DATUM TARGET PLACEMENT
DATUM TARGET PLACEMENT
(OP)
ASME Y14.5-2009. I am checking a small casting, product design drawing. The part is about 6 x .75 x 2.5 inches. The tooling/manufacturing engineer wants datum A's three target areas to be on 3 different surfaces of the casted part. Datum B's two targets are on one surface and C is perpendicular to DATUM B. There are GD&T FCF referencing holes relative to A,B,&C.
The design engineer shows DATUM A as a vertical plane in the side view. There are offset BSC dims locating the other two datum A target areas. In all the views, DATUM A plane shows perpendicular to DATUM B AND C.
My query is since DATUM A's target areas create an angled plane in relation to B & C, how does that work pictorially? Do I show it angled or perpendicular like the engineer has on his product design drawing?
Thanks for your help, I'm hoping to receive.
The design engineer shows DATUM A as a vertical plane in the side view. There are offset BSC dims locating the other two datum A target areas. In all the views, DATUM A plane shows perpendicular to DATUM B AND C.
My query is since DATUM A's target areas create an angled plane in relation to B & C, how does that work pictorially? Do I show it angled or perpendicular like the engineer has on his product design drawing?
Thanks for your help, I'm hoping to receive.





RE: DATUM TARGET PLACEMENT
Frank
RE: DATUM TARGET PLACEMENT
RE: DATUM TARGET PLACEMENT
“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV
RE: DATUM TARGET PLACEMENT
RE: DATUM TARGET PLACEMENT
No -- since you state that there are basic dimensions showing an offset between the different A targets, then the true datum A will not be angled.
If you're able to include a sketch, that will help. But since you have the 2009 standard, look at Figure 4-47. Notice that the targets for datum A appear to create an angled plane if you connect them all. But that's not the real datum; the true datum A is a plane that is horizontal. This is because of the 20 mm basic dimension showing their offset. (Without that basic dim, datum A would be angled.)
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: DATUM TARGET PLACEMENT
Also, thanks to all of you for the help.