Cant change driving dimension

[michaelASVN6]

I have had this happen a few times now and it is so incredibly frustrating I decided to post here in my rage. 

I have a simple undefined sketch that needs one dimension on say the height to make it fully constrained. 

I can drag the sketch freely up or down and all other dimensioned items move freely with it. 

I then move the sketch height close to where I need it and add a dimension to drive the height - lets say at 32mm. 

The sketch is then fully defined.

However, when I go to modify it to 30mm it says it can't do it even though it is a driving dimension.

Yet, if I deleted this one dimension, it goes back to being undefined and I could manually drag it down to 15mm if I wanted. 

After deleting a bunch of dimensions and constraints just to simplify it even more and to try and fix it, I could change the height dimension from 30mm up to 35mm but then not back down to 30 which I changed it from. 

I also have it happen where a sketch appears all black yet it can be dragged around.

Or the sketch is fully constrained yet parts of it are still blue. 

I am confident in what I have modelled and have even redrawn things like this before in F360 in case I messed something up. I could even understand if these were complicated sketches with heaps of constraints but these are pretty simple sketches for aluminium profiles I have done 1000 times before on other software over the last 20 years.  

I love a lot of other things about the program and am self employed using it professionally but I just cant trust the program on the most basic thing it needs to do let alone recommend it to companies who ask me.  Before the key benefit was price entry to market but even now it's getting over $1000 AUD making it harder to justify. 

[g-andresen]

Hi,

please show such a process in a screencast and share the file

File > export > save as f3d on local drive  > attach to post

günther

[davebYYPCU]

When you can't read all the dimensions, then it is not a simple or simplified sketch.

The more you put in it, the hard it is for Fusion to constrain, without errors.

Do yourself a favour and delete one half of the sketch, use the origin for symmetry, and mirror the body you used the sketch for.

Might help...

[TheCADWhisperer]

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@michaelASVN6 wrote:

…I could even understand if these were complicated sketches with heaps of constraints but these are pretty simple sketches

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@michaelASVN6 
I see a complex computationally expensive sketch with way too many unnecessary constraints.

Thin features and mirror of features rather than duplication of sketch elements is the most computationally efficient technique.

[michaelASVN6]

@michaelASVN6 

There are only 17 dimensions - surely that is a simple sketch? Even if I deleted half and mirrored it I would have to add even more dimensions back in. Mirroring only works if you know the part will end up being symmetric, which I don't know at this stage. 

I can read all the dimensions just fine on my computer too, that's pic is just a bit zoomed out to communicate the simplicity of the shape. 

[michaelASVN6]

@TheCADWhisperer
I see a complex computationally expensive sketch with way too many unnecessary constraints.
Thin features and mirror of features rather than duplication of sketch elements is the most computationally efficient technique.
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The majority of those constraints are put there by Fusion when sketching (vert, horiz, and perp). I only added in other constraints necessary to fully define it without adding redundant dimensions (co-linear and equal lengths).

Honestly something like solidworks 2016 can handle this profile and exactly what I have done with ease so I am a bit lost as to why people think it's super complicated?

Sorry I don't know how to quote someone properly here yet.

[TheCADWhisperer]

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@michaelASVN6 wrote:
Honestly something like solidworks 2016 can handle this profile and exactly what I have done with ease so I am a bit lost as to why people think it's super complicated?

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I have been an CSWP since 2007.

This is unnecessarily complex sketch in SolidWorks too.

Thin Features simplify sketching.

Mirror of Features simplify sketching.

If you don't know if the end design will have symmetry - all the more reason to use computationally efficient sketching techniques.

[g-andresen]

Hi,

Share the file for a more focused discussion.

günther

[michaelASVN6]

Solidworks has a breeze with sketches significantly more complicated than this so to say it is unnecessarily complex for that is just hyperbole.

Thin features work well if you know the walls are equal thickness which they aren't in this case. In order to know their thickness I need to sketch it first too so it makes it redundant to then extrude thin features and fraught with error if I were to change the sketch again later.
Again, mirroring only works if you know the part will end up being mirrored. Yes this looks mirrored now but doesn't mean I knew that at the start or that it will be the case later.

To me sketch then extrude sounds simplest with the least chance for errors.
Sketch then thin feature, thin feature, thin feature, mirror body, seems like it would take longer and be more likely to go wrong.

[TheCADWhisperer]

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@michaelASVN6 wrote:
Solidworks has a breeze with sketches significantly more complicated than this so to say it is unnecessarily complex for that is just hyperbole.

Thin features work well if you know the walls are equal thickness which they aren't in this case. 

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Computationally efficient sketching techniques are universal across all history-based MCAD softwares.

Your sketch is relatively simple (even if it could be significantly simplified) so I can only assume that you have introduced a logic error that you have not identified.

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

You can have more than one Thin Feature in a design.

[michaelASVN6]

Here's a video linked below.

[michaelASVN6]

Okay here's the file. Sketch 2 is where the error happens. I did notice that if I delete the other 2 bodies the sketch would then work. 

[g-andresen]

Hi,

I had asked for a f3d file for this purpose.

günther