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Hexagon pentagon assembly - failing constrains (by Luca)
Hi all,
I am trying to mate two hexagons and on pentagon on 1 vertex and 3 edges.
I know this mating is possible because of geometry reason and reverse modeling from other models. ( )
Here's my steps:
1) I place next to each other 2 figures (does not matter which one) and make On point constrain for one end of the common edge.
2) I try to mate the other point on the other end of same edge, but I get a "solved failure" msg.
Odd, I do not see why it should happen. They are 2 points on the same line.
3) I work around this issue by using a Parallel/Tangent constrain
4) When I place the third figure, I use again one On point constrain and one Parallel/Tangent.
5)Now I have one hexagon as "base" and the other two figures on two adjacent sides, free to rotate around the edge.
6)If I try mating the missing common edge/common point, I get a "solved failure" msg as well and basically I am not able to complete my task, even tough I am sure that is possible to achieve the shape.

What I am doing wrong with the constrains?
Is it a limit of the software?

As a side request, is it possible to have a simple planar surface without thickness?

Thanks in advance.
Fri Mar 18 2016, 07:37:24, download attachment hexpen.slvs
(no subject) (by User1)
You post only assembly file, but it need parts, that you try include in assembly.
Give us next files too:
1) hex.slvs
2) pen.slvs

In next time, try zip all files, that you include in assembly.
Fri Mar 18 2016, 12:46:20
(no subject) (by Jonathan Westhues)
As User1 notes, we can't open the assembly without the parts too.

But, you seem to be overconstraining the parts. For example, two point-on-point constraints will always overconstrain, because they're either redundant (if the distances between the point pairs are equal) or inconsistent (otherwise). Take a look at the assembly tutorial for examples of sets of constraints that exactly constrain a part in an assembly.

whitequark et al. have a development version in which you can permit overconstraints if they're redundant but not inconsistent. If you don't want to think about how many degrees of freedom you're constraining, that might help.

Also note that groups are solved in order, with geometry in earlier groups locked down by the time a later group is solved. In your step 6, it looks like you're constraining in a way that would require two parts to move, which won't work.

My suggestion would be to sketch the shapes as wireframe, in a single "sketch in 3d" group. That way everything is solved simultaneously. If desired, you can constrain solid parts against the wireframe later.
Fri Mar 18 2016, 14:15:57
(no subject) (by Jonathan Westhues)
And an example is attached. One hexagon is sketched in g002, in the xy plane. In g003, we create two free workplanes (Sketch -> Workplane), one with another hexagon and another with a pentagon. We then constrain the shapes against each other (taking care not to overconstrain them; note the use of point-on-line constraints). Since both free shapes are in a single group, that works as expected.
Fri Mar 18 2016, 20:06:00, download attachment trunc-icos.slvs
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