part flipping 180 degrees when coincident mating

[sculpturetim]

Hi there,
i am trying to hang a tile made in solidworks onto a spline. I usually move the tile close to the position i want and then mate it with coincident mates, (mating a point on an underlying sketch to a spline) sometimes it will flip the part over to the opposite side that i want, sometimes i can undo the mate and reposition and it will work, sometimes not! any suggestions how and why this is happening and how to control it better?
Thanks
Tim

[matt]

use a parallel mate, or an angle or distance mate with a narrow range.

[SPerman]

Or better yet, generate other geometry to control this. Angles and parallels have a way of flipping in SW.

[sculpturetim]

Thanks for the replies matt and SPearman,
ive tried a parralell mate to the top face of tile but it didnt like to mate with spline, possibly because its a curved spline and a flat surface?

The angle of dangle of the tile is variable so im not sure an angled mate is possible( couldnt figure it out yet, will do more research)

Genereating more geometry to stop it flipping sounds like a good idea but I was not sure what i could do that would work, more sketches?

to give more detail, the model is an egg shaped steel cage that the wooden tiles are tied onto to cover and create a tiled surface.once i have hung the tiles on the steel frame i adjust the angle to sit comfortably on the layer below them, here is a picture of the whole sculpture in progress. Many thanks for your help.
Tim

[KevinC]

A point coincident to a spline (or anything else) is a gimble (gimbal?) situation.
All sorts of pivoting about the point and translation along the spline can occur without violating the mate.
Perhaps another mate or mate entities selection, as others have mentioned, may be required.

[sculpturetim]

Thanks for your replies Kevinc and Tootalltoby,
i could add a mate but not sure exactly the best way to do that, and i could add a reference plane in the centre, not sure what would be the best kind of mate to attach a reference plane to a spline and ideally still allow the tile to pivot at the spline...?

[Ben]

you could go into that splines and put 2 points that are dimensioned on that spline and then all you need is a 3rd point somewhere in space. are you using a 3d sketch?

i saw you manually align the tile to lay on top of the others. please for the love of god, either fully mate those tiles or fix them in place. from what i see, if you mess with that spline, its just going to totally ruin anything.

[SPerman]

I'm not sure how well this will work in the 3d environment you have going on, but this is what I would try.

Line C is coincident with the origin (or center of the circular pattern.)
The endpoint of line C falls on Spline B. It also falls on the midpoint of line B.
Line B is tangent to Spline A. Line B is perpendicular to line C.

The base of the tile is coincident with line B.
Add a point on the tile that will fall on the endpoint of line C.

Without testing I can't say this is foolproof, but I think this should be stable. If not, I would think about how to use planes as reference geometry. But my approach would be the same. Tangent to the spline, and perpendicular to that tangency.

[SPerman]

Cool project, by the way.

[IndianaDave]

This is an application where precision really isn't as important as appearance.
I would create the two points per tile on the splines, as shown above, and constrain the tile to those.
Then manually rotate the tile into position, and fix it in place.
No need to create tons of constraints.
That many constraints on that many tiles will cause your model to bog down and become very hard to work with.