What is Min_Sep for?

[Hirxm]

EDIT: It’s an internal cylinder.

I’m trying to measure the “smallest diameter” on an cylinder at 4 different levels which are created by scanning. However, PC-Dmis doesn’t let me use the Minimum Circumscribed option apparently because it is an auto feature and it only lets me use the Minimum Separation (Min-Sep).

Is this Min-Sep option useful for obtaining the smallest diameter? If not, is there any other way to do so?

[Mike Ruff]

If it's an ID you need to use MAX_INSCRIBED to get what you are after. Read up on the help files for explanations of how the different fitting algorithms work and when to use them

[Hirxm]

Do you mean Internal Diameter with ID? Sorry i’m pretty new to pc-dmis

[Schrocknroll]

It seems a little counter intuitive when you first hear it, but as Mike said, the smallest circle inside an I.D. is the Max Inscribed. Think of it this way, if it's a.500 I.D. you could fit a .250 pin inside it or a .100 or smaller. What you actually want to know is what is the largest pin that will fit inside the bore. That is the smallest size that will still touch at least three places in the bore. Thus the maximum circle you can inscribe inside the points taken.

[Hirxm]

oh my gosh I get it now, thank you so much Jeff and Mike!!

[JEFMAN]

And just answering your question, SEP_MIN is a minimax algo, which is used to calculate the cylinder (here !) which has the minimum form defect. (algo which is used to calculate the cylindricity or the circularity)

[JEFMAN]

And while you're using those algo, I think you should read this thread...

https://www.pcdmisforum.com/forum/pc-dmis-enterprise-metrology-software/pc-dmis-for-cmms/449320-disagree-with-the-algo-used-for-max-inscr-and-min-circ-cylinders

[JEFMAN]

And also this one , the #28 :

https://www.pcdmisforum.com/forum/pc-dmis-enterprise-metrology-software/pc-dmis-for-cmms/448108-2019-r1-spx-issues/page2