GD&T Bonus Tolerance

Liger · #1 6th August 2012, 04:49 PM

I am checking true position of a pierced hole back to two other datum holes that are used at MMC. The inspection is being done using PCDMIS software, and for some reason, the bonus tolerance from only one of the datum holes is being applied. Should we not get the MMC bonus tolerance from both holes added together? Spec is: .034TP to D(M) and E(M). My PCDMIS report shows bonus tolerance of .0015 for D and .005 for E, but is only applying the .0015 as the total allowable bonus. Since the drawing gives both datums at MMC, should we not be receiving the total .0065"?

**Stijloor** · #2 6th August 2012, 05:09 PM

Quote:

In Reply to Parent Post by Liger

I am checking true position of a pierced hole back to two other datum holes that are used at MMC. The inspection is being done using PCDMIS software, and for some reason, the bonus tolerance from only one of the datum holes is being applied. Should we not get the MMC bonus tolerance from both holes added together? Spec is: .034TP to D(M) and E(M). My PCDMIS report shows bonus tolerance of .0015 for D and .005 for E, but is only applying the .0015 as the total allowable bonus. Since the drawing gives both datums at MMC, should we not be receiving the total .0065"?

We can help you, but to avoid all confusion, please attach a sketch of the call-out including the datum references. You can not arbitrarily add a bonus from both holes to the controlled hole. Datum shift is not an easy concept and is often misinterpreted.

Liger · #3 7th August 2012, 07:12 AM

Thank-you for your reply Stijloor. Hopefully I got the attachment on this response.

**Stijloor** · #4 7th August 2012, 07:19 AM

Quote:

In Reply to Parent Post by Liger

Thank-you for your reply Stijloor. Hopefully I got the attachment on this response.

The attachment shows the callout, but not the datum features.
Can you attach the actual drawing with confidential information removed?

Liger · #5 7th August 2012, 10:01 AM

Quote:

In Reply to Parent Post by Liger

I am checking true position of a pierced hole back to two other datum holes that are used at MMC. The inspection is being done using PCDMIS software, and for some reason, the bonus tolerance from only one of the datum holes is being applied. Should we not get the MMC bonus tolerance from both holes added together? Spec is: .034TP to D(M) and E(M). My PCDMIS report shows bonus tolerance of .0015 for D and .005 for E, but is only applying the .0015 as the total allowable bonus. Since the drawing gives both datums at MMC, should we not be receiving the total .0065"?

My apologies. See if this helps.

**Stijloor** · #6 8th August 2012, 03:05 AM

A Quick Bump!

Can someone with CMM/PCDEMIS expertise help with this?

Thank you very much!!

thiyagarajani · #7 6th March 2013, 02:54 AM

now i am facing same problem . pls clear this

Dooglas · #8 15th April 2013, 04:00 PM

I have attached a portion of a customer drawing that defines some positional characters for hole locations. The general tolerance is ±.015 inches but I am unclear how to interpret the tolerance provided concerning the locations of the (88) Ø.390 holes and the (8) tapped holes.
I also have to report dimensional results in my PPAP reports and want to make sure I report this properly. Any help would be appreciated.

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