User Manual

UnDerstanDIng ParametrIc DesIgn

game, you had to knock down all of the bottles. However, if the bottle in the center on the bottom

were nailed down, it would be impossible to win the game, and as a matter of physics, it would be

difﬁcult to knock down the bottles next to it. Having a grounded component in your assemblies,

one that is “nailed down,” will likewise keep your assemblies from falling over as you build on to

them. By default, the ﬁrst component you place into an empty assembly ﬁle will automatically be

grounded. You can unground it and ground another if need be, but you should always maintain at

least one grounded component. You can also have more than one grounded component.

ma K e yo u r mo D e l s mi m i c t h e ma n u F a c t u r i n g pr o c e s s

The simplest advice that new users can receive on the subject of assemblies is to structure them

as you would in real life. If in the design you plan to assemble several parts into a transmission

and then drop that transmission into a housing, then you should make the transmission a sub-

assembly and insert it into the upper-level housing assembly. Alternatively, a new user might

place all of the parts into one big assembly, only to later realize that subassemblies are needed

for the purpose of getting the bill of materials organized. By making your models mimic the

manufacturing process, you can also ﬁnd possible ﬂaws in your design, such as fasteners that

cannot be accessed or areas where parts may interfere with each other during assembly.

In some instances a model will be developed in the research and development (R&D)

department and then handed to the manufacturing engineering (ME) department to be built.

Although the folks in R&D may enjoy the freedom of “dreaming up” anything they can think

of, an effective R&D designer will always have one eye on what can actually be built within the

capabilities of the shop ﬂoor. Keep this in mind during the initial development cycle, and it will

prevent those downstream from having to re-create much of your work. However, if restruc-

turing the components into more or fewer subassemblies is required after the initial design,

Inventor has demote and promote tools to assist with that. These tools will be covered in the

chapters to come.

co n s t r a i n t o or i g i n ge o m e t r y

As mentioned earlier in this chapter, each part ﬁle has default origin geometry built in. You

should build parts around the origin geometry whenever possible. For instance, a transmission

has gears, bearings, seals, and so on that are all concentric with the shaft. If you model all the

parts so their x-axes will be aligned in the assembly, then you can use the x-axis of each part

Figure 1.7

The Model browser

showing the model

tree of an assembly

named Router.iam

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