Part sketch constraint issue (over defined)

[TravisJoe]

I apologize if this is redundant, but it seems most constraint issues are slightly different and/or old. 

The basic concept

I created a part with references to another part in my assembly. I wanted to changed the part so I deleted the two constraints (collinear and coincident). When trying to apply new dimensions it suddenly started to say the sketch was over constrained. This is strange because I have deleted constraints and able to move the sketch freely. See screen cast for better understanding.

I understand the state in Fusion360, but find this as a very frustrating speed bump while trying to work on my first major project in Fusion360. I am assuming I will likely have to delete the part and start over so I can continue my work.

[HughesTooling]

A couple of thoughts, One when an offset is involved there seems to be more problems. Two sometimes you'll need to turn off constraint colouring, not sure you are using it, I use a different colour scheme.

You might need to upload a sketch to help with finding bugs, as it's not obvious how many of the lines are offset.

Mark

[HughesTooling]

Here's an f3d with the same setup, I think. It is the offset causing the problem, select the offset icon and delete then you can add the dimension.

Mark

[HughesTooling]

Here's a short screencast that shows the problem's caused when you add the 2 connecting lines between the the offset lines.

Mark

[TravisJoe]

Thanks for the amazing speed in responding to my issue. It also makes me happy that it is identified and repeatable, which can often be the hardest part in software.

What does worry and confuse me is why is this an issue. This seems pretty fundamental based on my years of use of parametric modeling. Is this reported as a bug?

To make this worse, the reason I was designing a channel like that is to have sheetmetal part placeholders until the sheetmetal functionality is released, which is hopefully soon. I know there is other ways to design the same part, but to me that is not a good enough excuse.

Thanks again for the great help, at least now I know!

[Anonymous]

Hi Mark,

A clue as to what could be wrong, and I'm sure there is something wrong with the code, is that even before you close the shape and try to dimension any offset line, the over-constrained error comes up. I am not a programmer but it seems the offset curve is somehow "fixing" the original shape dimensions, a supposition which is supported by the fact that when you drag one of the offset lines - the entire sketch moves, whereas when you drag one of the original lines the shape changes accordingly.

Just an observation. What do you think??

Regards

John

[FrankCao]

Thanks TravisJoe for posting the problem. Also thanks HughesTooling to help reproduce this problem in a simpler model!   Really appreciated!

Current Fusion sketch would have some problems when solving with sketch offset geometries. We are also actively watching the forums to gather such kind of issues and are doing more testing with Sketch offset. Now this problem is tracked internally as FUS-27319 and developer has started to take a look at this issue. Hopefully we will try to solve the problem with offset soon. 

Thanks,

Frank