# Packed Away The Edge Finders



## papermaker (Jul 7, 2014)

I think the days of changing tool holders just to use the edge finder are over. I was looking for plans for a touch probe for my CNC mill and didn't really find anything to my liking. What I did stumble across was information where someone used a multimeter to establish the the edge of a project. 

I used this method today on a project that I was making and it was nuts on. It couldn't have been simpler to use.
You set your multimeter to it's lowest setting to measure ohms. Then you attach one of the leads to the table.( it doesn't matter which lead you use). Then hold the other lead against the cutting tool. If you are using an end mill be sure the widest part of the flute will touch the work. The ohm meter should read under 2 ohms. Advance the work toward the tool slowly and watch the ohm meter. When the tool touches  the work the ohms will drop to around .2 or .3 ohms. You have now found the edge of the work. From that point it works basically like a regular edge finder. 
I cut my set-up time and I wasn't constantly looking for wrenches and edgefinders. Hope this helps someone else.


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## ScrapMetal (Jul 8, 2014)

That's pretty much brilliant in a simple kind of way.  Kudos to whoever came up with that one and thank you for sharing.  I'll be trying that out with my DMM tomorrow.

-Ron


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## fixit (Jul 8, 2014)

papermaker said:


> I think the days of changing tool holders just to use the edge finder are over. I was looking for plans for a touch probe for my CNC mill and didn't really find anything to my liking. What I did stumble across was information where someone used a multimeter to establish the the edge of a project.
> 
> I used this method today on a project that I was making and it was nuts on. It couldn't have been simpler to use.
> You set your multimeter to it's lowest setting to measure ohms. Then you attach one of the leads to the table.( it doesn't matter which lead you use). Then hold the other lead against the cutting tool. If you are using an end mill be sure the widest part of the flute will touch the work. The ohm meter should read under 2 ohms. Advance the work toward the tool slowly and watch the ohm meter. When the tool touches  the work the ohms will drop to around .2 or .3 ohms. You have now found the edge of the work. From that point it works basically like a regular edge finder.
> I cut my set-up time and I wasn't constantly looking for wrenches and edgefinders. Hope this helps someone else.






SEE http://rick.sparber.org/meef.pdf


fixit


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## Don B (Jul 8, 2014)

fixit said:


> SEE http://rick.sparber.org/meef.pdf
> 
> 
> fixit



That's wonderful, thank you very much....!)

Edit: Have you tried this yourself ?


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## fixit (Jul 8, 2014)

Don B said:


> That's wonderful, thank you very much....!)
> 
> Edit: Have you tried this yourself ?




No, it's not high on my list. But this guy does an outstanding job of design & expiation of many porjects.

fixit


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## papermaker (Jul 8, 2014)

That's the link! Thanks for finding it and posting it here so the guy get recognition for coming up with a great method


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## Ripthorn (Jul 11, 2014)

This is basically how a touch off plate on a CNC works, you are just shorting a path is all.  You could even get one of the multimeters with a continuity function and it will beep at you when you have continuity (<5-10 ohms).  Note that some multimeters (cheap ones) will have a higher resistance simply due to the quality of the probes and the contact resistance of the paths.

Also note that this only works with metals and not plastics or wood.  Still, useful in most situations.


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## John Hasler (Jul 11, 2014)

papermaker said:


> I think the days of changing tool holders just to use the edge finder are over. I was looking for plans for a touch probe for my CNC mill and didn't really find anything to my liking. What I did stumble across was information where someone used a multimeter to establish the the edge of a project.
> 
> I used this method today on a project that I was making and it was nuts on. It couldn't have been simpler to use.
> You set your multimeter to it's lowest setting to measure ohms. Then you attach one of the leads to the table.( it doesn't matter which lead you use). Then hold the other lead against the cutting tool. If you are using an end mill be sure the widest part of the flute will touch the work. The ohm meter should read under 2 ohms. Advance the work toward the tool slowly and watch the ohm meter. When the tool touches  the work the ohms will drop to around .2 or .3 ohms. You have now found the edge of the work. From that point it works basically like a regular edge finder.
> I cut my set-up time and I wasn't constantly looking for wrenches and edgefinders. Hope this helps someone else.



This will work well on some machines.  On others, thought, the resistance back to the table through the spindle bearing is too low.


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## digiex_chris (Sep 9, 2014)

aww nuts, I'm not the first one to come up with this! :lmao:

I clued in when I realized the cross slide on my taig was anodized aluminum, and it would be non-conductive. I touch one lead to the chuck, one lead to the tool bit, and it beeps when it touches. As accurate as my hands on the knobs are.

When I got my larger lathe, there was too low of resistance through the machine. Different way oils changed things a little (thicker ones), but I had the best success when using a little strip of paper or plastic under the tool bit where it contacted the tool post.

I started doing the same thing on the milling setup, but using paper against the vise jaw faces, which also results in a firmer grasp on the part. Even soaked in cutting oil, it's enough of a change in resistance to see a resistance drop with the meter.


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## middle.road (Sep 9, 2014)

hmmmm, I've got a couple of old Simplexs laying in a drawer. Rainy day project? (and the list just keeps on growing....)

_Dan


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## TOOLMASTER (Sep 9, 2014)

1/2"-1/4" delrin bushing and a 1/4" metal rod
some wire..an led, 3 volt battery...project box


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## eightball (Sep 17, 2014)

Great idea, thanks


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