Surface Profile MMC

[[Cl...]]

Just a gripe. What doesn't Zeiss allow you to add MMC bonus for datum's within the surface profile characteristic?

SPROFILE.png

[[Aa...]]

If you're gonna gripe, you'd better be ready for some quibbling.

There is no "bonus" for MMC datum feature references (or MMB in Y14.5-2009). There is only datum feature shift/displacement.

But the fact that you can't reference datum features with boundary conditions for profile callouts is indeed a legitimate gripe.

[[Cl...]]

So the drawing is wrong?

[[Aa...]]

No, the snippet you posted looks perfectly legitimate.

But MMC/MMB on datum features doesn't give you "bonus tolerance". You only get bonus tolerance when the M symbol (or L symbol) precedes the datum reference frame. Actually, that's the reason the 2009 standard switched to calling it MMB instead of MMC--to highlight the distinction. When the M or L symbol follows a datum feature reference, it means something subtly different.

(Kind of like how powder-free latex gloves are not latex-free...)

[[Cl...]]

Isn't that what Calypso does with true positions that have MMC/MMB? It doesn't actually add the "bonus" tolerance to the given tolerance , but shifts the datum's around within the amounts gained?

[[Aa...]]

If the MMC/MMB is on datum features, then you're right. If the position FCF tolerance is MMC, then it adds the bonus tolerance.

Sorry if I somehow muddied the waters on this...

[[Al...]]

Modifiers cannot be used on Surface Profile. The drawing is wrong.

[[Aa...]]

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The drawing is not wrong. Profile tolerances may not be specified on a MMC or LMC basis. However, datum features may be referenced on a MMC/MMB or LMC/LMB basis for any kind of tolerance except runout (which is a horse of a different color, as far as the DRF goes).

[[Jo...]]

It depends on what datum feature A is. If it's a regular feature of size then it's fine and I don't know why Calypso won't let you select the MMC (MMB) on the datum reference. If datum feature A is a surface then while it's not illegal to do, it makes zero sense since the interface with the datum simulator is exactly the same.

[[Aa...]]

Good point, John. I simply meant there's nothing inherently wrong with the snippet we have in itself. I assumed A was a regular feature of size.