topic Extrude (to cut) ends up extruding non-selected surrounding area instead in Fusion Design, Validate & Document Forum

Extrude (to cut) ends up extruding non-selected surrounding area instead

david.antliff — Fri, 06 Jul 2018 02:17:35 GMT

I have a sketch I've put together and there are two "centre" rectangles that I want to cut from the design. I've done it with one as I've done every other extrude, ever - simply enter extrude mode, select the rectange, then drag to cut through the body. No problem:

However the second rectangle is behaving very strangely. In the sketch, it's the "mirror" of the other one (in fact it was the original not the mirror image). When I select it to extrude, everything seems normal:

I drag down to select a cut depth:

Then I click OK and this happens!

It's as if the selected area suddenly leaked out of that rectangle into the quadrant area. Why did it do that? Why does it do that for this rectangle but not the other one, when they are mirrors of each other? The design is highly symmetrical, so I'm puzzled.

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

sanjay_jayabal — Fri, 06 Jul 2018 02:27:57 GMT

If you can share your design, it would be helpful to see what the problem might be. If you don't feel comfortable sharing the design here, please send it to me at sanjay.jayabal@autodesk.com.

To share a link to your design, right click on your design in the data panel and choose "Share Public Link". Alternately, you can do the same from the File Menu > Share.

best regards,

Sanjay Jayabal.

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

davebYYPCU — Fri, 06 Jul 2018 02:29:34 GMT

You will need to attach the file, for anything better than - that shouldn't happen.

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

david.antliff — Fri, 06 Jul 2018 02:30:27 GMT

Happy to share: https://a360.co/2KJZUw1 version 7 (currently latest).

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

sanjay_jayabal — Fri, 06 Jul 2018 05:59:56 GMT

Looks like you have a sliver segment (very small arc) that is tangent to the top edge of the rectangle (the one that has the issue you described). The sketch has several discontinuous segments with not all the segments geometrically constrained. In general, I would not recommend working with these types of sketches as it can lead to several problems. You have a couple of options,

1. Ideally, it would be good to take the time to clean up your sketch so that you don't have several of these broken segments that appear to be geometrically correct but aren't. I would also recommend adding appropriate geometric constraints. Do all this if you intend to leverage this sketch many times and/or if it is a key feature in developing downstream features.

2. If you want a quick and dirty fix just to get this specific cut working, click on the small sliver arc and drag each of its end point on to the big arcs on the left and right side. Alternately, delete the tangent constraint you have between the sliver arc and the top edge of the rectangle, instead add the tangent constraint between one of the bigger arcs (left or right) and the top edge of the rectangle.

I hope this helps.

best regards,

Sanjay Jayabal.

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

david.antliff — Fri, 06 Jul 2018 06:39:18 GMT

Thank you very much for taking a look and for your advice. I will follow it.

Incidentally, I did have more constraints on this drawing in earlier versions but I deleted a lot of them because it was running so awfully slowly on my 2017 Macbook Pro. Deleting them seemed to speed things up a bit. I've watched YouTube videos of people using Fusion 360 and it looks effortless and fast for almost everyone, but for some reason it runs like treacle on my pretty modern and fast MBP. Doesn't seem to be a video problem either - rendering is fine, it's the 1-2 seconds delay between being able to trim each line that really hurts! 🙂

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

david.antliff — Fri, 06 Jul 2018 07:00:51 GMT

Ok, just for completeness, I'm following up with my changes. I realised that I'd accidentally "trimmed" some parts of that large circle (that touches the rectangle) when in fact I needed it intact in order to extrude it to create the centre of the spool, so I created a second circle "on top" of the existing split arcs for sole use of extrusion. But of course I must have misapplied a constraint against it rather than the arc beneath. I cleaned it up by removing all the arcs underneath the circle, so that only the circle remained. This seemed to resolve my issue. Thank you again for taking a look.

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

davebYYPCU — Fri, 06 Jul 2018 07:11:23 GMT

Best results on a performance basis, - we teach one sketch per feature, even if on the same plane.

Your example of a mirror sketch profile, would be more efficient to extrude cut one, and mirror the cut feature. etc.

Same for model body patterns, over sketch patterns, you will see big performance drag with complicated sketches....

Might help.....

Re: Extrude (to cut) ends up extruding non-selected surrounding area instead

david.antliff — Sat, 07 Jul 2018 00:12:04 GMT

Ok, mirror the features rather than mirror in the sketch - sounds sensible, I'll keep that in mind. Thank you.