable precision, I can not make a perfect (or near decent) conical end.
> 
> Please understand I am a beginner and not criticizing. I want to understand every possible answer to my question.
> 
> ...



You could use your new Dremel toolholder to grind a near perfect cone on the end of a drill rod.  Set a non-critical angle on your compound and get the dremel height right, and you should be OK.

The toolholder is nice! Good work. I will also make one, shamelessly copying your design!

Kai


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## prasad (Nov 28, 2014)

Tony Wells said:


> For that application there is another method of choice for me. I'll try to set it up for a photo if I get a chance, but here's a description:
> 
> 
> Take a small diameter drill rod or similar with a accurately concentric cone ground on the end. This rod should be around a foot long (adjust for lathe size). Put the non-pointed end in a drill chuck in the tailstock, and get the point in the center punch but just barely tight. Now put a dial indicator as near as possible to the pointed end of the rod. The length of the rod will allow it to flex and follow whatever error there is with the punch mark. If it is way out, you should back off the tailstock a bit as you go because the effect on the rod is to lengthen as it runs truer. You don't want to push hard enough to bow it.



Tony

I have a few centerless ground rods 0.375" in diameter and about 10 inch long. Will it suit? 

Thanks
Prasad


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## prasad (Nov 29, 2014)

Skarven said:


> You could use your new Dremel toolholder to grind a near perfect cone on the end of a drill rod.  *Set a non-critical angle on your compound* and get the dremel height right, and you should be OK.
> 
> The toolholder is nice! Good work. I will also make one, shamelessly copying your design!
> 
> Kai



Kai, 

Thank you but what do you mean by *non-critical angle*? I did not understand that part. 

Thank you
Prasad
Wynnewood PA


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## Thoro (Nov 29, 2014)

What was the thread specs you used to fit to your dremel?  When I made one of those jobbers a year or so ago I decided that trying to thread it was going to be a PITA so I bored it, then slit it, drilled, tapped and counterbored it for a cap head screw....making a clamp in effect.  Probably would have been less work to thread it in hindsight....


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## Tony Wells (Nov 29, 2014)

prasad said:


> Tony
> 
> I have a few centerless ground rods 0.375" in diameter and about 10 inch long. Will it suit?
> 
> ...




Prasad, a more slender rod would be better. You want it to flex as the out-of-center punch mark moves around a circular path as you rotate the chuck. I would use nothing larger than around 3/16". Then, use your indicator up close and personal to the part you are dialing in.

If you have a good running chuck, or a collet (even better), you can grind a point on your centering rod. Just mimic the angle of a live center as you would use in a tailstock. But it doesn't have to be exact. Just as long as it will seat well enough in your punch mark.


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## prasad (Nov 30, 2014)

Thoro said:


> What was the thread specs you used to fit to your dremel?  When I made one of those jobbers a year or so ago I decided that trying to thread it was going to be a PITA so I bored it, then slit it, drilled, tapped and counterbored it for a cap head screw....making a clamp in effect.  Probably would have been less work to thread it in hindsight....



Hi Thoro, 

Dremel thread size is 3/4" at 12 TPI. The bore was machined to 0.67" before starting internal thread cutting.  I used a 1"x1/2" aluminum flat 4 inches long which was later milled to 1/2" square shank. 

Hope this helps, 
Prasad
Wynnewood PA (Near Philly)


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## prasad (Nov 30, 2014)

Tony Wells said:


> Prasad, a more slender rod would be better. You want it to flex as the out-of-center punch mark moves around a circular path as you rotate the chuck. I would use nothing larger than around 3/16". Then, use your indicator up close and personal to the part you are dialing in.
> 
> If you have a good running chuck, or a collet (even better), you can grind a point on your centering rod. Just mimic the angle of a live center as you would use in a tailstock. But it doesn't have to be exact. Just as long as it will seat well enough in your punch mark.



Thank you Tony, I like this idea better than using the feeling center finder with a finger. I will order 1/8" drill rod on McMaster and it is very affordable. Yes, I do have a decent 4-jaw chuck and I will use my new Dremel tool holder for grinding the cone end. 

Thanks again, 
Prasad 
Wynnewood PA


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## visenfile (Nov 30, 2014)

Noob here understands some of this discussion...but.  Is this discussion restricted to lathe?  I do not have one but am familiar with punches and drilling vertically.  So is the lathe so rigid that e.g., after determining that the punch mark is off , the lathe driller can drill to the desired point adjacent to the punch mark?  With my lowly drill press and mill-drill I am familiar with the tendency of a drill to walk into the mislocated punch mark.  I am fairly good at moving the punch mark to compensate for mislocation of original punch mark.  Hope I have not spoken off topic.


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## EmilioG (Nov 30, 2014)

george wilson said:


> Do you refer to a conical center finder on one end of an edge finder? Everyone seems to use theirs differently for centering up punch marks and small holes.
> 
> Tony Wells,the administrator,and a machine shop owner, gets his punch mark close enough that he can stick the center point into it. Then,he moves the X and Y axis until his fingernail doesn't catch on the mating edges of the center finder at positions 90º apart.
> 
> ...



This sounds good. I'll try it. Now, except for the quill, do you lock the table?


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