Fillet fails examples 2023-03 - hammering collection

[skysurfer]

This fillets are really annoying.would be nice to have a solution form the software without the need of manual workaround.
Not to be redundant but this is easily solved in parametric software.

[lander (CAD CAM CNC)]

@Tom_P

maybe _filletEdge should check for coplanar Faces ?

This is a great example. It’s one of the biggest reasons Rhino fails imo. Rhino just doesn’t realize it can delete faces or move the edge or something lol – or add coplanar face…etc.

I’ll be relentlessly reflecting on this over time, and any others I can think of.

@Tom_P

This is a great example too, one that’s been on my mind. I’ll share similar stuff in the future.

[lander (CAD CAM CNC)]

@Tom_P

somehow rhino does get into struggle, if a surface is completely removed by
_filletEdge

fillet_surface_not_earsed.3dm (3.0 MB)

I played with this file a little bit, and I’m really surprised how bad Rhino is at the fullnose radius

wow

…
I was messing with file tolerance and almost got it to work:

Yeah, I can’t get it to work. I had no idea it was this bad lol

[davidcockey]

@lander

I was messing with file tolerance and almost got it to work:

Changing tolerances in the middle of modeling is a great way to cause problems with edges not matching and similar.

An absolute tolerance of 2.0 is an almost certain method of causing assorted problems, including with edges.

Absolute Tolerance - Set and leave alone, and other good practices

“Absolute tolerance” is the amount of deviation from the “exact” solution Rhino will allow when a curve, edge or surface resulting from various operations cannot be modeled exactly using NURBS. For example the curve resulting from intersecting two non-planar surfaces will ususally not be exacty a NURBS curve. Rhino can create a NURBS curve which approximates the exact curve within almost any desired level of accuracy but as the maximum deviation from the exact curve is reduced the number of con…

Understanding Tolerances [McNeel Wiki]

[lander (CAD CAM CNC)]

@davidcockey

Changing tolerances in the middle of modeling is a great way to cause problems with edges not matching and similar.

I’m thoroughly aware of that probability.

But when Rhino fails to fillet even the most simple task, I think it warrants a little adjustment to tolerance – even if it’s “in the middle of modeling”.

I also tried building the model from scratch after tolerance instances changes.

@davidcockey

An absolute tolerance of 2.0 is an almost certain method of causing assorted problems, including with edges.

I’m thoroughly aware of that. I’ve been around the barbeque since 2004.

@davidcockey Why does Rhino fail to fillet the most simple task regardless of tolerance?

Notice how the changes to the tolerance almost got it to work? – probably nothing tho right?

@davidcockey

“Absolute tolerance” is the amount of deviation from the “exact” solution Rhino will allow when a curve, edge or surface resulting from various operations cannot be modeled exactly

That’s why I was changing it

I thought, “oh maybe it’s having a hard time doing it ‘exactly’”. And it almost worked I thought.

@davidcockey

Set the absolute tolerance at the beginning of a project, and then leave it alone.

lol. I’m good. I’ll change it when I want.

@davidcockey

Varying tolerance while modeling will typically lead to some operations failing.

Or can lead to some operations succeeding – like joining edges to become ‘closed’.

Tolerance is relative. If I get a file from a client and the model has errors under a tolerance of 0.0001", but it will close @ 0.0005", I’ll be changing the tolerance mid-build if I want to move forward with said relativity.

@davidcockey

Absolute tolerance should not be made larger so that an operation works, and then reset to the original smaller value.

Probably true, unless the operation isn’t working cause there isn’t enough tolerance, then the user can decide to do so if they want. That’s probably why the option is there.

I made a tool pallet specifically for doing so in V5, maybe I should share it with you ta ruffle some feathers

I should rename it ‘mid-build tolerance toggle’:

I literally made that pallet in like 2011 or so, for a client as per their request.

They’ve been asking me to do it again recently – they’re not very good about managing their pallets.

So, it’s been on my mind – I’ll probably make a new version for V7 soon.

If Rhino fails to successfully fillet the most basic full-nose-radius geometry regardless of a dozen different tolerance combinations, then the problem isn’t the ‘tolerance changes mid build’.

‘Tolerance’ should be a ‘threshold’ that Rhino can use to deviate various transformations.

I was merely changing tolerance as an experiment to see if it was related.

Now I know, Rhino probably isn’t failing due to tolerance strictness. It’s failing due to something else.

[Tom_P]

180 degree edge

@Tom_P

the edge in question is a 180 or 360-degree edge.

surfaces near the edge (additional…)

see also further up

@Tom_P

if a surface is touched by the fillet, but is not part of the edge
_filletEdge fails.

the red fillet is not found by _filletEdge it has to be done manually by _filletSrf

it would be possible to detect:
if the rolling ball touches additional edges - they might have to be analysed as well.
latest if filleting / trimming the edge fails, it should be possible to analyse the offsets of the surfaces.
all corresponding surface offsets that intersect are affected by the fillet

@pascal

Yep - this is behind probably a large majority of failure cases.
-Pascal

[Tom_P]

here is another nice example, where _filletEdge fails

Model-Mania_-In-person-2023.pdf

done manual with _filletSrf…
(and a few tricks to use _filletEdge for most of the stuff…)

clamp_2023.3dm (5.1 MB)

… it was the original Idea of this topic just to collect examples…

[Tom_P]

Another nice example of filletEdge fails

Filleting issue

I’ve just come across a great example of unexpected solid fillet edge failure. In this example, the fillet edge across two edges fails, but works when broken up into a few more steps… This shows that the geometry clearly allows for an outcome that works, and one would hope it would happen in one go…(!) [Fillet issue4.3dm] Fillet issue4.3dm (486.6 KB)

[lander (CAD CAM CNC)]

@Tom_P

… it was the original Idea of this topic just to collect examples…

I think that’s a good thing, but at some point these issues should be distilled down to the principle causalities that lead to these failures.

