Constraining Construction Lines

[Drewpan]

Hi All,

I have noticed what to me is annoying behaviour.

Ever since I learned that one way to see if a Sketch is Constrained is to check the little Lock Icon on the Sketch I have tried to nail down all of my Constraints before moving on. Usually all the lines going Black is good enough but sometimes a floating Point or such will turn Black but there is no Lock.(Cheers from @TheCADWhisperer and @davebYYPCU - I know, I was VERY Raw when I first posted here 😎)

Something I have noticed is that when I draw a Construction Line, Fusion insists that I give it a constrained Length. Now I understand that there are times when you may want this. I understand when I might want other constraints like Mid-points locked to the Origin or Tangent to something. My real question is what if I have the Constraints I want and I just want a Construction Line in a particular place?

Most commonly I like to have a nice vertical and horizontal Construction Line through the Origin. I don't care how long it is, I just want it through the Origin and Perpendicular. It doesn't matter how long it is, it is only there for my own reference. My Sketch however will not Lock until I have put Constrained Lengths on these lines.

I do get it that an ACTUAL Line needs to be Constrained. My point here is that a Construction Line is only for Reference so why Constrain it when you do not need to?

Any thoughts?

Cheers

Andrew

[davebYYPCU]

Design specific, you are the master of living with fully constrained or not.  

When you progress to changing designs by parameter change, you will appreciate a fully constrained sketch.

Construction line for your own pleasure, seems like excess work if not being constrained, and not being constrained is because it is just there because. 

My view - if the construction article is not doing a job, it's clutter.

Might help...

[g-andresen · Accepted solution]

Hi,

1. the symbol does not mean locked, but "fully defined".
2. whether we say something about it or not, it is specified by the developers that construction lines must be defined like any other element.

günther

[John_Wright]

Sometimes the length of a construction line constrains parts of a sketch. It would be unhelpful if they were always infinitely long.

Take the image of the spline below....the length of the construction lines are critical to shape of the spline.

[HughesTooling]

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@Drewpan wrote:

Hi All,

Most commonly I like to have a nice vertical and horizontal Construction Line through the Origin. I don't care how long it is, I just want it through the Origin and Perpendicular. It doesn't matter how long it is, it is only there for my own reference. My Sketch however will not Lock until I have put Constrained Lengths on these lines.

Any thoughts?

Cheers

Andrew

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I remember a while back someone complaining about inaccuracies in a design and blaming it on Fusion. What I found was in their first sketch they'd created what looked like a vertical line but it was off by a very small amount. As it was the first sketch everything from that point that referenced that line was also off (was used for a mirror line in the sketch). Now if the sketch was fully constrained before closing you'd find the missing constraint and save a lot of headaches! 

I find most of the time the construction line end point can be constrained to other geometry and the sketch just ends up looking neater rather than having infinet construction lines.

Mark

[jeff_strater]

This is a good question.  There are multiple ways that construction lines can get used in a design.  The usage you are implying is an unbounded construction line.  But, there are valid workflows where a bounded construction line is quite useful.  That is:  the construction line is used not just for direction or as a measurement datum, but has a definite length.  Imagine a construction rectangle, where you want to, say, measure from one corner of the rectangle.

Fusion does not support unbounded construction lines in a sketch (though it has been requested).  All lines in a sketch are the same (bounded), so yes, if you want to fully constrain your sketch, then, yes, you will have to constrain the endpoints of your lines.

[Drewpan]

Hi,

I agree that there are times that I either want or need to Constrain a Construction line. Part of the reason Construction lines are there are for that very purpose. I am more asking about lines that are not there for any specific purpose other than to aid ME while I am drawing.

Since I started my CAD journey with AutoCAD, and didn't know about Constraints, I would typically set my Construction lines on a separate Layer. Then I would either turn them On or Off as needed or simply delete them after. The only Construction lines I would leave on the actual final Drawing would be Centre lines or those others required under the AS1100 Australian Drawing Standard.

Cheers

Andrew