[AdamHeard]

This is actually very common, and SW/Catia have many features built in to facilitate this. I would assume Inventor has them as well.

Before any detailed component level design of a system, I ALWAYS make a sketch that fully shows the mechanism. If it's a gearbox, it shows all the gears, bolts, motors, etc... An Arm would show the whole system, and it's full range of motion. Sometimes I'll even draw multiple mechanisms on there equal, and not actually dimension the lengths, but dimension the desired end results. By geometry the lengths required for arm A and wrist B, etc. etc. will be solved automatically. This is GREAT for uneven 4 bars or pneumatic rotary mechanisms, but that's off topic.

You may find that after getting good at designing systems fully in 2d, you may not even want a reflexive option, as you know understand the system and it's associated sizes, parts and dimensions better. Pretty much, immediately going to drawing parts at the 3d component level is the WORST way to design in my opinion.

Well, once this sketch is created it can be linked a number of ways depending on whatever my preference was at the time. Austin Schuh got me into sketch blocks a while back, but I've been burned a few times by them breaking after large changes (he has as well), so I've shied away from them. Sketch blocks let you put that sketch into any number of parts and use it to pull dimensions/geometry off of. They're all linked to the original sketch as well. For simpler sketches they're fine, but 300+ features (like a whole robot), and they become a pain.

What I do now, which is far less clean than sketch blocks, but doesn't blow up as often, is to use assemblies to link parts. I'll create the same base sketch as before, and you'll still have to create the net shape of each part. After that, I'll create parts within the assembly that reference the other parts, or add equations to the original part, or just add features to existing parts that are concentric (or other relation) to their mating features on other parts.

Using this method, we currently have an elevator drawn up where we set the width of the outer section, the height of the outer section, and our bearing gap. It then makes all the appropriate changes to all parts.