Datum selection based on manufacturing or upper level assembly
Datum selection based on manufacturing or upper level assembly
(OP)
Just wanted an opinion on this one...
This is my thought on the subject.
Plate with a hole in the center.
The center hole is created by holding the bottom surface and 2 sides.
The plate is assembled by placing a bolt to the hole and clamping against the large bottom surface
I would do the following:
Bottom of the plate has primary
The hole as secondary
Possibly one edge has tertiary (if needed)
Some people follow the manufacturing method.
Bottom as primary
Side as secondary
Side as tertiary
Any thoughts on this??
This is my thought on the subject.
Plate with a hole in the center.
The center hole is created by holding the bottom surface and 2 sides.
The plate is assembled by placing a bolt to the hole and clamping against the large bottom surface
I would do the following:
Bottom of the plate has primary
The hole as secondary
Possibly one edge has tertiary (if needed)
Some people follow the manufacturing method.
Bottom as primary
Side as secondary
Side as tertiary
Any thoughts on this??





RE: Datum selection based on manufacturing or upper level assembly
We have cassettes that are located by a pin through a hole. On the drawings of the cassettes we use the hole as the secondary datum if I recall correctly.
Function/Inspection of the part is more important in the dimensioning scheme than manufacture.
You could perhaps make the face and sides Datums A, B & C then make the hole datum D and relate other features to it. Depends on the function/design of the specific part though.
RE: Datum selection based on manufacturing or upper level assembly
Not in an attempt to mimic the manufacturing method.
RE: Datum selection based on manufacturing or upper level assembly
Hierarchy in dimensioning is:
Function
Inspection
Manufacture
Of course as there's no point putting a requirement you can't inspect or otherwise verify it almost ranks equal to Function.
RE: Datum selection based on manufacturing or upper level assembly
Manufacturing must somehow follow your datum set and not change it.
Dave D.
www.qmsi.ca
RE: Datum selection based on manufacturing or upper level assembly
Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 10-27-06)
RE: Datum selection based on manufacturing or upper level assembly
Dave D.
www.qmsi.ca
RE: Datum selection based on manufacturing or upper level assembly
But you need to look at how the part is assembled in relation to a mating part ... not to a machine.
It is all I was trying to say.
Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 10-27-06)
RE: Datum selection based on manufacturing or upper level assembly
What is it that you are looking for thoughts on?