Selecting all top or bottom edges of a body or component

[matejsazama]

Hello

I'm trying to write a script that prepares a model for 3d printing by chamfering the bottom edges, optionally filleting the top edges and maybe aplying offsets to the sides to get some clearance.

Now the issue is that I don't know if or how you can find a specific face or edges. Is there maybe some variable that always references the bottom side of the model or something similar?

Thank you for your help.

[BrianEkins]

There isn't a simple answer to your question.  Mostly it depends on what your models look like and what you define as "top" or "bottom".  If your models have some consistency in their shape, it's usually not too difficult to find the geometry you need.  For example, if you know you're always processing parts that can be any shape but will always be cut from a flat board, you can make assumptions that help in extracting the needed information.  However, if the input part can be anything, then it's much more difficult.  Here's a link to a paper I presented at Autodesk University a few years ago that discusses what makes up a part and the various tools you have in Fusion to examine it.

https://ekinssolutions.com/autodesk-university-2018/ 

[matejsazama]

Would knowing the starting plane help?

For example, If I know that I always start the sketch on the xy plane and extrude into the + on z axis.

[BrianEkins]

That should help you a lot but still doesn't provide enough of a description to be able to know how to be able to find the "top" or "bottom" edges.  Below are some pictures of various models I grabbed from the Fusion 360 gallery.  I know some of these are nothing like your part, but others might have some similarities.  For any of these parts, what would you say are the top edges?  It all depends on your definition of "top edges".

[matejsazama]

Okay. And is there some way to determine top or side faces from other faces?

(Let's say you select the bottom and top faces and find side faces from that)

I'm sorry if this is annoying for you, I'm just starting out with this and the only references I'm going on are fusion sample scripts and a few youtube videos.

Thank you.