It makes sense if you think of parametric modelling as providing an
easy way to fiddle with the parameters (arguments) to the equations
you've set up to establish the relationships between the various
features of your model. In practice, most of the math is done in the
background in response to relationships that are graphically
represented by cute little icons on your monitor.
BTW, Parametric Technology produces ProEngineer, another modeller. The
ProE and SW articles on Wikipedia have descriptions of the design
methods that are common to most parametric modellers.
The basic idea is that internally, if an old-style nonparametric CAD
program calculates some quantity (say, the length of something-or-other),
it then stores the resulting quantity. A parametric CAD program stores
the recipe for performing the calculation.
So instead of a variable in your design being stored as, say "the length
is 100mm", it's stored as "the length is equal to the length of bolt A
minus the width of nut B". This means that if you resize bolt A, any
part of the design that was calculated from its dimensions changes
appropriately, rather than you having to go back and change it yourself.
In both programs, there is a feature to calculate the length (100mm) from
the length of bolt A, and the width of nut B; the difference is that the
parametric program remembers how it calculated it.
(My understanding of this comes largely from talking to someone who had
worked as a programmer at Parametric Technology, which was the company
that basically invented the concept.)
Hide quoted text -
I agree with Norman in a quite academic sense. The way I differentiate
the two practically is the overall focus of the user.
So.. What does the OP do?
In my experience, parametric for assemblies, drafting for parts. (This
potentially changes for complicated parts with 3D features, however.
Not something every user has to worry about though)
I learned on AutoCAD in highschool. Still applies today. Making
beautiful engineering drawings of single parts that a tradesperson can
build is best done in CAD. Total control over every portion of every
line. Just the way it ought to be.
Building assemblies (tooling, machinery, complex products, etc.) is
far and away superior in parametric modeling. Assemblies are a total
gong show in drafting software. Too cumbersome to make, too cumbersome
to change. Not worth the time. Would rather widdle them out of sticks.
I bought Alibre because I am a tool maker and I need to design
assemblies (dies and machinery) and I need to see collisions and how
things are going to go together. Ultimately I do have to produce
working drawings, but mostly just for myself which is acceptable with
Alibre. I can make pretty good working drawings for outside
contractors with Alibre, but drafting software would be superior if it
was my main focus.
Just my $0.02 worth.
Regards,
Robin
I agree with Norman in a quite academic sense. The way I differentiate
the two practically is the overall focus of the user.
So.. What does the OP do?
In my experience, parametric for assemblies, drafting for parts. (This
potentially changes for complicated parts with 3D features, however.
Not something every user has to worry about though)
I learned on AutoCAD in highschool. Still applies today. Making
beautiful engineering drawings of single parts that a tradesperson can
build is best done in CAD. Total control over every portion of every
line. Just the way it ought to be.
Building assemblies (tooling, machinery, complex products, etc.) is
far and away superior in parametric modeling. Assemblies are a total
gong show in drafting software. Too cumbersome to make, too cumbersome
to change. Not worth the time. Would rather widdle them out of sticks.
I bought Alibre because I am a tool maker and I need to design
assemblies (dies and machinery) and I need to see collisions and how
things are going to go together. Ultimately I do have to produce
working drawings, but mostly just for myself which is acceptable with
Alibre. I can make pretty good working drawings for outside
contractors with Alibre, but drafting software would be superior if it
was my main focus.
Just my $0.02 worth.
=================================================
Inneresting and cogent distillation.
But, if Alibre can do assemblies, why wouldn't it be able to do a bang-up
job on drafting-type drawings?
Too much drama, given its horsepower, for simpler tasks?
Or does it really just produce merely "acceptable" working drawings? Why?
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