Ever been working on a model only to have everything, well for lack of a better term, blow-up? Components have moved to improper locations, while others have changes shape and size?
I know I have…always at the most inconvenient time. I often find complex sketches, or incompletely constrained sketches are the cause much of the trouble.
In order to prevent these issues, it is best to think simple when working with sketches. Each sketch should have only a few geometric and dimensional constraints to full define it. I have my best results when working by:
- Allowing Inventor to automatically apply constraints.
- Creating most of the lines for shape, verifying and adjust geometric constraints
- Adding dimensions after the shape is geometrically defined
- Purposely reviewing (again) the geometric constraints before finishing the sketch.
- Keeping every sketch as simple as possible
- Use Inventor’s Feature tools to pattern, fillet and radius features
Let’s consider the part shown here. It is a steam chest, used to supply high pressure steam to a steam-cylinder, and guide the control valve. The Inventor part files are found here – Steam Chest.
It is a sample of a part that ended up way more complicated than it needed. When I modeled it, I was working from a 2D drawing for the part. I started by modeling exactly what I saw on the source drawing, one feature and dimensions at a time. The result is a model that while accurate, it is horribly difficult to work with.
- The dimensions are a mess
- The sketches are hard to edit
- Very unpredictable results if edited
Since first modeling this part, I have recreated it to take advantage of this Inventor Best Practice making it easier to work with.
- Each sketch is a simply shape
- Patterned features build the part
- Editing is much faster and more predictable.
I’ve cheated a bit and not completed the Best Practice part, but it still shows the benefits of keeping things simple and clear, especially when combine with some of other of my other Inventor Best Practice recommendations.