Moving a sketch changes its shape

[obious]

Hi All,

Simply put, whenever I select the outline of a sketch to move and then actually move it, it changes its shape. Anyone know why?

In the attached images (before), you can see the outline of what I want to move and then the resulting way the outline is changes after moving. This happens if I move it as well as when I copy & paste and then move it. 

[jhackney1972]

Depending on how you move it, it changes shape because the sketch is not fully constrained.  If you move it by a Window selection, you probably can get away with it.

[obious]

Thanks for the reply. I'll give that a go but any idea how I make the shape constrained? 

[jhackney1972]

You will have to attach your model, containing the sketch, for me to comment on that.  I am sure there is a way, most any sketch can be constrained.  Normally you do not move a sketch, just constrain it in the right position to start.  If you do have to move it, it must be constrained in itself but not to the origin or any other fixed point.

[evanp4509U4JZ]

I frequently have the same problem. We need to move trim patterns to compensate for different machines we trim with. As was said, window select is probably easiest. The sketch changes shape because some part; curve radius center, mirror line, offset original, etc. wasn't selected or some hidden constraint or coinsidense wasn't selected. It can be maddening, especially if you're kinda cluttered. If you select EVERYTHING it will move with some integrity.

[laughingcreek]

Sketching is a fundamental skill for parametric modeling.   It would be time well spent to go through the tutorials on sketching before proceeding.  It would be time well spent if you hope to get decent with fusion. 

[TheCADWhisperer]

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@evanp4509U4JZ wrote:

I frequently have the same problem.

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Then like the OP, you must not be fully defining your sketches.

File>Export and then Attach your *.f3d file here for next step to predictable results.

[obious]

Here's the file. Cheers! 

[TheCADWhisperer]

I was going to fix this for you, but then it occurred to me that most of this should be rather obvious.

There is obvious symmetry left to right, so you only need half of this sketch.

Use Equal (=) constraints rather than repeating dimensions.

You are missing many many obvious dimensions.

Can you put a bit more effort into this before I tackle finishing the clean-up?

(Actually, you are already working too hard, this can be significantly simplified.)

As I start to clean this up - this hole position looks "fishy" to me?

I have found at least a half dozen questionable dimensions in just a few minutes of effort.

Fusion 360 does not have Sketch Blocks, so you will have to develop very disciplined techniques in fully defining  your geometry.  The questionable dimensions would seem to indicate that this might be a worthwhile endeavor.

I'm still finding patterns (or near patterns that might be patterns).

[chrisplyler]

Consider that you have selected several individual sketch elements that you would like to move. Consider that some of them are arcs. I suspect you have NOT also selected the arcs' center points. Naturally, if you try to move an arc, while leaving its center point behind, it will change the radius and orientation of the arc.

You really, really need to go through the beginner tutorials on sketching. You need to learn about properly constraining your sketch elements.

[obious]

Sorry but I don't understand how anything you've said solves or impacts the problem I'm trying to solve. The one thing I can see from what you've suggested is that it using equal constraints would save me time in the future, which in and of itself is of course useful. 

It's worth noting by the way of context (that I should have said before), what I'm trying to create is influenced by the dimensions of each component that I'll be attaching to this panel (once laser cut from perspex) so if you're seeing slightly odd metrics/dimensions, thats a little out of my control. Also, the entire sketch cannot be mirrored down the centre line as a few holes are needed at different locations

[TheCADWhisperer]

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@obious wrote:

Sorry but I don't understand how anything you've said solves or impacts the problem I'm trying to solve.

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OK.

[obious]

I agree, learning the tutorials would be a good idea, truth be told I’ve ‘learnt by doing’ since I started using 360 back in Jan rather than what would be considered the correct approach. 

I’ve tried selecting all arcs (either via Window selection or manual section) and the shape is still modified once I try and move it; I wonder if there’s some hidden arc point somewhere that I’m yet to find 

[chrisplyler]

Ooooo... NOW I see what you're talking about. It flips the two arcs in the corner. I don't know why it does that.

But I do know that if your sketch was a lot simpler and constrained properly, it wouldn't. That's what @TheCADWhisperer  is talking about. He's trying to lead you in the right direction for learning how to get things to work as they should. Dismissing it is not advised, even if it doesn't specifically address your current problem.

Examples:

Stop trying to put every little 2mm fillet into your sketch. It's unnecessary. And it creates issues defining corner-to-corner dimensions, because of course your hard corners are gone.

You're sketch should be definitively related to the origin somehow, preferably in a way that relates to the symmetry that you do have.

Personally, to keep down the clutter, I would have made one sketch for the main shape, a second sketch for the main cutouts, and a third sketch for all the drilled holes.

[obious]

Yea, you're probably right. I do however need to fillet a lot of corners as I'd prefer them round as to being right angled when I have it cut. Please don't misunderstand me, I'm all for being led in the general direction and learning the correct approach rather than just being told but something like this is very frustrating. Apologies if what I've said previously has come across as brash/dismissive. 

I've noticed something rather interesting whilst I try and troubleshoot this myself. The file I attached is a combination of other sketches from other files. The main shape I'm having issues with is actually taken from a body (I've drawn a sketch on a body surface, double click the outline, copy it and then paste it into a new sketch in a new file. 

I've also noticed that if I move it right after pasting, the shape isn't modified by Fusion. However, if I flip the shape (as its imported upside down and back to front for some reason; something else I need to address) and then move it, the instant I do so the corners misbehave themselves. 

[chrisplyler]

Yeah, there is definitely something weird going on that I can't explain.

I just know that with the right methodology, it never happens to me. With the right methodology, I never need to use the Move tool on sketch elements at all.

You don't need to fillet IN THE SKETCH in order to have your part cut with fillets. Extrude the hard cornered sketch, and then fillet the resulting 3D body where desired.