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Rotating 3D objects - not that easy?
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* September 02, 2010, 07:40:21 AM
I struggle to get a neat way of rotating 3D objects.

What I want to achieve is to have a fail safe method to be able to rotate any 3D object e.g. box, extruded rectangle, etc, by selecting one of its sides and rotate it around that side for a specific angle.

When I create 3D objects and as soon as the entity CS is not the same as the WCS, controlled rotation is not possible or very difficult.

What I tried is the following:

An example:
Step 1: Construct an rectangle in 2D.  Rotate it through say a angle of 20 degrees. When selected it is selected according to WCS.  The selector box is not a fit of the rotated rectangle.
Step 2: Extrude the rectangle with 3D tools.  Select the 3D object.  The selector box is once again not aligned with the constructed 3D box.
Step 3: Align selector box with 3D object. This can be done as follows:  Select work plane by 3 points and place the point on your box.  Select the object. To align the selector box right click mouse and choose Selector 3D properties.  Select User CS and click OK.  The selector box is now alligned with our 3D box.
Step4: Inputing changes in the input selector for the angles do not react as expectation.  It seems as if only one of the angles seems to operate correctly.

What I want to achieve is to have a fail safe method to be able to rotate any 3D object e.g. box, extruded rectangle, etc, by selecting one of its sides and rotate it around that side for a specific angle.

I attached the plain box and rectangle to this mail.

Red line is rotating axis while the blue circle indicate the rotation.  Rotate the box by 20 Degrees. 

When using the rotating bars, Rot x, Rot Y and Rot Z changes - this is my problem how can this be if I only want to change one by 20 degrees?

Is there an easy solution for this?

In autocad this is so easy, you select the 3D object, select the side, and type the angle of rotation and it is done.

Thanks

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* September 02, 2010, 08:54:07 AM
#1
I never have this problem because I build all my 3D object relative to the XYZ planes then rotate the 3D object.

Therefore in your example, Step 1 you would construct the 2D rectangle then extrude it.

Step 2 you would rotate the 3D solid 20deg.  Then you only need to change the reference point and it would function as you would expect.  No need to change workplanes etc...

However I typically stay away from extruded objects as I find them more difficult to modify after the fact.  I usually use blocks, cylinders, cones etc...  first,  if the geometry allows.
« Last Edit: September 02, 2010, 08:56:06 AM by Johnny_Law »

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* September 02, 2010, 09:03:54 AM
#2
I think you will be helped by employing "Edit Reference Point" SEKE = D.  Place the reference point at the point of rotation (at a vertex of the side, e.g.) and have at it.

Wayne

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* September 02, 2010, 12:04:53 PM
#3
1. Click the Selector 3D Properties icon on your Inspector Bar and be sure that both Extents CS and Coordinate System are set to "User CS."

2. Go to Workspace|Workplane and choose "By Z Axis" (or -- highly recommended -- place the Workplane Toolbar on your desktop and click the "WorkPlane By Z Axis" button). Then vertex-snap on each end of the edge about which you want to rotate the object. This creates a new Workplane whose Z axis corresponds to that edge.

3. Relocate the object's Reference Point to one end of that edge.

4. Select the object; TAB to the Rot Z field of the Inspector Bar; type the number of degrees to be rotated; press Enter. If the object rotates in the wrong direction, Undo the operation and do it again, this time placing a minus sign in front of the Rot Z value.

Henry H
« Last Edit: September 02, 2010, 12:08:25 PM by Henry Hubich »

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* September 03, 2010, 02:01:18 AM
#4
Hi Henry

Thanks for the excellent answer, short, sweet and spot on.

I never saw the coordinate system selectors in the Select Properties window.

Could I be so bold as to ask you to give a short description of the functions of the 4 Extents CS' and the three Coordinate System options? ;D

Much appreciated.

Jacobus

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* September 03, 2010, 12:11:51 PM
#5
Hi Henry

Thanks for the excellent answer, short, sweet and spot on.

I never saw the coordinate system selectors in the Select Properties window.

Could I be so bold as to ask you to give a short description of the functions of the 4 Extents CS' and the three Coordinate System options? ;D

Much appreciated.

Jacobus

I was afraid you were gonna ask that. Truth is, I'm not entirely sure :-(

Henry H

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September 03, 2010, 03:14:06 PM
#6
Could I be so bold as to ask you to give a short description of the functions of the 4 Extents CS' and the three Coordinate System options? ;D

It's one of those things that I think nobody thinks about unless they're in the middle of doing something; in other words, we usually don't remember.   ;)    

The top half of the menu (the Extents CS) has to do with the orientation of the selector shell that you see around an object that is selected.  If you want to see the effects of this you can draw a 3D box (while in an isometric view), then rotate it 15 degrees (or so) in the Z axis.  With the object still selected, proceed through the various "Entity CS" options, clicking 'Okay' in between choices.  You'll notice how the shell changes in appearance, along with the XYZ handles.

The lower half of the menu concerns the Inspector Bar (what shows up in the text entry boxes, and this is where things get confusing, since the selector shell ("Entity CS") and Inspector bar work differently together, depending on the mixture of settings.

Usually, if you're manipulating objects relative to the default workplane (World CS), you can use World CS/World CS.  If you're moving an object relative to itself (say, because it's already been rotated and positioned differently than when it was first created), you can do Entity CS/Extents CS.  Or if you need to shift an object in some non-obvious direction, you'll probably need to change the current CS and enable User CS/User CS in the 3D selector menu.

And for a different example, you may want to see how far you rotated that object a few steps back (relative to the default workplane), so you'll use Entity CS/World CS.

Realistically, I won't even remember what I just typed out while I'm building my next 3D TurboCAD model.  So, the thing to do is really just trial and error, and you'll eventually find yourself tending toward different things as situations warrant.


« Last Edit: September 06, 2010, 05:52:28 AM by Josh T. »

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Josh T.
meatballrocketry.com
TC Pro 18.2 & Platinum 2016


* September 05, 2010, 11:10:09 PM
#7
Thanks Josh T. and Henry Hubich.

My immediate need was addressed and it seems as if trial and error is the way to go.

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* September 06, 2010, 05:33:23 AM
#8
Could I be so bold as to ask you to give a short description of the functions of the 4 Extents CS' and the three Coordinate System options? ;D

It's one of those things that I think nobody thinks about unless they're in the middle of doing something; in other words, we usually don't remember.   ;)     



Thank you Josh, This is one of the inherent systems that we all utilize to some degree and in our own combination's, but I believe yours is the clearest synopsis and explanation I have heard here to date. Very helpful !  -  Al

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September 06, 2010, 05:55:03 AM
#9
Thank you Josh, This is one of the inherent systems that we all utilize to some degree and in our own combination's, but I believe yours is the clearest synopsis and explanation I have heard here to date. Very helpful !  -  Al

You're welcome!   :)

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Josh T.
meatballrocketry.com
TC Pro 18.2 & Platinum 2016