Assembly3 - roller in curved slot

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p19a
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Assembly3 - roller in curved slot

Post by p19a »

Hi, I'm new to FreeCAD. I'm recreating a linkage but having trouble constraining these two parts together. I need Lever2 to have Rz free and translation within the slot. I can get the right movement on the full circle using PlaneAlignment and PointsOnCircle, but I can't find a way to limit movement to the ends of the slot.
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bambuko
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Re: Assembly3 - roller in curved slot

Post by bambuko »

p19a wrote: Sun Mar 19, 2023 2:40 pm ...I need Lever2 to have Rz free and translation within the slot...
What is Rz ?
and - I presume you are using master branch of FreeCAD?
I am using Link branch and Assembly3
you can also download ... and try it here
excellent Assembly3 tutorials here
p19a
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Re: Assembly3 - roller in curved slot

Post by p19a »

Rotation around Z axis. So Lever2 should rotate freely as long as the circular pad stays within the slot. I'm using 0.20.2.
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bambuko
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Re: Assembly3 - roller in curved slot

Post by bambuko »

Thank you for the translation :lol:
I was guessing this was the case, but better ask....
I am using Link branch and Assembly3
you can also download ... and try it here
excellent Assembly3 tutorials here
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bambuko
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Re: Assembly3 - roller in curved slot

Post by bambuko »

Do I understand that lever1 is fixed rigidly at the two points I shown with red circles?
BTW "locking" lever1 in assembly 3 locks it in relation to other parts - it doesn't fix it in space
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I am using Link branch and Assembly3
you can also download ... and try it here
excellent Assembly3 tutorials here
p19a
Posts: 3
Joined: Sun Mar 19, 2023 2:27 pm

Re: Assembly3 - roller in curved slot

Post by p19a »

This is all part of a much bigger mechanism with both levers shown attaching to more levers. I have most of that working. For this demo I simply 'locked' Lever1 to try and figure out the roller/slot constraints, as I understand it shouldn't matter when I work the solution into the main files.
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bambuko
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Re: Assembly3 - roller in curved slot

Post by bambuko »

I have modeled and animated similar assemblies (using limited slip eccentric),
but must admit that I never managed to model the slip.
So far I basically have an assembly with two different skeleton sketches one for each extremity of the slip (or slide in slot in your case)
and animate either case separately :?


I am quite interested in your model for this reason.
Without understanding what drives what in your model it is even more difficult.
Is it that lever1 is fixed (defining slot position) and something is rotating lever2 from one end of the slot to the other end?
I am using Link branch and Assembly3
you can also download ... and try it here
excellent Assembly3 tutorials here
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FBXL5
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Re: Assembly3 - roller in curved slot

Post by FBXL5 »

bambuko wrote: Mon Mar 20, 2023 9:58 am "locking" lever1 in assembly 3 locks it in relation to other parts - it doesn't fix it in space
The object is locked/fixed inside the Assembly container. If you move the container, you are right that the object moves through space as well. If you consider the Assembly container as fixed to the global CS then "locking" fixes the object in space.

As far as I know there are no limits to translations or rotations implemented yet. Such limits can be set within a controller app but only for a driven constraint.

A controller could drive the movement within the slot and another could drive the main movement, but then you need to synchronise both controllers. Maybe this could be achieve with expressions.
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