Animating eccentric gear

[etfrench]

Here's a screencast of the three related joints:

Is it possible to get the large gear and slider to follow the eccentric gear?

[Beyondforce]

May I ask, why did you choose Direct Modeling?

Ben.

[etfrench]

Here's a simplified model.  It's able to move one direction, but the contact set gets broken.

p.s. I use Direct Modeling because I don't like components deleting themselves when a sketch is modified.  Components also jump to their origins at odd times. 

[etfrench]

Screencast was deleted from previous post by forum software during the edit.

[Beyondforce]

That's not a good reason for using a Direct Modeling.

1. "components deleting themselves when a sketch is modified", what do you mean? Could you make a screencast? I never heard about it!

2. "Components also jump to their origins at odd times.", This video will help you to understand, how and when to use the move command: https://www.youtube.com/watch?v=9DiwbQMQXNQ

In Top Down workflow, you are rarely need to move a component, because they whole idea is to build the component in the place it should be!

Ben.

[Beyondforce]

The large gear, needs a "Rest position", which is in your case the start position. This way it will follow the smaller gear.

[TrippyLighting]

Tere is nothing inherently wrong with using direct modeling, but it sounds like you are using it because you are missing some key concepts when modeling with the timeline.

Your assembly cannot work at the moment,  because a base requirement in assembly is that at least one component has to be grounded. In this case the pinion for the small gear is, but one of the rials for the sliding table should also be grounded.

In general, however, attempting to simulate toothed gears by using a contact set is not going to work in practice. Contact sets at the moment work only in simple cases with simple geometry.

A gear geometry with 150 teeth is too complicated to evaluate for contact sets.

For this kind of Cam motion you might be able to use a motion link between the small gear and the slider joint and another motion link between the small and the big gear.

[etfrench]

I'm sure you're correct when you say I'm missing some key concepts in the timeline mode 🙂  The direct modeling mode works the way I'm used to working and I haven't seen any overriding benefits in the timeline mode to make it worthwhile changing.

In the simplified model, I haven't been able to get the main gear to maintain contact with the pinion gear even with the rail and pin grounded.  If this can actually be made to work, then transfering it to real gears is just a matter of creating cylinders of the gears pitch diameter and turn off their visibility in the animation.

[Beyondforce]

Hi @etfrench,

Here you go, this might help. The gears are not turning 100% at the same time, but the Eccentric effect is working really good.

This of it like the Train wheels. This will help to understand what I did.

I will make a video on my YouTube channel about how to make this model and the animation. But for now, you can just Reverse Engineer it.

For some reason, the screencast doesn't capture the animation nicely, but when you will animate it in your computer, it will work!

Cheers / Ben
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[etfrench]

That's a really good try, but the smaller gear is also moving vertically. 

I've been trying to get this to work using a cam instead of a gear, but no success yet.

[Beyondforce]

Vertically? Don't you mean Horizontally?

[etfrench]

Sorry, I misinterpreted the action of the gear.  It is moving correctly.

[Beyondforce]

OKay, so you want them both move horizontally or it is ok the way it work now?

[etfrench]

It's looking good the way it is.  Thanks for showing how to do this.

Now to move on the the hard ones 🙂

[Beyondforce]

It feels like you are testing me? 😉
I can make it work.

[etfrench]

---

@Beyondforce wrote:
It feels like you are testing me? 😉
I can make it work.

---

Tests are fun

Here's a video of what I'm trying to animate: https://www.youtube.com/watch?v=4XDIonkwTRo

The video only shows round gears, but having gears with 2 to 10 sides would be quite interesting.  I still need to determine what the parameters are for mating non concentric gears to concentric gears.

My design for a rose engine is nearly complete, but it would be nice to animate the different motions that are possible.  This would really help validate where each component is placed.

[Beyondforce]

Can you send me the file of the last image?

[etfrench]

Here's the file.

[Beyondforce]

Great, i'll get back to you.

[Beyondforce]

I didn't forget you. There are some issues with Revolute joint. It seems like a bug, but I'm waiting for it to be confirmed.