These examples seem to becoming redundant.

I’m pretty sure there’s a list somewhere that explicates what’s causing every single failure.

The developers probably have a list by now, I’d imagine. Right?

Probably one of the main reasons ‘filletsrf’ doesn’t fail when ‘filletedge’ does, is due to lack of trimming requisites.

‘filletedge’ fails alot due to adjacent edges to the edges being filleted.

(You could probably split an edge, within a ‘filletedge’, with an adjacent edge, upto any successful ‘filletedge’, and that ‘filletedge’ would fail.)

So, with that well-known causality, what code is missing in Rhino that would overcome said causality?

Maybe there’s a pattern throughout Rhino with other commands. This issue sounds similar:

@jim

So when Rhino’s Intersect command is generating a set of points that will be used to create an output curve and the algorithm arrives at an area where both surfaces are tangent (i.e. have the same surface normal direction) it should not dive for the nearest boundary. That strategy may be the easy way out for the developer, but is disastrous for the user. What the algorithm should do is pick that next point that is closest to being in a straight line with the last 2 points the algorithm generated.

The same thing applies for the pointy fillets. The problem with pointy fillets just like the intersect command is that when it gets close enough to an edge it gets sucked to that edge instead of proceeding in the direction closest to which it is currently going. If any edge is going to be involved in the algorithm then it should only be at the point where the edge of both surfaces are closest.

[Tom_P]

@menno
even if there is already a lot of work above…
I will keep collecting:

Variable fillet on Polysurface

• my guess, this example also shows some weakness of the current algorithms:

with a tricky setup (left, splitAtTangent = No, mergeSrf) FilletEdge can do the variable fillet, with a standard polysurface (right) not:

fillet edge setting:

result:

fillet_fail_Stecker_00.3dm (3.6 MB)

Background … Detail of this power-plug

kind regards -tom

[menno (Menno Deij - van Rijswijk)]

Thanks. I have added this to the list of existing fillet edge issues.
Please understand that this will take time to fix, where hopefully we can do something for v9.

[Tom_P]

@menno

will take time to fix

… take the time needed… great to know somebody is working on it.

[Tom_P]

@ftzuk

I use Rhino mostly for grasshopper but had a recent project that was to generate marketing images so I decided to model everything in Rhino. Is there a reason why fillets are so bad in Rhino? In every other cad package I use a fillet can be used like a design tool to drive geometry, but in Rhino anything beyond the most basic of fillets seems to fail most of the time.

We’re already at V.8 of this software so I’m assuming there’s a reason fillets behave so differently in Rhino vs. other cad software?

So here’s two basic pieces of geometry:
test-block.stp (39.9 KB)

In Creo applying a R20 fillet to the cylinder and R10 to the other object:

In Fusion360 applying a R20 fillet to the cylinder and R10 to the other object:

In Rhino applying a R20 fillet to the cylinder and R10 to the other object:

see also post above

[lander (CAD CAM CNC)]

don’t worry Rhino still like ya

Hope we get Rhino to fillet better someday.

That looks like a good thread, imma check it out.

[Tom_P]

fillet fails at Pole of _railrevolve

see this file / topic:

@ld.power

anyone could please take a look that would be greatly appreciated!

help file.3dm (236.3 KB)

Many thanks

@Tom_P

here you go.

@Tom_P

help_file-2_R1_tp.3dm (3.5 MB)

workaround:

[Tom_P]

@menno
hope you have seen this topic - related to Surface Filleting across Tangent Faces

and @Gijs
would love to see above cases to be in the collection here as well:

@Gijs

@Rhino_Bulgaria

a short video overview with a few examples

looking forward to see those very welcome improvements - thanks - cheers - tom

[markintheozarks]

Hi Tom , isn’t some of this is the way things are built as to why they don’t work? I don’t claim to know the right way, but have seen enough examples like singularities and three sided surfaces are not a good way for things to work.
There are always people here at the forum that bring Rhino a little further in development. It’s guys like you that are bringing it for sure.—-Mark

[Gijs (Gijs de Zwart)]

@Tom_P

would love to see above cases to be in the collection here as wel

what do you mean? That all samples from this thread get added to the file with samples that Jim provided?

[Tom_P]

@Tom_P

in the collection

ok i thought the file in the video was your collection / your test file, did not get if from the context that it s jim’s file. sorry for not following the topic with all infos..

kind regards - tom

[Rhino_Bulgaria (Bobi)]

Here is another case where the fillets failed.

Fillet fails in Plasticity, found a solution in Rhino.3dm (738.2 KB)

Just some fun with fillets in Rhino

At the 1:18 minute of the video I had to use ! _FilletSrf, because the ! _FilletEdge failed to do a 40 mm fillet. The latter worked only on fillets with a radius of less than 35 mm, because the horizontal fillets made prior that step were also 35 mm. Most likely the variable conical fillet on the right side has caused some conflicts due to its radius being gradually smaller.

Also, at the 2:08 minute of the video even the ! _FilletSrf failed, so I was forced to use the trick with extending both ends and then manually move the end control points to the desired location via the ! _SetPt command.

Hopefully Rhino 9 will perform better in these two situations, so that the users could do the job faster instead of finding workarounds…