Automagic Constraint has strange behaviour - bug?

[Drewpan]

Hi All,

Banging out another tutorial to learn new stuff and noticed something a bit strange.

I am drawing a sketch line on the XY plane from the Origin that is 0.8" long at 130 degrees.

When I finish the line I get an automagically created construction line with a horizontal constraint and an

unconstrained point and the line I just created. This unconstrained point can only move along the X axis because of

the horizontal constraint.

My confusion comes about because fusion wants me to put a distance dimension on this point from the Origin in

order to fully constrain the sketch. I was expecting to have to draw my own construction line and make this point

co-incident to lock it to the quadrant I want so that the angle was not floating in space. What I don't understand is

that if fusion is smart enough to guess that my angle was in relation to the X axis, draw a construction line and put

a horizontal constraint on it then why does it A) need a point or B) if it needs a point to internally convince itself

this is in relation to the input angle why does this point it created have to have a distance dimension on it?

d17 is the dimension I just created for the line I DO want.

I don't see why I need to dimension this line fusion created. It would make sense if I created the construction line.

Fusion was smart enough to work out the angle was in relation to the X axis and create a horizontal construction line

so why does it need further input? The length of a construction line is irrelevant.

Cheers

Andrew

[TheCADWhisperer]

Rather than Dimension I would use Equal or Coincident constraint.

[davebYYPCU]

The length of a construction line is irrelevant.

and unconstrained, until it is.

Might help…

[Drewpan]

Hi Guys,

I am not asking how to constrain it, I am wondering why, if it is automagically generated, it has done it this way? Also

since it has done it this way why it needs to be constrained? Fusion has identified that I created a line at an angle to

the X axis. In response to this identification fusion has generated a construction line with a horizontal constraint

and an unconstrained point. Why has it generated the point unconstrained? Fusion created it, it has no purpose that

I will use and since it is a construction line I could enter a distance in parsecs and it wouldn't make any difference to

the end result. It appears to be that this point is collinear with the arc from the point I created so why not generate

it with a dimension of that instead of making me enter a dimension? It just seems strange that fusion is smart but not

too smart in this case.

The dimension I ended up using was equal to the length of my line. Doesn't make any difference because I expected to

constrain it some way but fusion half did the job for me. I am just questioning why it got half way and stopped.

Cheers

Andrew

[TheCADWhisperer]

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@Drewpan wrote:

It just seems strange that fusion is smart but not too smart in this case.

I am just questioning why it got half way and stopped.

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Yes, Fusion should have been smart enough to create your sketch just by you thinking about it.

We aren't there yet...

and why is

Tesla FSD-beta still in Level 2 beta?

[TrippyLighting]

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not bother you when tha@davebYYPCU wrote:

The length of a construction line is irrelevant.

and unconstrained, until it is.

Might help…

---

That is true. And as an experienced user it might simply not bother you when that results in a not fully constrained sketch. But for people new to CAD and Fusion 360 (I am NOT referring to @Drewpan ), this can become a hurdle, evidenced by the number of posts form users who are bound and determined to have every sketch fully defined.   

[davebYYPCU]

Why it is not fully constrained as supplied, Fusion does not have your design intent from the limited input.  

I prefer it stop where it did.

Might help….

[laughingcreek]

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@davebYYPCU wrote:...I prefer it stop where it did.

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Me to.  Fusion doing things for me to be "helpful" is frequently a source of frustration.