Bug: Reproducible app hang when extruding from sketch inside body surface

[Anonymous]

I have a sketch on a body from which I've extruded a further section (to the top of an object). I wish to use that sketch to extrude more body but doing this causes an app crash.

To reproduce:

1. Create sketch. Draw rect. Extrude to body.
2. Draw new sketch on top of this extruded body. Draw two circles, one inside the other.
3. Extrude one profile (the outside one - you have a rectangle with a large circle cut out) to a joined body, say 3mm.
4. Now I want to extrude from top of this new body using the inner circle from the sketch. Bit difficult to see the sketch as it's embedded inside the body so I turn on the sketch and turn off the body to more easily see it.
5. Extrude two profiles up 1mm to get started - happy with that - rectangle with small circle cut out.
6. Turn on body. Extrusion now turns into a cut which is expected.
7. Select Start from object and click top of body to start from there.
8. Try to change distance to 2mm.
9. App crash.

Thanks guys!

[Anonymous]

Workaround: create a new sketch on top of surface. Project from previous sketch to new one. Extrude. No problems.

(I do have a bad habit of using one sketch for many things even when not warranted. It's not like there's a shortage of sketches).

[Phil.E]

Hi,

I'd like to try and reproduce this, but I'm having difficulty following your instructions.

Can you make a video or provide some screen shots to better explain steps 3-8?

And one more question, do you ever get a CER report dialog when this happens?

Thanks,

[Anonymous]

Yes, perhaps they're a tiny bit terse. I don't have that video thing installed so I'll try again with some screen shots. I don't get a report dialog - Fusion 360 just goes busy with one CPU fully utilised (25% in my case) and never comes back. So I have to kill the process.

[Phil.E]

Thanks, a few images should do the trick, just show the 'mid-command' state, so I can see what you are selecting and extruding at the key points. It's appreciated, I'd love to nail this bug down.

Thanks again for reporting it.

[Anonymous]

I've just started Fusion 360 and I'll start with creating a sketch on any plane. Say XZ. I'll draw a rectangle (I don't think it matters what size but this is: 25 x 17mm. Stop sketch. Select the profile and extrude to, say, 10mm:

Now I create another sketch on the top surface of this body and draw two concentric circles. Again I'm not specifying any particular size but those are 14 and 6mm:

Stop the sketch and extrude the outermost profile by, say, 3mm to create a joined body:

So far, so good. Now I want to reuse the first sketch to extrude from the top of this body. This will create a compartment (I wanted to try 3d printing a captured washer). So I go and turn the sketch back on as the extrude auto turns it off. Sometimes it's difficult to see the profiles so I also turn the body off. I'm not sure if that's related to the crash but I'm mentioning everything I did!

Select the two outermost profiles and begin the extrude:

 I go up 1mm. Don't click ok yet:

I go up 1mm. Don't click ok yet. Ok, that's what I want so I turn the body back on. Fusion 360 changes tack and says that's now a cut in the middle of an existing body rather than creating a new body. I do this all the time with joins and cuts - fusion 360 joins and cuts to bodies that are turned on at the time.

I don't want to cut. I want to extrude from the top of the existing body so I change the "Start" parameter to "from object" and click the top of the body. That's better:

Oh. Except I want a 2mm extude, not a 1mm. Let's change that..... Bang! I get as far as entering "2" and that's all she wrote:

[Phil.E]

Got it, the last couple steps were it. Well done, thank you for the clear description of the workflow. This is what I call the "big crayon" method, perfectly executed.

I'm not getting a CER, so it's hard to tell where it's crashing. That we will leave to the debuggers.

Thanks again,

[Anonymous]

Just a quick note to say that in the latest version (End of Sep 2017) I can still reproduce this - I accidently did it a few minutes ago. I must remember not to extrude from an object like that 😞

Thanks, Conor.

[Phil.E]

@Anonymous

Yes it should still be crashing.

A fix has been done, and is in testing right now. Unless we find something unexpected, or unless the update is cancelled, this should be released in about a week.

(internal reference FUS-34572)

Thanks,

[Anonymous]

Cool! Thanks Phil. I was figuring that if an extrusion from a sketch was used as a reference for another extrusion from the same sketch, Fusion 360 was going into a loop of trying to figure out references. I was going to say that if it gets stuck in a loop there it could have a maximum loop count and then fall out with an error rather than falling over.

Maybe it's just me that does that - I see most examples will just extrude from the original sketch through the existing extrusion and out to a new one. Perhaps that's better practice.

Thanks,

Conor.