Unconstrained pencil icon on sketch that appears constrained

[Anonymous]

One sketch in my project ('Body top' on the attached file) shows a persistent pencil icon indicating it's unconstrained, but all lines are black, there are no visible white ends, and I couldn't find any moveable parts on the design.

I'm a beginner at Fusion, this is my first project on my own after finishing the 3d modeling Coursera class. Is it really necessary for the lock icon to show on every sketch? I mean it's a bit unnerving to not see it there, but I can handle.

[wmhazzard]

Fusion has problems with sketching. I could not find anything that is not constrained in your sketch and I have seen quite a few simple sketches that show as constrained and are not and I have seen ones that do not show constrained but are. If you can't find any reason that the sketch is not constrained then don't worry about it too much. Maybe some day Audodesk will do some work on the sketch environment. 

[Phil.E · Accepted solution]

I'm not sure why this is already marked solved, but your sketch is underconstrained at these two points.

Here is why.

• At both point A and B you have multiple overlapping line segments.
• These are constrained (somewhat confusingly) by tangent constraints. 
• In both places you need to delete some lines and use only one line there. I was able to achieve this without removing or replacing any other dimensions or constraints.

In 12 years experience as a CAD teacher, I can say this must have happened by two things. Drawing lots of geometry and trimming it. That is what abandons little line segments that lay on top of each other. And the tangent constraints seem like an attempt to get the sketch fully constrained, without thought to how they add design intent. Is there a design driven reason all these line segments are overlapping and have been given tangent relationships? 

Anyway, thanks for the design. I don't think Fusion's sketch engine is doing anything wrong here.

[TheCADWhisperer]

@Anonymous 

In addition to the other comments - my 2 cents...

I (almost) never use dimensions that cannot be measured out on the shop floor.  I suspect this was just an effort to fully constrain, but I would have found a more logical dimension (or better yet a logical geometry constraint).

And I would seldom have duplicated dimensions.  I would constrain in such a way that a change in one dimension changes all related geometry (for each group circled above).  (At the very least - I would make as functions if there was a chance that I might alter separately some time in the future.)

Edit:  Hmmm, this prompted me to go back and look at your other sketches which I had not done previously.

They all look good and logical.

[Anonymous]

Whoa, thanks a lot for that. You're completely right, I was trimming a lot of offset lines before noticing that was actually creating a mess, also joining lines by creating new ones and making them collinear. There really wasn't a design reason for this, just me not knowing the best practices. By the way, any tips on how to find those small unconstrained elements? Besides not creating them in the first place, that is.

[Phil.E]

Here is the tip:

I used the ground constraint.

You can try it on your sketch if it's not yet fixed, or just open the old one from your version history to try it out.

1. Edit the sketch you posted
2. Start the ground constraint (the lock icon)
3. Box select about half the sketch.  
   1. Does the sketch icon change to fully constrained in the browser?
   2. If not continue to ground (lock) portions of the sketch until you see the icon change to fully constrained.
4. Take note of the area you need to fix, then undo all the locking and fix the area.
   1. Does the sketch icon change to fully constrained in the browser?
   2. If not, do the steps again.

To find line segments that lie on top of each other: Use the "all in" selection method.

1. Select a box area by moving from left to right with the mouse. This produces  a "solid" box compared to moving the other direction.
2. This kind of selection only selects what is "all the way inside" the selection box.

This way you can find small items - they will be all the way inside the box while the longer lines are not. 

[g-andresen]

Hi,

try this way:

günther

[Anonymous]

@TheCADWhispererI tried to not use those weird dimensions, but I couldn't find any other way to constrain those angled lines connecting two constrained edges. They're just supposed to be the shortest path between the two points, without known dimensions or angles. Any suggestions on what to do there? I'll also try to clean up the other dimensions.

[Anonymous]

@Phil.EThanks once again, that was all incredibly helpful.