Hey @EndlessStruggler !
It sounds like a lot of the issues you're having are related to understanding some of the basics of how Inventor works, and there's no harm in that. After all, we all start somewhere!
The issue with the sketch disappearing is actually by-design. In many cases, features are created based on a "1 sketch, 1 feature" basis, so Inventor hides them once they've been used so it doesn't clutter up the view really quickly.
If you look in the model browser tree though, you can click on the feature node to expand it and show the hidden sketch and make it visible again.
@JDMather mentioned that in one of his replies. He's a master with Inventor and has a ton of knowledge and great things to teach.
Some of what he said can be boiled down to the below (plus my own 2-cents) about how to model stuff.
- Be accurate, and don't leave loose ends.
- This doesn't necessarily mean lots of decimal places. It just means to constrain and dimension everything, so there's no unintended "wiggle room".
- Think about how the part will be, and use the origin features thoughtfully (you can project them into sketches and constrain to them!), perhaps so the part can be easily constrained with them in an assembly later.
- Use geometric constraints for everything that makes sense, and create dimensions for the rest. Nothing should be free to move when you're done with a sketch unless you have a specific reason to do so.
- When creating dimensions, use numbers that make sense (maybe round numbers or specific fractions), and don't be afraid to let Inventor do the math instead of you! Use manually-placed numbers where they're needed, and use the power of parametric constraints and expressions to make Inventor solve other bits.
- Be smart about being lazy.
- It's not about not doing the required work. It's about doing what is needed in the most efficient way, and using the tools that are best-suited to help you get there.
- For example, Inventor is great at creating patterns, especially for features (and has more workflows for them compared to patterns within sketches). Don't draw all that stuff manually. Do the first one, then make Inventor do the rest of the work for you!
- Inventor has a great number of tools and commands, and many of them seem like they do very similar things. Pay close attention to those ones especially and don't be afraid to hit that F1 key to learn more about them. Those minor differences are there for a reason and choosing the right one can save you a lot of time later on if you learn where each one shines. A few examples:
- Even though you can just "EXTRUDE" a circle to create a hole, there are very good reasons to use the "HOLE" feature instead. Even though it may actually take a few more clicks to do, it can set you up for huge time savings later on in the assembly and drawing phases.
- Creating a single feature (like a hole) and then creating a PATTERN of it will enable you to reference that pattern at the assembly level automatically (say, for installing bolts into the patterned holes), saving you from having to place them manually.
- In SHEET METAL parts, using the specific commands like "FACE" and "CUT" enable powerful options to work with constant-thickness parts (like cutting normal to thickness or wrapping around bends) that don't exist if you just use "extrude".
