Hello
When I go to rotate a coordinate system relative to another (with the axial rotation tool when creating an axis system) in the part workshop, I currently encounter a small problem that seems to be recurring.
If I rotate with a Z axis and with the X ref axis, I can build my second coordinate system with a 20° angle rotation for example.
On the other hand, if I now rotate the Y axis and as the X ref axis, I encounter my problem, the second marker as input with an angle of 90°. I don't understand at all where this can come from.
By the way, in CATIA's help, it also seems that there is a typo because he gives the example of a rotation along the Y axis and an angle of 15° and he gives a figure with an angle of 90°+15°...
I have built a small file to test my problem (in copy) and that you can also test.
Do you have any ideas of how I can build this Y-axis rotation and as an X-ref axis?
Thank you in advance for your help.
rotationrepere.catpart
Hello
It's an anti-clockwise rotation with respect to a reference, if you orient the vertical rotation axis on the screen (whatever it is) and you play on your angle value you will see that Catia rotates counterclockwise.
If entering a negative value (-20°) sets you PB the only solution is to isolate the coordinate system, then constrain it (we use the compass to pre-orient it).
Hello Franck,
Thank you for your feedback.
There is more than just a 20° sign problem because the 20° angle you see in the case of rotation around the y-axis is not between two x1 and x2 axes but between an x1 and y2 axis. Which makes it a weird rotation. Here are some illustrations to better explain this behavior of CATIA:
Otherwise, thank you for your bypass. I didn't know that you could use these constraints in the Part workbench, so I use the constraints in the Assembly workbench instead.
On the other hand, I find it a bit weird that I can't do the rotations I want with this "axial rotation" tool. I would have liked (but maybe it's a dream) the rotations of my landmarks in a room via this tool without making gas plants for a simple rotation.
If you have any new ideas to make this axial rotation tool obey us better, I'm all for it.
Thank you for your help.
You can't tell CATIA puts me 20° between the X(1) and X(2) axis.
We can't tell him which axis of the coordinate system we are creating is used for the angular stress, we just choose the reference axis on the coordinate system on which we are relying.
In your case, to get figure N°3, you have to choose Z1 as a reference and you get 20° between Z1,Z2 and X1,X2
Great Franck. You solve my problem.
In fact, I now finally understand how this tool works.
When we take a direct coordinate system, the order of the axes is YZXYZXYZXYZXYZX ...
The axis of rotation that I've chosen is Y.
Next, we have two rotating vectors Z and X.
For the tool to work, you have to take the first of the rotating vectors to be Z and not X to stay on a direct trihedron!
One way to see it is also to draw what mechanics call the dials that we use when doing kinematics.
Thank you for your help.
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