Please explain why this is over constrained.
- Thread starter cclark440
- Start date
I cannot explain, but it may have to do with the problem discussed last year:
viewtopic.php?f=10&t=11372
but this has not worked for me ... :evil:
viewtopic.php?f=10&t=11372
support said:
but this has not worked for me ... :evil:
This is very frustrating.
I noticed after upgrading to one of the past version, (V10 or V11 don't remember which), that the assembly constraint behavior changed.
It no longer allowed me to apply an orientation constraint after applying a mating constraint in certain situations. I know that it worked in previous versions because I had been doing it that way for years.
I have contacted support to open an case.
I noticed after upgrading to one of the past version, (V10 or V11 don't remember which), that the assembly constraint behavior changed.
It no longer allowed me to apply an orientation constraint after applying a mating constraint in certain situations. I know that it worked in previous versions because I had been doing it that way for years.
I have contacted support to open an case.
In principle, this component should not be over constrained, but I suspect this is because Alibre does not interpret the axis and the plane as being orthogonal. I think that Alibre maintains an 'orthogonal' flag between certain features such as planes, faces, holes etc, which by design are orthogonal. Features that are not orthogonal by design, but happen to end up at 90 degrees may not be assigned this 'orthogonal' flag.
In this example, Plane<3> may not have been set as orthogonal to Axis<2> even though they are. The constraint system may be looking at orthogonality and not being at 90 degrees. The constraint system says they are not orthogonal and throws the error.
I have seen this before and this is the conclusion I have come to. I think the trick is to define a point at the centre of the forward face (centre of the circular edge) and then mate the point with Plane<3>. The component is then correctly positioned along its axis, and the constraint mechanism is satisfied.
In this example, Plane<3> may not have been set as orthogonal to Axis<2> even though they are. The constraint system may be looking at orthogonality and not being at 90 degrees. The constraint system says they are not orthogonal and throws the error.
I have seen this before and this is the conclusion I have come to. I think the trick is to define a point at the centre of the forward face (centre of the circular edge) and then mate the point with Plane<3>. The component is then correctly positioned along its axis, and the constraint mechanism is satisfied.
setup B overconstrained ?
referring to the file setup B:
Given constraint 9 and assuming that face 15 is perpendicular to face 27, I think that the edges 56 and 46 cannot both be in the YZ plane (just as face 27). They can both be (actually have to be, here comes the over-constraint) in plane 3. If you un-suppress all constraints you get the error message again.
Here is what I am thinking:
1. plane 1 is at an angle of 15 degrees to the XZ plane by definition
2. axis 2 lies in the intersection of Plane 1 and XY, therefore also has a defined angle towards XZ and YZ (!)
3. via face 15 and constraint 9, face 27 has to be perpendicular (see assumption above) to axis 2. Due to 1. it can therefore not lie in YZ.
Can i ask a question? Why do you enter the constraints twice? What does one accomplish by that?
benji
referring to the file setup B:
Given constraint 9 and assuming that face 15 is perpendicular to face 27, I think that the edges 56 and 46 cannot both be in the YZ plane (just as face 27). They can both be (actually have to be, here comes the over-constraint) in plane 3. If you un-suppress all constraints you get the error message again.
Here is what I am thinking:
1. plane 1 is at an angle of 15 degrees to the XZ plane by definition
2. axis 2 lies in the intersection of Plane 1 and XY, therefore also has a defined angle towards XZ and YZ (!)
3. via face 15 and constraint 9, face 27 has to be perpendicular (see assumption above) to axis 2. Due to 1. it can therefore not lie in YZ.
Can i ask a question? Why do you enter the constraints twice? What does one accomplish by that?
benji
Ok, after reading all of your feed back I have resolved the constraint issue.
What it took was Aligning Face 15 to Axis 2. This satisfied the primary angle on all of the 4 faces.
Then I created a point on face Face 27 where Axis 2 intersects.
I then mated Point 3 to the Origin.
I then orientated the EDGE where the face I wanted and face 27 intersect, to the ZX plane.
I created configs so that each face can orientate up. I really only need to do two, but I wanted to see if they all worked.
I still don't really understand why I had to use the edges and not the faces themselves for the orientation.
Anyway thanks for all of your feedback.
What it took was Aligning Face 15 to Axis 2. This satisfied the primary angle on all of the 4 faces.
Then I created a point on face Face 27 where Axis 2 intersects.
I then mated Point 3 to the Origin.
I then orientated the EDGE where the face I wanted and face 27 intersect, to the ZX plane.
I created configs so that each face can orientate up. I really only need to do two, but I wanted to see if they all worked.
I still don't really understand why I had to use the edges and not the faces themselves for the orientation.
Anyway thanks for all of your feedback.
my solution
Based now on the original file posted, here is what I came up with, I hope I caught all your ideas:
align 3 is your constraint and defines the orientation of the piece in the coordinate system
align 8 defines the position of the piece along axis 2. To my mind one cannot take a plane from the coordinate system as a reference here because the angle between face 27 and any plane in the coordinate system is already defined by the "detour" described in my previous comment.
angle 1 defines the rotation of the piece around axis 2. You can play around and change the angle in the constraint.
hope it works for you. Now I only have to upload the right file. :?
Benji
Based now on the original file posted, here is what I came up with, I hope I caught all your ideas:
align 3 is your constraint and defines the orientation of the piece in the coordinate system
align 8 defines the position of the piece along axis 2. To my mind one cannot take a plane from the coordinate system as a reference here because the angle between face 27 and any plane in the coordinate system is already defined by the "detour" described in my previous comment.
angle 1 defines the rotation of the piece around axis 2. You can play around and change the angle in the constraint.
hope it works for you. Now I only have to upload the right file. :?
Benji