|
|
| Mechanical Design, Manufacturing and Engineering Forum |
|
[ Home
] [ Search
] [ Engineering
and Design Database ] [ Product
and Services Directory ] [ Engineering Forum ] [ DFM DFA Training and Trainers ] [ GD&T Training GD&T Trainers ] [ Advertise ] |
| [ Archive#1 ] [ Archive #2 ] [ Archive #3] [ Calculators ] |
| Forum Moderators: randykimball, Administrator |
|
|
| GD&T Position Tolerance WRT Datum Order |  | ||
| Post Reply | Forum | ||
|
Posted by: gravynorth ® 06/08/2005, 10:33:44 Author Profile Mail author Edit |
I am looking for clarification, please... When specifying a positional tolerance of a hole, the primary datum in the feature control frame is always the datum that the hole is perpendicular to followed by the secondary and tertiary selected by the part function. For example: A rectangular part measuring 5W x 3H x 1D, I set my Datum A on the bottom (1D surface), Datum B along the horizontal (5W) surface and Datum C along the vertical surface. I am going to locate hole #1 through the part normal to the bottom (Datum A) and hole #2 through the part normal to the side (Datum C). In the feature control frame for hole #1 the primary datum (or the first datum listed in the FCF) would be A. In the feature control frame for hole #2 the primary datum (or the first datum listed in the FCF) would be C. I believe this is correct, but can someone please confirm or deny this? Any help will be greatly appreciated. Thanks! |
| Post Reply | Recommend | Alert | View All | | | |
| Replies to this message |
| Re: GD&T Position Tolerance WRT Datum Order |  | ||
| Re: GD&T Position Tolerance WRT Datum Order -- gravynorth | Post Reply | Top of thread | Forum |
|
Posted by: Kelly_Bramble ® 06/08/2005, 13:36:40 Author Profile Mail author Edit |
What you have said, that the primary datum is always the feature perpendicular to the hole axis, is a good general rule, however, this is not a absolute rule. A good way of thinking about datums are, the primary datum is the feature, which has the most influence on the resulting fit or alignment of the hole feature. Secondary datum would be the feature which has the second most influence on the resulting fit or alignment of the hole feature. The tertiary, would have the least effect of the installation and alignment of the hole feature. There are other philosophies based on installation order of precedence, as well, as piece part manufacturing sequence, which work well, particularity when most the part or components features are manufactured within the same setup.
|
| Post Reply | Recommend | Alert | Where am I? Original Top of thread | | | |
| Re: GD&T Position Tolerance WRT Datum Order | |||
| Re: Re: GD&T Position Tolerance WRT Datum Order -- Kelly_Bramble | Post Reply | Top of thread | Forum |
|
Posted by: gravynorth ® 06/08/2005, 13:46:59 Author Profile Mail author Edit |
Thanks for the quick reply, Kelly!! |
| Post Reply | Recommend | Alert | Where am I? Original Top of thread |
Powered by Engineers Edge
© Copyright 2000 - 2024, by Engineers Edge, LLC All rights reserved. Disclaimer