[Andy A.]

There are two things I always recommend to new users.

The first is to learn the sketch constraints cold. You have to know them like the back of your hand in order to produce adaptive parts that can change quickly. Inventor does your team no good if the CAD jocks can't keep up with the ever changing manufacturing. Designs are often changed in the shop, and you need to be able to update your drawings to reflect that change. This is about elventiy billion times easier if you've properly constrained your sketches and assemblies. The alternative is changing each dimension individually and it's so laborious that no one is going to do it. Then you end up with a model of the robot that isn't even remotely correct.

The other big point for me is learning to produce properly dimensioned drawings. I've seen some people who can create all sorts of geometry and make amazing looking models of complex parts and assemblies. But they can't document all that stuff with a set of prints because no one's ever showed them how. In a perfect world we would just send the part files off to a CNC shop and let the machine figure out everything else. But that's rarely the case in FIRST. We have to be able to give our machinists drawings they can work from, and that means giving them all the dimensions, tolerances that work and views that are helpful. I've always found this to be the most demanding part of my CAD work in FIRST and even more so now that I do this for a living. It doesn't matter how pretty the model is, if you can't give the factory a set of drawings and design guides that work you haven't really accomplished anything.

Does that mean we need to do all the math associated with for press fits, hole patterns and such in FIRST? Usually not. It's a complex subject and is rarely intuitive. Compared to good modeling skills it's not so important and takes much longer to master. Often we can just have a general note saying 'please get it as close as you can', and that works because most parts in FIRST are one-off's and custom fit. Still, I take the time to include tolerances where I can particularly where I know they need to be tight. The more information like this I can communicate the less pressure there is on everyone.

So, before you get into doing fancy stuff like lofts and complex sweeps spend time practicing making drawings. Show the students complete drawing sets, drawings that work and those that don't and so on.

-Andy A.