Adding MMC to Position Characteristic

[[Ra...]]

See attached. The alignment is symmetry plane of -A- and -B- and then -C- point tertiary. Question I have have is how to get the MMC into the True postion characteristic for -A- (11.6 width) and -B- (16.2 width) regarding the 9.4mm thru hole? I currently have the symmetry of -A- plane as primary and symmetry of -B- plane as secondary.  MMC is not an option in the characteristic with the symmetry plane alignment. Thanks!

 

 

[[Cl...]]

Constructing a Symmetry plane should allow you to us MMC.

[[Jo...]]

The Symmetry plane does allow MMC if it is the feature for evaluation, but the software doesn't allow MMB on the DRF. 

I'm not even sure MMB on Datum A would even do anything since it is parallel to the axis of the bore. 

 

 

[[Ra...]]

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Yeah I was a little puzzled at the GD&T in that regard

[[Jo...]]

I thought I had a workaround for you that I had seen before, but the software still doesn't allow it. 

The workaround was to create a perpendicular for each datum, then create two theoretical circle features and use PCM to right-click on the diameter box and add the get actual for the length of the perpendiculars. 

The thought was that it would allow you to add the modifiers to the circles, but it is still grayed out 😞

[[Ch...]]

if I had to absolutely do this, I would end up creating a theoretical cylinder for -A- with data that matches the symmetry plane, and probably require a best fit position to get MMC of A, I think I have done it a few times actually.

[[Ch...]]

Id be curious if this works with symmetry plane MMC/MMB with the 2025 GDT Engine

[[Ri...]]

Yes

[[Ro...]]

Why not use a formula for the MMB?  Take -A- width and -B- width for use in the formula.

[[Ri...]]

Because that's not how MMB/LMB works. 

 

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[[Ma...]]

That's something i'll try on monday.

Symmetry plane should give MMB - constructed symmetry from planes won't.