[SOLVED] Why's a Cone Solid not a Solid?

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!
User avatar
KDM
Posts: 147
Joined: Sun Feb 20, 2022 9:30 am

[SOLVED] Why's a Cone Solid not a Solid?

Post by KDM »

In the enclosed file, when I try to subtract my "Drill" from my "solid" I'm told that the use of non-solids for Boolean operations will cause me headaches. Sure enough, the slicer for my 3D printer then complains that my total object is not a closed solid.

I've narrowed it down to the cone. ("Locator" in my model.)

It looks pretty damned solid to me and when I try to convert it to a solid, nothing evident happens.

Can you please help me understand why a cone solid isn't solid?

Thanks!
Pug 207 Overhead Handle Blank.FCStd
(60.75 KiB) Downloaded 12 times
Last edited by KDM on Sun Oct 09, 2022 10:30 am, edited 1 time in total.
User avatar
Shalmeneser
Veteran
Posts: 9475
Joined: Wed Dec 23, 2020 12:04 am
Location: Fr

Re: Why's a Cone Solid not a Solid?

Post by Shalmeneser »

Locator cone is a problem.
Modifying the order of fuse / cut can solve the problem.
User avatar
KDM
Posts: 147
Joined: Sun Feb 20, 2022 9:30 am

Re: Why's a Cone Solid not a Solid?

Post by KDM »

Yes, The question is all about the cone. I narrowed it to that component.
Are you saying "cone" is a known problem?
I've no idea what a fuse is, but it somehow fixed itself when I added some fillets.
(Enc.)
Attachments
Pug 207 Overhead Handle Blank.FCStd
(88.68 KiB) Downloaded 6 times
User avatar
Shalmeneser
Veteran
Posts: 9475
Joined: Wed Dec 23, 2020 12:04 am
Location: Fr

Re: Why's a Cone Solid not a Solid?

Post by Shalmeneser »

* Fuse = union
* Don't know if cone feature can cause problem
* cone here is a problem
domad
Veteran
Posts: 2053
Joined: Mon Jun 22, 2020 12:16 pm

Re: Why's a Cone Solid not a Solid?

Post by domad »

KDM wrote: Fri Jul 01, 2022 3:26 pm .......
Hi KDM, greetings to the community!
Try setting the major radius of the cone (Locator) to 2,999 everything should work again.
Locator (cone) -> "Properties" panel -> "Data" tab -> "Radius1" parameter -> 2,999.
User avatar
KDM
Posts: 147
Joined: Sun Feb 20, 2022 9:30 am

Re: Why's a Cone Solid not a Solid?

Post by KDM »

It seems that just about any minor change I make to the geometry fixes the problem.

Now, how about helping me "understand!?!?"

Is it just some weirdness we need to tolerate?

Thanks, all.
drmacro
Veteran
Posts: 8867
Joined: Sun Mar 02, 2014 4:35 pm

Re: Why's a Cone Solid not a Solid?

Post by drmacro »

KDM wrote: Fri Jul 01, 2022 4:20 pm It seems that just about any minor change I make to the geometry fixes the problem.

Now, how about helping me "understand!?!?"

Is it just some weirdness we need to tolerate?

Thanks, all.
The modelling kernel (OpenCASCADE) has issues that are referred to as "coplaner" issues.

Basically, because two things that are specified, for example, the same diameter cause issues because of floating point representation.

So, when they are used in, for example, a Boolean operation, the two identical planes in the same 3D space don't resolve to a single value. In many things like this, fillets, etc. will work if you force the overlap as you've seen.

I guess the answer is yes, we need to tolerate it, since FreeCAD has little, if any, influence on what OpenCASCADE fixes or improves.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
User avatar
KDM
Posts: 147
Joined: Sun Feb 20, 2022 9:30 am

Re: Why's a Cone Solid not a Solid?

Post by KDM »

So, I historically "force the overlap" (experience in other modelling packages) in order to make sure the bodies conjoin properly. Is this my problem? I've put the con larger radius end INSIDE the supporting block. Should I have set it on top?
domad
Veteran
Posts: 2053
Joined: Mon Jun 22, 2020 12:16 pm

Re: Why's a Cone Solid not a Solid?

Post by domad »

KDM wrote: Fri Jul 01, 2022 10:13 pm ......
Hello KDM, greetings to the Community!
He explained exactly how the @drmacro problem originates, practically OpenCASCADE must understand with certainty (!) That the base of the cone (Locator) intersects or does not intersect the lateral surface of the "parallelepiped" (Locator Sq), if the position is ambiguous (as in your case) then it produces an error, therefore we must force to make it "understand" by increasing or decreasing (by some infinitesimal), the one that suits us best, the radius of the cone (Locator) or the width dimension of the parallelepiped (Locator Sq).
Attachments
ambiguous.png
ambiguous.png (141.43 KiB) Viewed 426 times
User avatar
KDM
Posts: 147
Joined: Sun Feb 20, 2022 9:30 am

Re: Why's a Cone Solid not a Solid?

Post by KDM »

domad wrote: Sat Jul 02, 2022 6:21 am
Aaahhh... I get it. It's a library we employ but didn't write.

Stupid question: what if the base of the cone purposely had a base 1mm greater in radius than the half diameter of the parallelepiped? Do I have teh same problem that the intersection is ambiguous?

(I wanted to try it but now that I've chamfered the edges, I can't recreate the problem. Even if I remove the chamfer!!)

In case there was any doubt, I'm not grouchy about it... This is still a million times better than any other CAD software. Just the right level of floundering!
Post Reply