Cut or combine not behaving as expected

[jamie.q.white]

Cutting using combine bodies or a cylinder cut (create cylinder > cut) give me an error that I do not understand and can't seem to work around.

I sculpted a bicycle bottom bracket lug using T-splines around a reference geometry of the solid tubes (precisely dimensioned).  I converted the T-spline to a B-rep face, and thickened it 1mm "out".

To make sure the tubes would fit into the lug (there is always a bit of imprecision in the sculpting; suggestions on how to avoid this are welcome), I attempted to subtract the reference geometry (tubes) from the thickened lug model.

After I got the error for the first time I performed a second thicken operation 0.5mm "in", and combined the "out" and "in" thicked bodies to make sure I had overlap between the lug and the tube model.

Trying to use the "create cylinder" in cut mode to cut a single tube out of the lug give the same error.

I just realized I tried to perform a "join" in the screencast I made to demonstrate the problem, but the error is the same:

Embed not working ("Your post has been changed because invalid HTML was found in the message body. The invalid HTML has been removed. Please review the message and submit the message when you are satisfied."), here is the link to a screencast documenting the problem.

http://autode.sk/1FDgfbp

I'm stumped.  It seems like I should be able to trim my lug using solid bodies, either with the "create cylinder>cut" approach or just by subtracting the tubes from the lug.

Any help appreciated.

-jamie

[Phil.E]

Happy to take a look at it. I'll respond shortly.

[jamie.q.white]

Thanks Phil!  Here is the file just in case it might be helpful:

http://a360.co/1CtCpfw

[Phil.E]

Hi,

There are a couple things going on here.

First, the attempt to use Combine in your video may have failed because you used the Join option.

But also the stand alone Extrude > Cut should not fail. I really need to see the model. Most people zip the f3d file when attaching here. Alternatively you could email me the file at phil dot eichmiller at autodesk dot com.

I also want to examine the warning you get when it fails. We may need to improve the message to be more clear. So your file will help with that too.

Thanks,

[jamie.q.white]

Hi Phil,

Thanks.  Yes, I used join when I made the screencast, but the error is the same with cut.  Regardless, shouldn't "join" also work?  What if I wanted to "join" two solid bodies?

Don't my Fusion 360 files exist in the cloud? I don't see them locally.  Did the shared link not work?  I will try to share it again:

http://a360.co/1CtCpfw

it should be downloadable.  

Could you point me to instructions on how to attach zipped f3d file?  I'd be glad to but I am not sure how.

Thanks for the help!

-jamie

[Phil.E]

To be brief:

1. Yes, join should work too.

2. Yes your files are in the cloud, but until you give me permission to get them, they are private.

* If you go to the File menu and pick Export, and use .f3d file type, you can save it locally and email or attach it here.

* Assuming you gave download permission to the link, I don't know why but I cannot open it.

* You could always invite me to the project, or email the downloaded f3d to phil dot eichmiller at autodesk dot com

* Once it's downloaded locally, you should be able to attach it like a regular file to a message using the Attachments tools.

[Phil.E · Accepted solution]

I found the issue.

The dialog says, in part, that there are "coincident faces". While you made sure to get an overlap along the cylinder face, there was also a coincident face at the top of the cylinder.

This is something we know about and should fix, eventually. The problem is more complex than this simple example would indicate.

To work around it, ensure the flat faces are not coincident.

Thanks for posting and I hope this helps!

[jamie.q.white]

Hi Phil,

Thanks a lot!  Holy cow, the error message is cryptic.  How about something in plain, clear English, like "you have to extend the tool cylinder a little bit more" ?

-jamie

[Phil.E]

Agreed, but the message is shown for multiple failures. The terms used are fairly common in CADspeak, but I agree with you fully. It's just a challenge to get specific messages for fairly generic failures.

What if it showed you with a red highlight what face is having trouble? You might have gotten it on your own, do you think? (if the face I moved was colored red when the error message was up)

[jamie.q.white]

Hi Phil,

Yes, I was thinking about how the errors could be more helpful.  Highlighting the problem face red is a great idea.  I think I would have been able to figure it out with that as a cue.

Thanks again for the help. I was stumped.

-jamie