Method To Find Missing Constraints

[GoremanX]

I've done a search in these forums and come up empty. Other people have had a similar question before, but the answers were unsatisfactory.

I find that I spend a lot of time looking for missing constraints in sketches. It LOOKS like my sketch is fully constrained, every line is black, and yet the lock icon still doesn't show up for the sketch. This happens very frequently. Sometimes it's because of an extraneous point that's hiding behind another point. Sometimes it's because of a construction line way off the screen somewhere. Sometimes something is constrained "enough" to be black, but still have 1 degree of freedom that I need to discover by pulling on the right point at the right angle. Finding these things is a massive waste of time. There must be a better way than to yank every **** line and point in a sketch and hope to find the missing link.

Another issue I'm having is figuring out which constraint icon refers to which constraint. If I highlight a point, it can have multiple "coincident" constraints. But which one refers to the constraint that joins two lines together, and which one refers to the one that keeps a point locked to another point? So far, the only method I've figured out is to randomly delete a constraint and hope for the best, then if I picked wrong, click "undo" and try again. There has to be a better way...

In FreeCAD, I have a list of all my sketch lines in a pane on the left, and I can select each line from the list and figure out whether it's constrained and how. It also keeps track of how many degrees of freedom remain in the sketch, and allows me to highlight any or all of them with the push of a button. Is there something similar in Fusion 360 that I haven't learned about yet?

[etfrench]

@jeff_strater It seems to be broken🤔  I checked it in one file and it worked.  When I changed to another file, it didn't.  It also didn't start working after restarting Fusion 360.  p.s. This youtube video  shows it working a month ago.

[jhackney1972]

In your Text Command box, change the type of entry to TXT and not PY, on the far right of the entry line, and it will work fine.

[etfrench]

I wonder how that got changed🙄

[rjeAT6XG]

Giving this a bump as I just had a bunch of sketches lose references again.  I fixed the yellow in this sketch, but it still says something is missing, but I can't find it...yet.  It would be great if ALL the references turned yellow and visible.  Even better if there was another visual signal (pointer?  red circles?). 

[jhackney1972]

Attach your model for the Forum users to look at.  If you do not know how to attach your Fusion 360 model follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save as a F3D or F3Z file to your hard drive. Then use the Attachments section, of a forum post, to attach it.

[Drewpan]

Hi,

While following this message string I knew I had seen:

"In Text Commands type Sketch.ShowUnderconstrained if you still have not fully constrained the sketch."

in this message: https://forums.autodesk.com/t5/fusion-360-design-validate/no-way-to-turn-this-blue-lines-to-blacklis...

I should have read this whole string first as I was looking for it to post a reply here.

One thing I did discover is that - if there exists a list of Commands like Sketch.ShowUnderconstrained, then

WHERE in the AutoDesk Documentation is it? I could not find one anywhere. The nearest I could find was here

https://help.autodesk.com/view/fusion360/ENU/?guid=ECD-ENTER-CMDS but that seems to be specific to

Fusion Electronics commands. The only other reference was the above Forum Post.

Does a Command List of commands that can be entered into TEXT COMMANDS exist? If so where, and an

explanation on how to use them?

Cheers

Andrew

[davebYYPCU]

open Text commands. Resize the panel to quite large.

type the (question mark)   ? - press enter.

Might help....

[rjeAT6XG]

I need to add a signature that says everything I'm working on is proprietary and that I can't post it...

It isn't the constraining that's my typical problem, although that could be communicated more clearly.  It's more the lost references.  I seem to find the first 4-5 references easily and then there will be a vertex somewhere that I can't find.

I did end up solving this sketch by just replacing the reference plane.  Oddly, it didn't prompt that the reference plane had been lost.  I started to replace the reference planes further down my design history and that actually solved most of the reference issues.

Re:  text commands.  I miss DOS and love opening the text command, but it's 2023.  We shouldn't be relying on text commands for a CAD software!

[MattPerez314]

No there isn't as the text commands aren't really a part of the software 🙂  

There are some handy ones in there but its mostly trial and error.  There is a repair sketch one that can deal with small gaps, you can get sketch info, there is supposed to be a constraint analysis tool but i haven't really been able to get it to work.

On the original topic of this, when you have a sketch with broken references(which i think a few users have mentioned in replies) you can right-click on the sketch and manage lost projections.  You can break the link, re-link it and a few other options.  There is a checkbox to Fade Other Geometry which is nice.

A year or so ago i made a video on using text commands in the API so if there is a command you use all the time you can set up a simple script to a hotkey and run it that way.

https://youtu.be/MDl4YmCFDGU?si=TFePXnAXHBccpamS&t=746

[kandennti]

Hi @GoremanX -San.

We have created and published a function to highlight sketch elements with missing constraints.

This is the "Sketch Analysis" command of the add-in.

https://github.com/kantoku-code/Fusion360_SketchToolPlus/tree/main 

We would be happy to help you.

[autodesk_comC6PHL]

Hi @kandennti 

Your 'Sketch Analysis' command is perfect.

Kudos to you!

[waynelouvier]

Yes, this is the answer. Everyone should make a note of this!

[waynelouvier]

It should also identify (without any specificity) the geometries that are "under constrained." For example, my current unconstrained bit shows this:

"Under constrained points: 2, under constrained curves: 1" So, at least I know I'm looking for two points and a curve. That's usually enough for me to get it fixed. Good luck.

[waynelouvier]

I've gone as far as saving the text to one of my assignable keyboard keys. Very useful.