Floating model

[tspco]

I am probably wasting my time here again. I have a model that will use a pin that runs in a slot on a floor, well it is supposed to. When I start the animation the model floats up until the bottom on the pin is flush with the X-Y plane, then the wheels don't touch, and the model doesn't move. Ideas?
I tried making the wheels "taller", and the pin longer, the model now floats up further to make the pin flush, with the X-Y.

[Jim]

SketchyPhysics generalizes the shape of objects to make calculations quicker. It doesn't try to calculate every single vertex that defines a shape, but rather uses a simplified boundingbox to do the collision detection. There are various Shape options you can choose, and the one you likely want is the Convex Hull shape. But I am not familiar enough with SP to know the best way to construct or define the track.

[DanYHKim]

There may be some trick about how you connect the pin to the rest of your model that is relevant. I can't remember exactly how it's done, though. The idea is that if you make your objects as regular SketchUp objects, then select them all and group them, their collision geometry will be generalized, as mentioned before. That is, SP will just envelope the entire group in a single invisible rectangle that will define its physical boundaries.

You may want to make your main body as one group, and set its characteristics as "nocollision", then make a second group, consisting of your pin. Now group both of these together. The two groups may then retain their original collision boundaries.

I'll do a few experiments and take notes, then post them here. It's a common problem, and I am tired of having to figure it out from scratch every time, so having it written out would be good for me, too.