position expression

Question

Hello,

I want to animate the position of a pistion by two ways-

1- the rotation value of other elements in the composition

2-I also want to make that move up and down.

I used one expression control(angle) for rotation that controls the rotation value of all cogs in the animation.

I also pick whipped piston's position with that so can maintain the rythm with the rotations. But the probelm is I no way can make that pistion stop at certain point. because the position of the pistion is already taken/controlled by expression control angle.

Is there any way where I can maintain the speed of rotation in the position properties of the piston and also can stop in at certain level in Y axis?

(What I did found no way, I erased the angle expression from pistion's position properties and later place keyframed manually and loopout that. (attached)).

Thank you.

Mylenium · Accepted Answer

It's certainly possible, but not as trivial as you may think. The T-bar would actually only stop the gear rack when it's in contact, so the width and inclination of the teeth matters just as much as their width. Your math for the position is wrong, anyway. The gear rack will move about 1/8th of the circumference of the gear because it's diameter * Pi, not a direct linear relationship. And here, too, the inclination, height and width of the gears matter to figure out the actual contact points and how far everything moves. Did I mention that of course your gears cannot rotatet in different directions? With so many factors at play indeed just anymating a cycle by hand and then looping it seems much more straightforward.

Mylenium

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