Run out

[[Mi...]]

SO I got this part that I am checking runout from an ID to an OD feature.

I make the ID a cylinder (datum) using Min Circumscribed and the OD feature a circle using LSQ. This follows along with what my good ol cook book says.

Eng here says it should be LSQ on cyl as well as the circle. I don't work much with run out so any help is appreciated.

Im sticking with the cookbook lol.

[[Br...]]

Well the Cookbook shouldn't say to use Minimum Circumscribed for an ID. Should say Maximum Inscribed. Or you can use outer tangential. Anyway, It all has to do with how the datum feature is simulated. Per Y14.5, a cylindrical feature as a primary datum feature at RMB, has a datum simulator that is the Unrelated Actual Mating Envelope. For an internal cylindrical feature like you have the standard says the datum simulator is "... largest inscribed (for an internal feature) perfect cylinder that makes maximum possible contact with the datum feature surface."

A maximum inscribed fitting algorithm (or OuterTangential) will fit this criteria.

[[Mi...]]

Gotcha.

But yeah the CB states use the MCCY on the cylinder and the circle as LSQ. Closer reading its using RO to a shaft from a shaft as the example.

Also working with ISO on this part

When I change it over to outer tang, doesn't really change the results. They are still out. He's fishing

[[Br...]]

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Right, If the Datum Feature was an external feature then you would want to use Minimum Circumscribed. OuterTangiential should give you the exact same results as Max Inscribed in your case though. It effectively runs the exact same algorithm. Also ISO and ASME should be in complete harmony with regard to this measurement. I just cant quote you what the ISO standard says about this.

[[Mi...]]

Going back and changing things on the Cyl ID I get...

Outer and Min give me the same result

Inner and Max give me the same result

Max and Outer give me 2 different results... I have set them all to Max Insc though

[[Br...]]

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Then either there is something you're not telling me or there is a massive bug in your version of Calypso because it should be the opposite for an internal feature. You might want to get with Zeiss because you can't inspect parts that way. Just do it on a simple diameter characteristic and see if you get the same result. Outer Tan and Max Inscribed will give you the smallest inscribed diameter of internal feature. Inner tangential and Min Circumscribed with give you the opposite on an internal feature.

[[Mi...]]

Figured it out. I was calling out the wrong datum on the 2nd and 3rd OD's.

As you stated Mr. Brett I get the matching numbers now.

All is well in the universe...….