Datum target areas or points ?
Datum target areas or points ?
(OP)
Attached print is a forged part around 11 inches long, there is a 3° draft angle all around the contour, for an irregular forged surfaces datum reference frame should be established by datum targets which could be points, lines or areas, the print note specified "all datum target areas are Ø.093".(The original print specified with a X-shaped symbol as datum target area)
For datum A, it's easy to understand a datum target areas A1, A2 and A3 could be assigned to on the flat surface, my questions are :
1. There is a 3° draft angle on the side wall datum B, shall we made a 3° end face on the B1 and B2 target pins ( Ø.093) to match with the side wall ? Why not to choose datum target points here ?
2. Besides 3° draft angle on Datum C, it's a curved contour on this end, shall we made a 3° and curved end face on the C1 target pin ( Ø.093) to match with the part contour as well ? Can we use datum target points here ?
Any comment or help is appreciated
SeasonLee





RE: Datum target areas or points ?
Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Datum target areas or points ?
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Datum target areas or points ?
Can your make your pin faces spherical?
A spherical face can contact the draft angle at the precise point indicated.
RE: Datum target areas or points ?
Yes, JGH. This is what I wanted, a datum target point means a spherical-tipped pin.
SeasonLee
RE: Datum target areas or points ?
But lets say on that surface you had a draft angle of 3 degrees basic. That of course would change everything. Your datum feature simulator would be inclined 3 degrees to the datum reference frame plane perpendicular to the primary datum plane.
Remembering that the targets simply partition the datum feature, if you want the pins inclined, call the draft angle on that side basic. Of course, then you have to control it with a profile or angular tolerance of some sort. But that's another problem. Maybe a small one.