Problems with Coincident Lines

[ripberger]

Newbie on Non-commercial version...

I've encountered some behavior with coincident lines that seems problematic ....

Working on a sketch in Design panel. I needed to create a construction line at an offset from an existing line (and perhaps due to lack of knowing a better way), so I create a perpendicular construction line with the desired spacing and then created two lines off the point (one in each direction). In one case I ended up two construction lines overlapping in one place. When using the Circle tool, the pointer would not lock on to an intersection between a normal line and the overlapped part of the construction lines. After deleting both coincident lines and reconstructing a single construction line, it worked normally.

Another case with the same idea about creating an offset construction line as above, but in this case, using the circle tool, got an error and the details said something about the profile was not created because the compute failed. Similar clean up of deleting construction lines and recreating, and it worked thereafter.

Another case where I copied two sketches (copy/paste) into a third and moved them around so that they were touching on one edge. This resulted in four coincident normal lines at the edges  (haven't check to see if somehow there were two on the edge of the source sketches). At any rate, when using the circle tool, the second point would lock on the coincident lines but the program would hang forever. Terminated fusion, re-opened the file, deleted 3 of the 4 lines and it worked OK again.

Whether there are any documented rules about not having coincident lines or not, perhaps the program should either deal with them transparently, or provide a warning about them when created, or at least provide some information when the program trips over them without just hanging or having a non-specific error.

[g-andresen]

Hi,

please create a screencast according to the motto "pictures say more than a thousand words".

In this way, the process can be understood without doubt and, if necessary, hints can be given.

günther

[jeff_strater · Accepted solution]

yes, in general, overlapping sketch geometry is a problem, and is generally something to be avoided.  Agreed that there should be a sketch checker to flag these things, but as of today, nothing like that exists.  So, yes, a best practice is to avoid these kinds of things.

[ripberger]

I think perhaps the "hangs" where actually just the computation taking long enough for me to think it was hung.  I believe a saw a preference for controlling the duration of the computation timeout while I was watching some training video. Once I remembered this, I've let things go on for longer and I think every occurrence of it getting hung up on coincident lines came back and said the computation failed. I also bumped into something (in pull down of Modify?) that said something about "deleting coincident lines" (?) so maybe there's some assists there.

I haven't tried to make a screen cast yet so maybe I'll figure that out if it happens again. In general, I've kept going since I've been able to resolve this situation by deleting the coincident lines, and I don't have a particular instance of it failing right now that I could capture. I also understand how the coincident lines were generated in the sources sketches, and it was intention at the time - but could have been done a different way to avoid.

I'm not surprised you're aware of this, but thought I would pass it on. As a newbie, we often do things in ways that experienced people would avoid by habit and sometimes trip over bugs that are unknown. It's also perhaps helpful to developers to understand what kind of things are not easily understood with the available error messages.  Thanks for the responses. I've been enjoying learn how to use Fusion and have gotten far enough that I can fumble through the things I'm try to create. Cheers.