How difficult would it be to......?

kees_bijker

Imagine you have a certain part with a finger style profile. This part is sliding up and meets another part.

How difficult would it be to create a series of restrictions or mates, so that second part is resting in place, maybe in some holder, until the first part meets it in its upward motion and it then it moves with this first part in the upwards direction?

Secondly, imagine a third part which is also in the holder, which is also taken up by the first part but in an unstable position resting in the fingers and against the second part. Now as they move up, the position relative to each other changes and the third part drops into the second part while both still move upwards.

For me this is pure magic and it would represent difficulty level max. But for those here who actively use the simulation tools, and maybe feature script, is this even possible in onshape?

jan_bouwman

It depends on what you mean by ‘simulation’.

If you mean that Onshape will calculate all movements based on physical properties of the model, external forces like gravity, wind etc., detection of collisions, impacts, scattering and all of that, as far as I know, Onshape can not do that (yet). 

However, if you know (or guess) what the final movements are and how they look like, you can make an animation of the parts that move.

Of course, when you change the properties of the model afterwards, the animations will not adapt accordingly. You will have to do that manually.

For another thread I made a short video on what can be achieved with animation.

I will add the link here as well and I am happy to answer any questions you may have on the subject.

https://youtu.be/Llsd4rxHDV8?si=8MzuwKggTRR8ylBE

kees_bijker

jan_bouwman said:

It depends on what you mean by ‘simulation’.

If you mean that Onshape will calculate all movements based on physical properties of the model, external forces like gravity, wind etc., detection of collisions, impacts, scattering and all of that, as far as I know, Onshape can not do that (yet). 

However, if you know (or guess) what the final movements are and how they look like, you can make an animation of the parts that move.

Of course, when you change the properties of the model afterwards, the animations will not adapt accordingly. You will have to do that manually.

For another thread I made a short video on what can be achieved with animation.

I will add the link here as well and I am happy to answer any questions you may have on the subject.

https://youtu.be/Llsd4rxHDV8?si=8MzuwKggTRR8ylBE

Natuurlijk een wind molen voor een nederlands voorbeeld :-) Moest er wel om lachen als nederlandse emigrant.

Absolutely fantastic video and I think the hatch doors opening when the bag hits them, and they even move according to the shape of the bag is actually pretty close to what I was looking for tbh.

A real simulation was a bit far reached, since this is not in the package I use anyway, but this example where you animate the movements and other objects are responding to this movement is really nice.

How do you link the hatch door movements to the bag? Some tangent mate while the movement is limited to the closed position maybe?

Interesting to say the least.

jan_bouwman

Natuurlijk een wind molen voor een nederlands voorbeeld :-) Moest er wel om lachen als nederlandse emigrant.

Haha, volgende keer laat ik een paar klompen zien als voorbeeld van mijn vaardigheden met de Loft-tool.

(Haha, next time I will show you wooden shoes (Dutch clogs) as an example of my lofting skils  )

How do you link the hatch door movements to the bag? Some tangent mate while the movement is limited to the closed position maybe?

No… the hatches are driven by the timeline, not by the bag.
so no mates between hatch and bag. When I leave out the bag completely, the hatches move exactly the same.
The making of the timeline however was a tedious job: for every step I measured the angle of the hatch when it touches the bag and adapted the timeline accordingly.
This creates a ‘rippled’ timeline.
I hope this helps. This method requires a bit of ‘inside out’ thinking. Or is this a too Dutch expression 

Here is the series of timelines used for hoisting the bag.
I think you can find the timelines for the movement of the hatches. 

jan_bouwman

How do you link the hatch door movements to the bag? Some tangent mate while the movement is limited to the closed position maybe?

I’ve been thinking… in a way you are right! Although the actual shape of the bag is not used directly, the timeline does represent the shape of the bag in a certain way.
And the shape of the timeline is followed by a pointer, indeed with a tangent mate.
The vertical movement of the pointer is then transferred to the revolute mate of the hatch door by a Rack & Pinion relation.
The limits of the mates are not used. However, limits are implied by the amplitude of the timeline.
so…

Animation through a timeline makes the animation more generic: you do not have to mate the movable objects directly. And it has some other advantages.

Interesting…

kees_bijker

jan_bouwman said:

How do you link the hatch door movements to the bag? Some tangent mate while the movement is limited to the closed position maybe?

