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Where should the sketch be on my base feature?

7 REPLIES 7
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Message 1 of 8
rickduley
531 Views, 7 Replies

Where should the sketch be on my base feature?

I am starting a drawing exercise from a textbook.  The base feature is a rectangle, drawn in the XZ Plane, 300x150mm, extruded 25mm.

By default the extrusion would be upward, leaving the sketch at the bottom.  Why?

 

My instinct is to have the sketch on the top so I can draw additions directly on it.

7 REPLIES 7
Message 2 of 8
TheCADWhisperer
in reply to: rickduley

When creating the extrusion you can click the direction arrow to flip the direction.

You take control of the software for your design intent.

Message 3 of 8
johnsonshiue
in reply to: rickduley

Hi! The default direction is just a choice. It has to be persistent and predictable. The default Extrusion direction is consistent with the normal direction of the sketch plane, i.e. right-hand rule cross product of X and Y of the sketch (opposite to the direction when you look at the sketch). The user can flip the direction at will. If the behavior you see is different from the above description, I would like to take a look at the case. Thanks!



Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer
Message 4 of 8
blair
in reply to: johnsonshiue

It goes way back, Up is in the Positive direction. In buildings, you have a Floor Plan, everything is in the Up/Positive direction. Footings, for buildings are in the Up/Positive direction.

 

You can work in the negitive direction, doesn't really matter too much for most applications.


Inventor 2020, In-Cad, Simulation Mechanical

Just insert the picture rather than attaching it as a file
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Message 5 of 8
rickduley
in reply to: johnsonshiue

Hi johnsonshiue

 

I am afraid I do not understand this at all:

"...  right-hand rule cross product of X and Y of the sketch (opposite to the direction when you look at the sketch)."

 

Would you mind explaining this to someone who doesn't (yet) speak Inventor?

 

Thanks

Message 6 of 8
rickduley
in reply to: blair

Hi blair

 

Hmmmm!

I was just thinking back to the days (of yore) when I did woodwork at Elementary School.

I always did my marking out on the top of the piece of wood.  When I marked something out on the bottom of the piece of wood, the bottom became the top.

 

I think that idea is older than munti-storey buildings, and I feel it is more relevant to 3D-modelling for mechanical parts. Smiley Wink  BTW: I wasn't aware that people use Inventor for architectural drafting.  Personally, I would be inclined to stick with CAD for that.

Message 7 of 8
johnsonshiue
in reply to: rickduley

Hi! The right-hand rule is a simple way to determine the direction of a cross product. Simply make sure four fingers of your right hand (except the thumb) point in X-axis direction. Then fold the four fingers to Y-axis direction. Now, the thumb-up direction should be Z-axis direction, which is also the normal direction for XY plane.

http://en.wikipedia.org/wiki/Right-hand_rule

Thanks!

 



Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer
Message 8 of 8
rickduley
in reply to: johnsonshiue

Really?

 

Simply make sure four fingers of your right hand (except the thumb) point in X-axis direction. Then fold the four fingers to Y-axis direction. Now, the thumb-up direction should be Z-axis direction, which is also the normal direction for XY plane.

 

You must have a very mobile wrist.  I compare what you say here to the axis icon in Inventor

_Axis_Icon_Inventor.jpg

 

and I would have to be a contortionist.  Even then it only works palm-up!

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