# Edge Finder Heads Up



## Ken I (Apr 3, 2012)

Since there is always some new and completely stupid thing you can discover every day I thought I would post this.

My mechanical edge finder has always been spot on repeatable but suddenly went out - serviced and cleaned it - no joy.

Then tested it against a piece of brass and it was fine. Against steel still useless...

AH-HA ! Eureka moment.

Tip had become slightly magnetized after coming into proximity of a very powerful Neodium magnet.

Whilst I figure out how to demagnetise it - I thought I would post this caveat:

Beware of magnetized steel parts and / or accidentally magnetising your edge finder - either will cause wildly faulty results.

Ken


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## b.lindsey (Apr 3, 2012)

Good observation Ken! If you know anyone locally that does precision surface grinding, there's a fair change they would have an industrial strength demagnetizing unit which might solve your problem.


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## purpleknif (Apr 3, 2012)

Try tapping it with a small hammer. (lightly)


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## jim216 (Apr 3, 2012)

If you have a loop type soldering gun ( Weller) ,try passing it through the loop. 


.


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## Ken I (Apr 3, 2012)

b.lindsey  said:
			
		

> Good observation Ken! If you know anyone locally that does precision surface grinding, there's a fair change they would have an industrial strength demagnetizing unit which might solve your problem.



Come to think of it I do know someone with a demagnetizer - thanks for jogging the old grey matter.

Jim thanks for that tip as well - I think you've posted that before but it had slipped my mind (more and more does these days).

Ken


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## mklotz (Apr 3, 2012)

When you visit your local electronics boneyard, keep your eye peeled for a bulk tape eraser. They work well for this and can handle parts that won't fit the soldering gun.


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## Tin Falcon (Apr 3, 2012)

http://www.sears.com/shc/s/p_10153_12605_SPM2203284501P?sid=IDx20070a921x00003a&ci_src=14110944&ci_sku=SPM2203284501
Cheap and readily available 
Tin


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## tornitore45 (May 10, 2012)

Tim Falcon, your link is interesting, I need one of them but is the opposite of what is needed to DEmagnetize the edge finder.


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## Tin Falcon (May 10, 2012)

Product Description

Screwdriver Magnetizer/Demagnetizer, Magnetizes and Demagnetizes Screwdrivers, Taps, Nutrunners, Etc. Clamshell Packaging.
Tin


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## Mainer (May 10, 2012)

Hmmm...I wonder if that explains why my Starrett edge finder isn't kicking as well as it used to.


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## Tin Falcon (May 11, 2012)

could just need a drop of oil
Tin


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## bezalel2000 (May 11, 2012)

Does any one have a good design for turning up a brass edge finder?

Bez


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## Mainer (May 11, 2012)

@Tiin:
I wish it was that simple. I've cleaned and oiled the mating surfaces with instrument-grade Nyoil. The action feels the same to my fingers as that of a new Starrett edge finder I bought. Yet, the new one kicks out strongly and the old one sort of grudgingly moves off-center. I think there is a certain amount of magic involved in the operation of edge finders.


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## Ken I (May 11, 2012)

Mainer,
     Edge finders can be fussy about the oil - I cleaned mine once and lubricated it with Automatic Transmission Fluid and it simply stopped working - you could push it way off centre and it would not kick over.

Cleaned it and lubricated with 3in1 and it worked fine again.

Go figure.

Ken


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## b.lindsey (May 11, 2012)

Bez, why brass? Non-magnetic yes...but i would think wayyyyy too soft for actual use.

Bill


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## mcostello (May 11, 2012)

I called Starrett years ago before start of the Internet and asked why their edge finder worked so smoothly. Asked what did they use for lubrication. STP was the answer, so with some scrounging at local Auto parts merchants, I found a can that some had used and the can still had some in it as it will not drain right away. Lifetime supply for free.


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## Lew Hartswick (May 11, 2012)

b.lindsey  said:
			
		

> Bez, why brass? Non-magnetic yes...but i would think wayyyyy too soft for actual use.
> 
> Bill


And a "brass" spring ?  
  ...lew...


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## lemelman (May 24, 2012)

How about one of the non-magnetic stainless steels?

Gary


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## Hopefuldave (May 24, 2012)

Quote from: b.lindsey on May 11, 2012, 08:14:20 AM
Bez, why brass? Non-magnetic yes...but i would think wayyyyy too soft for actual use.

Bill
And a "brass" spring ?  
  ...lew...


Aluminium bronze body, phosphor bronze spring? Non-magnetic and hard enough to take some use before it wears out?

I was wondering what to do with that little leftover stub... Hmmm, the shank to go in the chuck could be steel?
Anyone have a source for phosphor bronze wire in small lengths/gauges in the UK?

Dave H. (the other one)


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## abby (May 24, 2012)

Aluminium bronze is magnetic :


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## Hopefuldave (May 26, 2012)

abby said:
			
		

> Aluminium bronze is magnetic :



Ooer... I wonder what that bit of bar in the shed is, then? Hard, bronzy coloured, non-magnetic... 

I shall have to do some Chemistry, I suspect!

Dave H. (the other one)


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## bezalel2000 (May 27, 2012)

abby  said:
			
		

> Aluminium bronze is magnetic :



I'm not sure if that is a question or a statement. 

Either way, I think it is only true while it has an electric current flowing through it.

*Bill*  Thanks for the heads-up on the hard wearing requirement, I wasn't aware the rubbing would be that significant. 

I'm still interested in some shop build drawings if any one knows where they can be found.

Cheers

Bez


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## Blogwitch (May 27, 2012)

Just as a note of interest, edge finders like the Starrett design can now be found with ceramic tips, that should overcome the magnetic problems.

http://www.taiwantrade.com.tw/stw/p...er,_Ceramic_Edge_Finders,_Ceramic_Edge_Finder

John


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## abby (May 28, 2012)

Try a magnet on a piece of Aluminium bronze bar , this is how we check out this material in the scrap yard.


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## rotorhead (Jun 17, 2012)

Hi Folks,

Just a question, are edge finders more accurate than wigglers?


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## bp (Jun 18, 2012)

Rather than building a special non magnetic edge finder out of some unobtainium, why not go to your local friendly electronics shop and ask for a demagnetiser. Up here in 'Straya there's an electronics company called Jaynar, I noticed one in their catalogue for all of $6 and some cents, it was a 2009 catalogue though. 
I'm sure that we are not alone and these things will be available elsewhere.
cheers
Bill Pudney


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## Philipintexas (Aug 15, 2012)

MY error. I intended it to be a new subject,


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## Lew Hartswick (Aug 23, 2012)

Demagnitizers: I just tore apart a non functioning electric can opener and 
removed the drive motor, threw away the armature and "lo and behold" a 
no cost de-magnitizer.  Plug it in slowly pass the object (edgefinder screwdriver etc.) through the hole that use to have an armature in it and 
move the object away a good distance before turning of the power.


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## Hilmar (Aug 23, 2012)

"1970 Tape bulk eraser " from Radio Shack  .

Hilmar


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