Center rectangle adjust after drawing

[Anonymous]

I've been meaning to post for a while because this drives me mad every model I attempt to make.

In the sketch interface, when I create a 'Center Rectangle' and pull out from the middle I get a perfectly symmetrical square shape as you would expect...However when I try to grab a point after drawing, from one of the sides to slightly adjust it only modifies one side...I've tried adding symmetry constraint but it throws out an error such as 'Sketch over constrained' or doesn't work as I expect... and tbh I end up just deleting the rectangle and redrawing the shape. But because I am in this position a lot, I thought I'd post the question to hopefully get a solution.

To explain what I'm trying to achieve, imagine you have a shape in photoshop. You can select the layer and transform it and if you press ALT while doing so it scales from its center point so scales the layer uniformly. It takes me a lot longer to throw down sketches as I tend to redo parts a lot because of this and it's so frustrating.

[TheCADWhisperer]

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@Anonymous wrote:

In the sketch interface, when I create a 'Center Rectangle' and pull out from the middle I get a perfectly symmetrical square shape as you would expect....

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Actually, I would expect to get a perfectly symmetrical rectangle, not a square.

Are you using the Origin Center Point to anchor the center point of the rectangle?

Can you post a Screencast recording of the behavior that you see?

Can you File>Export and then Attach a *.f3d file that exhibits the behavior you see?

[Anonymous]

Thanks for the reply.

No the drawing of the shape isn't the frustration, it's when I make adjustments after. The behavior I'm looking for is when you draw a center rectangle on the origin, you adjust one side it reflects on the other.

Here's if I don't draw on the origin, the center rectangle acts like any other rectangle after I've drawn it out..

[g-andresen]

Hi,

the center has to be referenced.

günther

[whittakerdw]

As @g-andresen said the rectangle needs to be referenced. The main way I do this is by dimensioning the center of the rectangle from the center point of the plane. When this is dimensioned, it knows that the center point is fixed and not intended to move.

[whittakerdw]

And the reason it doesn't move the center when you start at the center point of the plane is because fusion knows that you intended the center to be at (0,0). Hope this helps.

[TheCADWhisperer]

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@Anonymous wrote: 

Here's if I don't draw on the origin, .... 

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If you don't place on the origin - then it is logically floating is space.

You need to give two dimensions to locate the center in space so that it is not free floating in space or Project some other existing Geometry and Coincident.

[melvinbrian3d]

In Your ScreenCast i See You Dont Have Any Reference Constraint With The Origin.... You Need To Draw a Vertical Line From The Origin, Then Do The Center Rectangle Over That Line.

[scottyh72]

If you pick a plane, and then a center point, you have in fact located the rectangle in 3d space.  Why in any universe would you also have to draw an arbitrary line on the z axis to then locate a center rectangle in space that has already been positioned in 3d space?  Makes absolutely no sense.  When you pick a center, rectangle, you are already telling the software that the rectangle is constrained around the center point. 

[TheCADWhisperer]

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@scottyh72 wrote:

If you pick a plane, and then a center point, you have in fact located the rectangle in 3d space.  Why in any universe would you also have to draw an arbitrary line on the z axis to then locate a center rectangle in space that has already been positioned in 3d space?  Makes absolutely no sense.  When you pick a center, rectangle, you are already telling the software that the rectangle is constrained around the center point. 

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I don't know what any of this means.

I do not see any arbitrary lines?

Can you create a Screencast Recording illustrating  your issue?

AFAIK in the CAD world the Origin is the center of the CAD 3D space universe. Any other location is space must be explicitly identified or it is transitory.

[scottyh72]

Yet when you set the center of the "center rectangle" at the origin, it
then moves around arbitrarily. If you draw a construction line through the
origin perpendicular to the plane you draw the rectangle, then the origin
is no longer arbitrary. The line will also change whether you can edit the
center rectangle properly (symmetrically). Why? A silly construction line
sets the origin, while a center point to a rectangle does not?

[TheCADWhisperer]

I don't understand anything that you have written.

Can you create a Screencast Recording illustrating your issue?  (This is a binary yes/no question.)

I generally have an easier time understanding geometry than written text.

[chrisplyler]

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@scottyh72 wrote:

If you pick a plane, and then a center point, you have in fact located the rectangle in 3d space.  Why in any universe would you also have to draw an arbitrary line on the z axis to then locate a center rectangle in space that has already been positioned in 3d space?  Makes absolutely no sense.  When you pick a center, rectangle, you are already telling the software that the rectangle is constrained around the center point. 

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You've located it, but not constrained that location. When you drag only one side and get the behavior you are complaining about, you'll notice that the center point STILL stays centered, it's just moved half the distance that you dragged the side.

How is Fusion supposed to know you want the center point locked in place unless you LOCK it in place. You may do this by constraining it to the origin point, to some other sketch element, or by using the Fix constraint on it. That last one may give you what you want. Sketch your center point rectangle, then Fix its center point.

[chrisplyler]

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@scottyh72 wrote:
Yet when you set the center of the "center rectangle" at the origin, it
then moves around arbitrarily. If you draw a construction line through the
origin perpendicular to the plane you draw the rectangle, then the origin
is no longer arbitrary. The line will also change whether you can edit the
center rectangle properly (symmetrically). Why? A silly construction line
sets the origin, while a center point to a rectangle does not?

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This doesn't make any sense. If you activate the center point rectangle tool, and then begin placing it by clicking ON the origin point, then the center point of the rectangle will automatically get a Coincident restraint with that origin point. If it doesn't, you're doing something wrong.

[scottyh72]

If I edit a (center, circle), it does not move.  Center point stays, circle gets bigger or smaller.  I did not constrain anything.

If I edit a (center, rectangle), only one side moves, along with the center point.  

Both drawn with the same technique.  Both with only 2 points of reference, and no constraint.  Two totally different outcomes.  

Please explain why the rectangle needs to be constrained, yet the circle does not.  

[TrippyLighting]

If you start both, a center point circle or a center point rectangle by selecting the sketch origin their centers are both constrained the sketch origin. 

[davebYYPCU]

Centre Circle is created with just 2 entities, centre point and a radius  (only one or the other to manipulate)

Guess how many entities exist in the centre rectangle.  (I bid 16)

[laughingcreek]

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@scottyh72 wrote:

If I edit a (center, circle), it does not move.  Center point stays, circle gets bigger or smaller.  I did not constrain anything.

If I edit a (center, rectangle), only one side moves, along with the center point.  

Both drawn with the same technique.  Both with only 2 points of reference, and no constraint.  Two totally different outcomes.  

Please explain why the rectangle needs to be constrained, yet the circle does not.  

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No mater how you draw it, a circle is defined by it's center point and radius. 

like wise, no mater how you draw it, a rectangle is defined by the 4 lines that are constrained at their endpoints with the coincidence and perpendicular constraints.

The "center point" in the rectangle isn't part of the definition, it's just a construct to help you draw and constrain it.  If you draw a circle using the 2 -point or 3 point method, it will still behave the same as what your seeing.  If you draw a rectangle by any other method (even drawing it with individual lines), it will all behave the way your seeing it.