# "Indicating" round objects in the vertical mill



## popnrattle (Mar 2, 2012)

This video shows how I find the center of round parts using my edge finder and the DRO. Hope this helps make your machining project easier. Later, Rick.

[ame]http://www.youtube.com/watch?v=NCEASFdccXc[/ame]


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## crab (Mar 2, 2012)

Thanks,Bill


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## chuck foster (Mar 2, 2012)

that was a great little video...........thanks 

chuck


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## mklotz (Mar 3, 2012)

What you're doing is referred to as the "Osborne maneuver". It's detailed in one of Lautard's Bedside Readers. A program demonstrating its very rapid rate of convergence is available on my page - look for OSBORNE.ZIP.


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## popnrattle (Mar 3, 2012)

Hello, I read the text file about how the "osbourne maneuvre" worked. It stated you measure the diameter of the part and move over half that dimension and guess where the 3 o'clock postion is. 
   With my video procedure you can ignore the circle diameter(hole or shaft). You just take the average of 2 DRO readings. The average of zero and whatever the DRO value is with the edge finder on the other side. For example, if you are at 2 o'clock when you do the first edge it will automatically be at the 10 o'clock position when you do the other side, etc. Thanks for the input. Later, Rick.


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## mklotz (Mar 3, 2012)

Ahhh, the average of zero and "whatever the DRO value is with the edge finder on the other side" *is* half the diameter.


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## popnrattle (Mar 22, 2012)

Not exactly. It is not the diameter of the part you are indicating. Half of the value of the X-axis reading is the amount you move back to get to the center. I think you brainy guys are trying to over-think it. ;D Later, Rick.


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## kvom (Mar 22, 2012)

The DRO on the opposite side is the diameter of the part plus the diameter of the edge finder (at least on the final measurement).


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## b.lindsey (Mar 22, 2012)

Only if you measure at the 9 o'clock and 3 o'clock positions. As long as your y-axis readout remains the same for both readings, you would still be equidistant from the centerline, but at 10'o clock and 2 o'clock, the x axis reading would be less than the diameter (plus the edge finder dia.). 

Bill


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## Holt (Mar 22, 2012)

b.lindsey  said:
			
		

> but at 10'o clock and 2 o'clock, the x axis reading would be less than the diameter (plus the edge finder dia.).


This is a bit dangerous, the edgefinder wont "swipe out" at the same time going "uphill" as "downhill" unless you go backwards on one of the sides (does this make any sense?)


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## b.lindsey (Mar 22, 2012)

It does make sense Holt, but i think in practice most of us would eyeball closer to 9 & 3 o'clock to start with to minimize that effect. But your point is well made. Personally if I am doing something critical I still feel more confident using a DTI or coax indicator, but this method would certainly work.

Bill


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## purpleknif (Mar 22, 2012)

Uh... why not just buy an "Interapid type indicator ?


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## popnrattle (Mar 22, 2012)

Yeah, sometimes I do reverse the spindle direction to go "uphill/downhill both ways" but haven't really seen an advantage. Maybe I do it just to make the universe a little less out of whack! ;D


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## Omnimill (Mar 23, 2012)

If you had one would it be quicker or easier to use one of these on the hole instead?


http://www.grainger.com/Grainger/MITUTOYO-Edge-Finder-1ZRN5

Just thinking out loud, and whether I should buy one myself!

Vic.


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