Filleting Problems

Post here for help on using FreeCAD's graphical user interface (GUI).
Forum rules
and Helpful information
IMPORTANT: Please click here and read this first, before asking for help

Also, be nice to others! Read the FreeCAD code of conduct!
drmacro
Veteran
Posts: 8865
Joined: Sun Mar 02, 2014 4:35 pm

Re: Filleting Problems

Post by drmacro »

RussG wrote: Fri Aug 12, 2022 7:01 pm
Shalmeneser wrote: Fri Aug 12, 2022 6:31 pm Before refine (when the adjacent coplanar faces are fused), the corner counts 5 edges.
After refine, a useless seam dissapears ant the filet can work.
By any chance are you (or anybody else for that matter) aware of a discussion anywhere on using "refine". A quick search on YouTube turned up a few things which I will look at, but if there is a written disillusion somewhere I'd be interested to see it. Thanks.
With experience it becomes easier to decide whether or not it may help or hinder. (And, yes, sometimes it can cause issues later in the model or break more than it fixes...)

Since it is situation dependent it is difficult to write rules for it.

My rule of thumb is, if it might get rid of a seam line that a next operation would cross, I try it.

And, if there is a seam that would be part of a fillet or chamfer, try it.

If the seam line/s happen to create a coplaner situation, try it.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
chrisb
Veteran
Posts: 53919
Joined: Tue Mar 17, 2015 9:14 am

Re: Filleting Problems

Post by chrisb »

to add to drmacros advice: don't refine helixes. I.e. if you need both, a helix and refinement for successful filleting, then you should rearrange the features so that you can make the fillets before the helix.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
user1234
Veteran
Posts: 3328
Joined: Mon Jul 11, 2016 5:08 pm

Re: Filleting Problems

Post by user1234 »

RussG wrote: Fri Aug 12, 2022 6:15 pm How is one supposed to know when to refine? Is it something to do regularly or just one unexpected problem occur?
Even when you use an other CAD, when connections like that are not refined, they mostly make issues while filleting or chamfering. I have set refine true as default in my settings. But as other mentions, in can make (rarely) issues. In my subjective opinion, refine true as default is better then refine is false. But as i wrote, very subjective and can be changed in the settings.

But why is there a function like that? Why it is not all refined per default? Reason: sometimes you need unrefined shapes. For example when you have to calculate a model with FEM and you only have a force on a specific area, which have per se no boundaries (or there are not near), then you need a unrefined model. Same thing on compsolids, that is the same, except there are solid in solids unrefined.

2022-08-13_17-13.png
2022-08-13_17-13.png (85.66 KiB) Viewed 402 times

Greetings
user1234
chrisb
Veteran
Posts: 53919
Joined: Tue Mar 17, 2015 9:14 am

Re: Filleting Problems

Post by chrisb »

user1234 wrote: Sat Aug 13, 2022 3:15 pm But why is there a function like that?
There is another good reason, at least for OCC based FreeCAD: The cases where refine is needed but not present need little experience: In most cases you see a vertex where 4 edges meet or something similar and this leads directly to a problem.

The cases where refine is present but should be avoided are much more tricky, because nothing can be seen and the model just fails, often not directly after the critical refine but several steps later.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
RussG
Posts: 124
Joined: Wed Apr 27, 2022 11:27 pm

Re: Filleting Problems

Post by RussG »

chrisb wrote: Sat Aug 13, 2022 11:51 pm
user1234 wrote: Sat Aug 13, 2022 3:15 pm But why is there a function like that?
There is another good reason, at least for OCC based FreeCAD: The cases where refine is needed but not present need little experience: In most cases you see a vertex where 4 edges meet or something similar and this leads directly to a problem.

The cases where refine is present but should be avoided are much more tricky, because nothing can be seen and the model just fails, often not directly after the critical refine but several steps later.
Thanks for the tips.

It sure sounds like using refine is an acquired skill or perhaps something akin to an art developed through practice over a long period of time.
user1234
Veteran
Posts: 3328
Joined: Mon Jul 11, 2016 5:08 pm

Re: Filleting Problems

Post by user1234 »

chrisb wrote: Sat Aug 13, 2022 11:51 pm There is another good reason, at least for OCC based FreeCAD: The cases where refine is needed but not present need little experience: In most cases you see a vertex where 4 edges meet or something similar and this leads directly to a problem.
Since i refine it per default, i rarely see some issues like that. Therefore i have extreme seldom issues with refine anyway.


Greetings
user1234
Post Reply