# Thrust crank

Why doesn’t the Grab component work? What am I doing wrong? I would like to create a basic crank to which I can add solids.
Is it possible to apply constant rotation to the crank mechanism?

rotazione.3dm (66.2 KB)
manovellismo.gh (8.7 KB)

thanks

Il file .3dm è vuoto…

non è vuoto, il secondo livello è spento.

One line is out of plane (Z not 0) and completely constrained by anchor goal at both ends.
For the other line you used the curve as plane for the support goal…

Can you explain what you want to do?
An example video, maybe?

Is it correct?

crankshaft.gh (17.5 KB)

Making a crankshaft with just 3 points in total is to much “wobbling”, at the dead centres it almost bounce back, exactly like what would happens in real life having both crank and shaft made with springs.

To give it more inertia, used a polygon as a flywheel…

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Polygon…

No Polygon, circle.

faceted circle?

maybe

Can anyone be nice and explain the marked components to me? When to use them?

The Entwine component as in Riccardo’s definition can be useful as a way of organising the data going into the solver, so that it can be operated on further. When you explode the output of the regular solver, the data tree structure corresponds to the data tree that went into the GoalObjects input.
The ‘Show’ component lets you input geometry and have its points moved along with the particles in the simulation they coincide with.
For these small examples it doesn’t make much difference, but when you are making larger definitions it can be very useful to get specific ordered sets of lines/points/meshes after they have been moved by Kangaroo so you can build more geometry on them downstream.

Also - I notice you are still trying to use the rigid bodies in your first definition in this thread. As I said in your other thread about the pendulum - I think it’s usually better to avoid using the rigid body component where simple points and length goals will do - it makes things more complicated than needed.
For the crank you only need 3 points in the plane to completely define the motion - all the circles/solids etc you need can be positioned based on these.
The rigid body goal is only really needed for more complex out of plane mechanisms involving bodies with changing 3d orientations that cannot be simply defined relative to a line, such as this:

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1. created the crank mechanism with polylines,
2. created solid shaft (crank);
3. created solid connecting rod,
4. I associate two solids to the two lines of the polyline,

but the motor shaft seems to move and rotate with respect to another axis.
Why?

ps @DanielPiker can you explain why did you use the “orient” component?

With mesh:

manovellismo.gh (26.9 KB)

Hi - the geometry is not internalised, so I can’t see the file.

Orient is used to transform geometry from one plane to another.
In my example on the pendulum thread I created planes based on the lines so that the solids could be oriented to them.
To create the plane you need 2 vectors - here you’ll probably want to use the direction of the line, and the same vector rotated by 90 degrees in the plane of the motion.

Ok but in your code there is a problem with dot product, every 180deg vector change and the model became simmetric.

I don’t understand vector position and why you use Y axis.

Why this plane specific?

ok ok no problem,it s works

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