Consequences of doing fillets wrong

[KB58]

I only just discovered that there's a 3D subforum here. To not clutter the forum with replicating the entire thread, it's here https://www.alibreforum.com/forum/index.php?threads/stuck-stl-export-puzzle.22757/

In short, it matters the order in which you apply fillets to an object. Unfortunately I'm apparently pretty dim, because even after knowing this, I still haven't figured out the magic handshake on doing them in the right order, and it matters.

 

[DavidJ]

Think of it more as the computer/software being 'stupid' or 'inflexible'. Humans tend to be very adaptable and can work out 'what it should look like'. Computers have to follow rigid rules - because of options like 'tangent propagate' the order of applying fillets can make a big difference to the end result. That will affect both the appearance AND how many operations are required to get that result. You can't just lump all edges into a single fillet operation and hope, the software needs more of a steer.

See Fillets (alibre.com) for starters. There are classic exercises in several 3D CAD systems relating to 3D fillet order (try searching '3d fillet order', don't worry too much about which CAD system you find examples from). Until you've seen the effect of fillet order, it's difficult to appreciate how dramatic the difference can be. Once you've seen a few examples, you'll soon get the hang of it. The issue here apply to all 3D CAD systems.

This Alibre video does touch on the importance of 'tangent propagate', which is underlies many of the choices when determining order of fillets.
Working with Part Features Reference Videos | Alibre 3D CAD

Adding a first set of fillets can allow tangent propagate to be a massive help with subsequent fillets.

 

[KB58]

Yes, I need to work with the interface more until the right way of doing it becomes ingrained. Pretty sure part of the problem is clicking on one edge at a time, and not understanding tangent propagate, but it's clearer now.