Fusion 360 simultaneously thinks two lines are parallel and not parallel ?????

[jgranata13]

Below is a screenshot from a bracket I'm working on.  As you can see, Fusion gives me an angle of 0 between the two selected edges, which I take to mean that Fusion knows they're parallel (after I took the screenshot I set the angular precision to maximum in my preferences to make sure it wasn't an extremely tiny nonzero angle, measured again, and got 0.00000000).

But then when I try and construct a work plane through those same two edges I get the following error:

I've gone through everything with a fine-toothed comb and can't figure out what's going on.  How can I troubleshoot this before I pull my hair out or throw my computer at the wall?

[jhackney1972]

You are going to have to attach your model so the forum users can give you an explanation, the pictures are not enough.  If you do not know how to attach your Fusion 360 follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save to your hard drive. Then use the Attachments section of a forum post to attach it.

[jgranata13]

I think I did this right...

[jhackney1972 · Accepted solution]

Well this one has got me stumped at this point.  What I suggest you do is create a three point construction plane, as shown in the Screencast and move on until someone can either determine a reason you cannot use a 2 edge construction plane.

@jeff_strater  could you have a look at this issue and see if you can create a Plane Between the Two Edges marked in this screen capture.  For that matter between a lot of edges between the vertical body and the horizontal one.  As the original poster has indicated, the edges are parallel as far as I can tell.  Thanks!

[jeff_strater]

no real answers yet.  But, most likely, this is the result of a difference in precision between multiple commands in Fusion.  Most likely between sketch and the plane command.  Sketch, for performance reasons, uses a slightly looser tolerance than the rest of Fusion, and that can sometimes result in these problems.  I did notice this discrepancy:

just a bit over 90.  Looking at the sketch, there is one line that is a bit weird.  If you edit the dimension, you can see that this line is not constrained vertically:

because of a coincident constraint to one of the points on the small circle.  I wonder if this is involved somehow.  Though, fixing this did not fix the plane problem.  Will have to keep digging.

[jeff_strater]

looking at this a little more.  I'm not sure what purpose sketch1 has in this design, but it has some interesting angles defined.  Is that intentional?

For such a simple bracket, I think you'd want everything to be perfectly vertical/horizontal/parallel/perpendicular.

[jgranata13]

sketch1 encodes the geometry of the mounting holes where the bracket will be anchored. They're already drilled and not perfectly square. sketch 2 is a rectangle that approximates the quadrilateral formed by the screw holes, and everything is built off of that (i.e. everything in the bracket is square as you suggest). In other words, sketch1 is only used to make the holes in the bracket line up with the holes on the mounting surface.

[gtprototype]

Perhaps my experience will help isolate the problem.  I discovered this yesterday working on a very simple part and was waiting for my screencast to upload and fully mature before attempting to attach it. 

In the attached file, if you evaluate the first sketch, which includes two center point rectangles, with the measure tool the left sides are parallel and the right sides are not.

RANT ON: I've tried numerous times to attach a screencast resulting only in frustration!  Yes, I read through all the posts telling me how to do it; none of which work.  Why does this continue to be such a problem????

RANT OFF

Here's a LINK

[TheCADWhisperer]

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@gtprototype wrote:

RANT ON: I've tried numerous times to attach a screencast resulting only in frustration!  Yes, I read through all the posts telling me how to do it; none of which work.  Why does this continue to be such a problem????

RANT OFF

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AFAIK they are completely ignoring this Screencast embedding issue.

I have shown how to reproduce the issue and where to look for the cause to resolve the issue, but have been (almost) completely ignored after they got confused.  

https://forums.autodesk.com/t5/community-feedback/your-post-has-been-changed-because-invalid-html-wa...

https://forums.autodesk.com/t5/community-feedback/help-me-there-are-errors-in-this-forum-why-i-cant-...

https://forums.autodesk.com/t5/community-feedback/unable-to-attach-screencast-to-forum-post/td-p/103...

Three of the many many many posts about this ongoing unresolved issue.

[TheCADWhisperer]

@gtprototype 

Back to the parallel, perpendicular, horizontal, vertical sketch issue.

I deleted everything in your file except the two rectangles in Sketch1 and the Extrusion to get the problem to its simplest form.

I then went back and deleted the Vertical on the inner rectangle and replaced with Horizontal on the bottom line and the issue was resolved.  Maybe this will help the sketch team figure out why/how it was measuring as a tiny angle between faces.