I’ve been thinking… in a way you are right! Although the actual shape of the bag is not used directly, the timeline does represent the shape of the bag in a certain way.
And the shape of the timeline is followed by a pointer, indeed with a tangent mate.
The vertical movement of the pointer is then transferred to the revolute mate of the hatch door by a Rack & Pinion relation.
The limits of the mates are not used. However, limits are implied by the amplitude of the timeline.
so…

Animation through a timeline makes the animation more generic: you do not have to mate the movable objects directly. And it has some other advantages.

Interesting…

That timeline is an interesting thing, not used that before, will look into it even if just for fun and out of interest.

kees_bijker

jan_bouwman said:

How do you link the hatch door movements to the bag? Some tangent mate while the movement is limited to the closed position maybe?

I’ve been thinking… in a way you are right! Although the actual shape of the bag is not used directly, the timeline does represent the shape of the bag in a certain way.
And the shape of the timeline is followed by a pointer, indeed with a tangent mate.
The vertical movement of the pointer is then transferred to the revolute mate of the hatch door by a Rack & Pinion relation.
The limits of the mates are not used. However, limits are implied by the amplitude of the timeline.
so…

Animation through a timeline makes the animation more generic: you do not have to mate the movable objects directly. And it has some other advantages.

Interesting…

Hi Jan, it has been a while and I have been looking at that windmill many times. I also have found another animation with timelines and copied it to play with it, but it isn't completely clear. I tried looking in the edu center but I cannot find anything on this subject.

I did kind of get something out of it, but not perfect yet, have a look please and comment if you could.

https://cad.onshape.com/documents/dffac3f3be023381141e6569/w/8a3311ee176f6ffaf289ebee/e/84589491d0c91b5e57aca8c3

Do you happen to know of a course specifically on these timeline driven movements? That would help me a lot since Onshape's way of building the tutorials is perfect for me.

Kind regards in advance.

jan_bouwman

Hi Kees.

The Timeline method is invented by John McClary and he left us with two documents that show and explain his solution:

https://forum.onshape.com/discussion/10484/rubiks-cube-mate-animation

and

https://forum.onshape.com/discussion/18681/animation

I did not find any other tutorials.

Recently however I made a sample document about the animation of the millstone as seen in my YouTube video.

The document contains a PDF with elaborate explanations on the process of designing the timelines.

May be this helps a bit.

https://cad.onshape.com/documents/e36a4b13e729607a599eb3ed/w/3ad27495781ed00c4b08f4f3/e/c55bddc4a99f3ec5f25bf683

Then, I studied your document.

I see two mates that are to be moved, i.e. the Finger Rotation and the Lifter. They each have a Timeline.

However, I miss one important timeline: the one that rules them all!

The animations must be driven by a third timeline: timeline Zero. This is a completely straight timeline at level zero.

The pointer on this timeline must be connected by a horizontal Slider Mate and it is this Mate that must be animated.

All other pointers must be connected (by vertical sliders) to this Zero pointer. This makes them move together in horizontal direction and the (varying) vertical distance between one pointer and pointerZero is the measure for the relations.

The pointers 3 and 4 are obsolete as far as I can see.

A bit hard to explain in a short post, but you can read about it in my document.

In the mean time I will try to make a working animation of your construction in a different document, but this will take some time.

kees_bijker

Hi Jan, nice to hear from you. I will check your documents out for sure but just wanted to say that although mine is not having that zero timeline, it still works if you grab the time lines and move them from side to side.

Maybe I did it wrong and you are not supposed to do it manually 😁 But it does work in some sort of a fashion. It was enough for me to see that it would work in real as well.

Also the pointers 3 and 4 are the placeholders of the pointers that follow the tangent. They are attached with sliders and the tangent moves them up and down.

Looking forward to hearing more of what you said and reading, get on to that right now.

Thanks and kind regards.

P.S. I reckon I found the windmill you used in original shape. Was it moved some time ago and rebuild?

https://nl.wikipedia.org/wiki/De_Kersenboom

jan_bouwman

Hi Kees

I notice that the link is no link… I hope copy/paste will work.

OK, dragging the timelines does work indeed. But I never do that 😉.

And for the windmill you found: yes that’s the one!

Somewhere in the nineties it is moved from one side of the river to the other.