For us, drawing and model are always identical.
For "real" changes (e.g--change a dim) we use whole number revisions (e.g.--
For "cosmetic" changes (e.g.-add a missing dim to a print) we use decimal
For a while, we tried using mixed Revs (e.g--dwg @ 2.1, part at 2) but found
that it generated enough issues that we abandoned it. The minor extra
paperwork to change them both is easily worth the aggravation and confusion
it's saved us.
In our case, the revision of the sheet is the same as the part, because when
you change the part, the sheet must be change and also the sheet indicates
the revision of the part. So for all of these, we decided that sheet and
part carry the same revision.
I've seen people do it both ways, and there are good reasons for doing it
either way. When I implemented a PDM system, I opted for separate revs for
model and drawing. The model will change many times before a drawing is
made, and changes to the drawing may be independent of the model. We
really didn't use the model for anything other than making the drawing and
doing some FEA. We tracked the model rev, but didn't link it to the
People who do rapid prototypes or CNC from the model may feel the need for
the drawing and the part to always have the same rev. The only real
problem with this is that most PDM systems see the model and the drawing as
being two separate (but related) documents, and each document has its own
One way around that might be to list the model rev in the drawing title
block so from the drawing you will know that Rev B of the drawing relates
to Rev E of the model. You might even give the model a different sort of
rev designation, like numeric, to make sure that the drawing and model are
Remember also that some PDM systems (like PDMWorks) give you the ability to
pull up referenced documents using the "as built" or "latest" revision of
We used to use Revision for the Part, and Version for the Drawing, both were
indicated on the drawing and both were populated by custom properties in the
model. This ensured when either one changed, you had to go back to the
model to make the change. This made the model the master from an
engineering point of view, even though the drawing was the master from a
manufacturing point of view.
We soon dropped this, as is proved too confusing for certain members of the
manufacturing team. Now the drawing is free to rev as often as it needs to
be, and it does not have to match the model rev.
As virtually all our parts are produced by computer controlled machines
reading the files directly in our case the model is always the master with
the drawing produced as a Check or Reference. The drawing issue number will
change whenever there is a change on the drawing, be it a 'real' change or
'cosmetic' change. The model gets a part number and issue number which is
also 'engraved' on the part to identify it. In the drawing block the model
part and issue number is shown automatically by the drawing template and
updates whenever the model 'Save As' is changed so when viewing the drawing
there is no doupt about the model part number and issue it relates to..
Hope this helps ...... Sonny
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