Clamp on gage in reverse order?

[SeasonLee]

In an open setup measuring, the datum system communicates important inspection instructions, we will clamp the part based on the sequence (order)---Primary-Secondary-Tertiary to simulate the functional conditions during measuring.

But, when we clamp the part on a gage, always clamp in reverse order---Tertiary-Secondary-Primary. I read it on a post in LinkedIn discussion, why in reverse order?

Have a great X’mas Holiday

Season

 

[3DDave]

Link to LinkedIn discussion?

Unless there is more to it, it doesn't seem sensible.

 

[SeasonLee]

Here is the link

Season

 

[3DDave]

Read it - seems senseless. Some other topics there suffer from the same problem. Rather than read the spec and follow it, people make up stuff and guess. Maybe it's just a sophisticated version of the Liar's club.

Trick question: Where in the standard is Geometric Dimensioning defined? Extra points for 1982, 1994, and 2009 specifics.

 

[Belanger]

Why was "clamping" suddenly brought up in that discussion? I think that itself introduced confusion.
Recall that the standard says free state is the default condition unless a restraint note is added to a print. So merely saying that something is primary-secondary-tertiary has nothing to do with clamps.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[greenimi]

From Mark Foster ---Applied Geometrics---(different thread, but I think applicable on what we are trying to talk about here---order of clamping)
IMHO first 2-3 sentences are applicable here.

Begining of Mark's post:

Your "Go" gage should FIRST, simulate the datum reference frame -- that is, it should establish the part in its correct (specified) coordinate system; and then SECOND it should see if there is no material where there is not supposed to be material (i.e. the "go" gage should "go").

Then the "No-Go" gage should FIRST, simulate the datum reference frame, and SECOND it should see if there is material where there is supposed to be material (i.e. the "no-go" gage should "not go").

Your gage elements for simulating your datum features on the part should be the virtual condition sizes of the datum features, and must always go, and then by the amount that the actual datum features have departed from those virtual condition boundaries, you are allowed to "wiggle the part" (i.e. take advantage of the datum shift permitted by the MMB modifiers on the datum reference frames of the profile callouts) until you can make the "go" gage "go."

And you should never be able to make the "no-go" gage "go" no matter how much wiggling you do of the datum reference frame.
End of Mark's post

 

[SeasonLee]

greenimi
Would you please provide the link.
Have a great X'mas holiday

Season

 

[greenimi]

http://groups.yahoo.com/neo/groups/Y14-5_User_Group/conversations/topics/3883

Yahooo user group
Y14-5_User_Group

Thread name:
Functional gage for a profile
Date: January 10, 2012

Original post:
"Can a functional gage be design to check the bilateral profile? DRF is at MMB.
Go gage to verify the outer profile and a nogo gage to verify inner profile? Will this concept work, at least in theory?
Datums are FOS at are at the MMC----MMB in 2009-
We use Y14.5-1994 Thank you"


Merry Christmas!