Fillet mirror fail

[DRoam]

In the image above, the notch on the right-hand side was made using a rectangular cut extrusion (Notch Cut) followed by a fillet feature (Notch Fillet), which applies two inside-corner fillets (green) and two outside-corner fillets (red).

Then a mirror feature is created which includes BOTH the Notch Cut and the Notch Fillet features, across the exact midplane of the part.

For some reason, the inside-corner fillets mirror successfully, but the outside-corner fillets do not. No error or warning is generated. The preview of the notch fillet would seem to indicate that the outside-corner fillets will mirror successfully, but they don't.

I have tried both the "Identical" and "Adjust" creation methods for the Mirror.

Why are the outside fillets not being mirrored?

I've attached the part in Inventor 2017 format.

Running Inventor 2017.4.6 on Windows 10 64-bit.

[DRoam]

PS, I'm not looking for workarounds. I'm aware of many ways to get around the problem. I'd like to find out why this is happening in the first place.

[Cadmanto]

Because the fillet is associated with the selected edge.  When you mirror it, the edge becomes different and there fore fails.  

You don't want work arounds, but my suggestion would be to place the fillets inside of the sketch.  Then it will mirror fine.

https://forums.autodesk.com/t5/inventor-forum/not-all-fillets-are-get-mirrored-help/td-p/7575533

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[CCarreiras]

HI!

The reason is... every software has bugs...

I'm Trying with the most recent version, the problem still occurs.

I tried with your part, and also i started a new part... same behavior.

Send the part to support... 

[Lewis.Young]

Haven't got a solution, but i can confirm i also run into this problem all the time!

Weirdly if you mirrored the features in the other direction (-z direction) with a user workplane it works fine.

Also, if you do two mirror operations, one for the notch and then one for the fillets, this works fine...

Lewis Young
Windows 7 x64 - 32GB Ram
Intel Xeon E5-1620 v2 @ 3.70GHz
nVidia Quadro M2000 - 4GB
Inventor Professional 2017.3
Vault Basic 2017
3ds Max 2018

[DRoam]

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@Lewis.Young wrote:

Weirdly if you mirrored the features in the other direction (-z direction) with a user workplane it works fine.

Also, if you do two mirror operations, one for the notch and then one for the fillets, this works fine..

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That is interesting! So it has something to do with mirroring them both in the same operation.

From Carlos' response, it definitely sounds like this is a bug and it's not just my system, version of Inventor, or this specific part. I'll send the file to support and see what they say.

Thanks everyone for looking into it.

[CCarreiras]

Hi!

Just to update...

I tried in every direction... no success in all directions...

I guess this is a priority issue, maybe software is morriring the fillet before the cut edges exist... no edge, no fillet.

[johnsonshiue]

Hi! This is a known limitation. The main reason why the fillets in red do not get mirrored has something to do with how the fillets were created and what faces participating in the operation. The red fillets were created on the intersection edges by the Notch Cut and the Main Extrusion. The Mirror only includes the Notch Cut but not the Main Extrusion. As a result, Inventor does not know where to place the red fillets. Also, the symmetry of the part isn't a requirement to perform mirror operation. The other side may or may have have the edges to be filleted.

Many thanks!

[DRoam]

Hi Johnson, thanks for the reply!

This sounds like a pretty serious bug to me... when I mirror an extrusion and a fillet, and I don't get any errors or warnings, I'm going to assume that everything mirrored correctly. This would be very easy to miss.

And in fact, this is just a simplified version of a much more complex part that I got from my colleague, and in the full version, there were two places where fillets had been mirrored and he had not realized they didn't all get mirrored. I believe he even had some go to production that way. Which is a costly mistake. It should have been caught, yes, but a couple of 1/8" fillets on a 20-foot-long part are easy to miss.

If this is a known issue, is a fix being actively investigated or developed? If not, why?

[johnsonshiue]

Hi Derek,

Unfortunately, like I mentioned earlier, this is a limitation. If there was a straight forward solution, it would have been done. I agree that better messaging would be very helpful. But, regardless, the fillet (when participating faces are not included) still cannot be mirrored.

Many thanks!

[Lewis.Young]

Hi @johnsonshiue,

I mentioned earlier how doing two separate mirrors, one for the notch and then one for the fillets, works fine.

Would it be possible to change the mirror command so that it can identify these inevitable situations, then proceed to perform a kind of 2-step mirror, splitting up the features so that it does work?

Lewis Young
Windows 7 x64 - 32GB Ram
Intel Xeon E5-1620 v2 @ 3.70GHz
nVidia Quadro M2000 - 4GB
Inventor Professional 2017.3
Vault Basic 2017
3ds Max 2018

[mcgyvr]

This is why I never mirror fillets..

Even in the most basic situations Inventor shows its weakness in regards to that..

[Cadmanto]

To my point, put them in the sketch and everything mirrors fine.

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[DRoam]

I'm not happy with never mirroring fillets. And I'm also not happy with putting them in the sketch. This is bad practice in my opinion, for a number of reasons (extra work, extra complexity in the sketch, removes fillets from feature history, doesn't always give the same result as a true fillet, requires extra sketches for fillets non-normal to the sketch, etc.).

My workaround for the time being will be to (I guess) ALWAYS mirror fillets separately, but that's very annoying.

@johnsonshiue, ditto @Lewis.Young's question?

[mcgyvr]

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@DRoam wrote:

I'm not happy with never mirroring fillets. And I'm also not happy with putting them in the sketch. This is bad practice in my opinion, for a number of reasons (extra work, extra complexity in the sketch, removes fillets from feature history, doesn't always give the same result as a true fillet, requires extra sketches for fillets non-normal to the sketch, etc.).

My workaround for the time being will be to (I guess) ALWAYS mirror fillets separately, but that's very annoying.

@johnsonshiue, ditto @Lewis.Young's question?

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Preaching to the choir 

[johnsonshiue]

Hi Guys,

I can definitely work with the project team to see how we can improve the behavior. This particular behavior had been a target for a few releases on and off. But, we could not find a good solution unfortunately. Like I mentioned, if it was straight forward, it would have been done. There is definitely room for improvement. But, at this moment, we just don't have a good solution.

Many thanks!

[nhedler]

5 years later and many improvements, but this still seems to be a sticky issue. Considering that there's a thread describing this issue as early as 2012, is a warning message too much to ask? IMO that would be the bare minimum expectation; even if the root issue isn't resolved yet, an operation that fails should *always* notify the user of the failure.

[IgorMir]

Honestly - I don't think there is much can be done with the request. The Red Fillet is using the face which is not getting Mirrored.  If Mirror the whole solids is not an option - than the Red fillet got to be introduced on both sides after the mirror of the cut and green fillets.
Cheers,

Igor.

[nhedler]

Perhaps, when responding to a message, consider reading the message you're responding to.

Even a warning message when a feature cannot be mirrored is better than silent failures.