⚠️How to Simulate Assembly Rail Collisions

MichaelPascoe

There's probably a tech tip or post on this, but I thought I would share anyways.

You can simulate collisions on a rail with dynamic limits by:

Linear Rail

• Have each rail object start at the end of the next rail object.
• Limit their slider mates to a slide min of 0.
• Place one parallel (Or another slider?) mate at the end of the last rail object to the end of the rail with a min or max z limit (it depends on the direction of the mates).

https://cad.onshape.com/documents/6994e915ad627194a0adb342/w/3058edd611547121a3d93ba9/e/4e6b764ef825d94c54c5a1ba?r…

Alternatively, instead of a min slider limit where they all reference each other, you could probably have 2 parallel mates per end of a rail object, but this would take more time to set up.

MichaelPascoe

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Circular Rail

• Have each rail object start at the end of the next rail object via a rotated mate connector from the original part studio of the bracket.
• Limit the revolute mate to a min rotation of 0 for each mate.
• Place an additional revolute mate between the last bracket and the first one, and give it a limit of 360 deg.

Derek_Van_Allen_BD

What about a straight into a curve? I wanna simulate my garage doors

MichaelPascoe

@Derek_Van_Allen_BD For a garage doors, you won't need collision detection, just a chain of revolute mates and tangent mates.
I learned this technique from @NeilCooke I believe.

Animate Garage Door

• In a part studio, create a single edge path by using the Fit spline tool set to Edges. This will let you create one continuous path.
  Make sure the top edge extends well beyond the rail so that the helper parts have something to travel on.
• In the assembly, use parallel mate to lock the first door panel to the rail.
• Use the tangent mate to make one corner of the panel tangent to the continuous path.
• Add the next panel to the previous one using a revolute, then tangent mate the loose end to the path.
• Once you are at the top, use helper surfaces (Pushers) as if they were more panels until you get to the flat portion of rail. The reason for this is because Onshape doesn't currently allow you to animate the tangent mate. This way, you can push the tangent object with a slider mate that is animated.
• Add a slider mate to the final pusher and set limits 0 to 10ft or however large your garage is.
  Here is where you could add the collision technique if you want, but not really required since I know it's ~10ft.
• Right click the slider mate → Animate.

https://cad.onshape.com/documents/62fe036f7adf211619a6b478/w/9616e65987871ef989e3f83c/e/82402961e4bba1…