Composite position FRTZ bigger than PLTZ?

Tabor
Super User
Super User
Posts: 177
Joined: Thu Dec 20, 2012 3:43 pm

Composite position FRTZ bigger than PLTZ?

Post by Tabor » Fri Apr 08, 2016 12:37 pm

This is as much a GD&T question as it is a CMM-M question:

I'm measuring 2 holes that have a composite position of .028"/.010". The FRTZ is bigger than the PLTZ by almost .030" . How can that be?
Tabor

User avatar
US_Helpdesk
Moderator
Moderator
Posts: 1094
Joined: Wed Feb 23, 2011 7:26 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by US_Helpdesk » Wed Apr 13, 2016 11:32 am

Are the feature control frames different for top and bottom frame? If so, I suppose that could happen if there are less constraints on first frame. Although, this doesn't seem right to me. Can you send project or sample project to helpdesk?
I've migrated to a new user account, see my other posts here

Tabor
Super User
Super User
Posts: 177
Joined: Thu Dec 20, 2012 3:43 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by Tabor » Wed Apr 13, 2016 4:56 pm

It's a single feature control frame and I have the box unchecked. It is fully constrained for the PLTZ and 2 datums for FRTZ. I was reporting position from Datum Features. I changed it to Datum Ref Frame and it now works. I thought I knew the difference but this situation indicates I might need a refresher.
Tabor

User avatar
US_Helpdesk
Moderator
Moderator
Posts: 1094
Joined: Wed Feb 23, 2011 7:26 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by US_Helpdesk » Wed Apr 13, 2016 11:01 pm

I thought I had a PDF document somewhere on the Forum that describes this in detail...
I've migrated to a new user account, see my other posts here

Tabor
Super User
Super User
Posts: 177
Joined: Thu Dec 20, 2012 3:43 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by Tabor » Thu Apr 14, 2016 10:23 am

Tabor

User avatar
CrashN8
Site Admin
Site Admin
Posts: 282
Joined: Thu Feb 09, 2017 4:07 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by CrashN8 » Mon Nov 12, 2018 6:02 pm

Tabor wrote:
Thu Apr 14, 2016 10:23 am
Found it:
I accidently destroyed your link... Probably due to maintenance a few years back while rearranging forum posts. Here is info from CMM-Manager Help Files. Notice the difference in Separate vs. Combined Feature Control Frames.
composite_position.jpg
You do not have the required permissions to view the files attached to this post.

andycmm
Frequent User
Frequent User
Posts: 34
Joined: Wed May 17, 2017 11:11 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by andycmm » Thu Mar 07, 2019 2:47 pm

What is the math behind composite position? Our engineering doesn't trust CMM Manager because we are getting results where the the composite (bottom) result is larger than the top frame result. I am using "one feature control frame" with datum with just 2 holes.
You do not have the required permissions to view the files attached to this post.

andycmm
Frequent User
Frequent User
Posts: 34
Joined: Wed May 17, 2017 11:11 pm

Re: Composite position FRTZ bigger than PLTZ?

Post by andycmm » Tue Mar 12, 2019 10:12 am

Has anyone had a chance to look at this?

User avatar
medupriest
Moderator
Moderator
Posts: 349
Joined: Fri Mar 13, 2015 11:59 am

Re: Composite position FRTZ bigger than PLTZ?

Post by medupriest » Thu Mar 14, 2019 11:00 am

I am sorry for the delay on this. I have been looking into it, but so far, cannot reproduce the issue. Can you please email me the project file and a helpdesk file?

User avatar
medupriest
Moderator
Moderator
Posts: 349
Joined: Fri Mar 13, 2015 11:59 am

Re: Composite position FRTZ bigger than PLTZ?

Post by medupriest » Thu Mar 14, 2019 11:45 am

Run Data will also be needed, unless you have verified the features in the teach environment.

Post Reply