Machining and Inspection
Machining and Inspection
(OP)
Anyone with CMM experience please! Is it practical to probe a cast surface to establish Datum A. I am afraid this is throwing some numbers out of whack. I would think you would probe a truer surface and then set the part on that?





RE: Machining and Inspection
However, cast parts often use datum targets (a circular "balloon" symbol divided in half). Do those show up on your print?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
http://www.gdtseminars.com
RE: Machining and Inspection
RE: Machining and Inspection
RE: Machining and Inspection
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Machining and Inspection
Even if the Designer only placed a datum and no datum targets, you will not easily find the "high spots". If you place the part on a surface simulating datum A, it probably would rock anyway which makes measuring pretty difficult. The 94 standard defaults to targets if the set up is not stable while the 09 standards refers to another standard.
If the casting is not cylindrical, there are 3 points on a primary datum, 2 on a secondary and 1 on a tertiary. On the primary and secondary, keep the targets as far as possible from each other and never on an edge. The tertiary target is in the center of the surface. Mark on your drawing where you placed the datum targets or try to get the targets placed on the drawing.
Good luck.
Dave D.
www.qmsi.ca
RE: Machining and Inspection