7 Replies Latest reply on Sep 16, 2016 12:54 PM by Dennis Dohogne

# Advanced mate - point moves inside a closed curve (Area mate)

Hi,

I'm trying to figure out how to do an advanced mate which is doing the following - a point from  Part1 to stay INSIDE a closed curve defined in Sketch on Part2. I would call it Area mate (point belongs to the area surrounded by closed curve).

There is advanced mate where it's possible the point to follow a path / curve but I can't see a mate where the point stays inside the closed curve (belongs to the area surrounded by the curve). Ideally it should be - a point to belong to the area surrounded by closed 3D surface - this will bring the ultimate freedom.

Why I need such advanced mate? Imagine a cylinder which has a big gap to the surrounding walls and can rotate and move in XY (limited in Z direction). Without such advanced mate I can't move freely the detail inside the chamber. Well, one patch is to use Move XYZ command and chose Collision detection but in my case this is not an option.

For some particular shapes like circle it's possible with big efforts to achieve such behavior with the existing mates, the question is what is the solution for any area shape.

Thank you

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

I don't believe SW has a mate like that. The closest I can think of is the slot mate.

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

Here is what I would try - If you make the "Area" a concave shape using the dome feature and then create a small ball part and mate it tangent to the plan face area as one mate - then I think you would need a distant mate from the center of the ball to another point in the assembly, as you don't want the ball to pop out of the domed area...

Then the ball would travel any where in the "Area" so the center is low and the edges would be high, so as the ball moves up it will crash into the distant mate and should force it to stay within the Area.

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

See the attached Peter - there still is a chance it could jump out, but I'm thinking adding other distant mates may box it in more

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

Thank you, I like the idea with the ball, if we spend more time it may really work. It's clumsy (compared to just adding one mate) but should works.

BTW, from the area mate could be derived almost all available SW mates. It's just pure spatial restriction - if the point is inside the area - movement was allowed, if outside - disabled.

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

BTW, in the Concave.zip solution the base plate should be extended beyond end of the curve - if trying hard and moving fast the ball may appear on the other side.

Still not clear how the limit in Z plus the curvature will affect the end trajectory of the ball - it's technically hard to get precise boundary path without doing a lot of calculations.

But the idea is kind of working to limit the movement inside area.

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

This was only a sample for you to achieve your ultimate goal so you can make additional changes in the Z height - but the issue with limit mates and tangent mates in SW - sometimes they jump to the other side of where you want it..

• ###### Re: Advanced mate - point moves inside a closed curve (Area mate)

The "jumping" John Stoltzfus refers to comes from the lag in computing the compliance with the flexible constraints.  Every time a component is allowed to move SWX has to calculate where it is with respect to the limitations placed on it.  Fixed limits are treated more like states, but movable mates require much more from the software.  As a result we can have a limit mate, but by moving something too fast it can jump its boundary, giving unwanted results.  This is easily seen with a tangent mate that flips; the part will still be tangent, but not on the side it was.  Same thing with limit mates.  I think I've even seen this with a gear mate.

I don't know that there is anything that can be done about it, but by being aware we a) aren't so surprised, and b) can take measures to deal with it.  Sometimes I create mates (and name them) that put things into their starting position then suppress them and let the flexible mates operate within their limits, but this time I might move things more slowly/carefully.