How to animate two tangential components?

[ashes.man]

I have been trying to animate this linkage with no luck.  Each tangential joint works on its own, but when both enabled they sort of lock up.

Any advice appreciated.  Model attached.

[davebYYPCU]

Same here. I deleted the contact sets, and removed the Rest positions in the Joints, (tangency makes this redundant)

I can make either tangent relationship work, when the other one is suppressed.

Above my paygrade.

Might help.....

[TheCADWhisperer · Accepted solution]

@ashes.man 

First thing I would do is edit the design such that this interference does not occur on motion.

Try making this as a separate component so that you don't have two different Tangent Relationships on the same component.

[davebYYPCU]

So, you and the demo movie are saying Fusion will not do 2 Tangent Relationships on the same component - without a warning dialogue?

[ashes.man]

Thank you both for taking the time to have a look at this.  /after making the suggested changes, things are working as expected.  I have several more tangential joints to add to this mechanism yeet so will be interesting to see if I can get more working.  Shame you have to do odd workarounds and that animation does not work.

[ashes.man]

As a follow up, I finished the mechanism I was hoping to get working, and it sort of works.  If you drag the grey base, it will get the cam off center, then you can drag the cam around.  But if it gets back near center, it stops working.  Not sure if my PC just doesn't have the grunt to manage it, or if it is just a F360 limitation.  Be really nice if you could animate it though.

Also not sure how to ground the grey base.  Seems the red part always stays stationary.

Model attached

[TheCADWhisperer]

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@ashes.man wrote:

  Shame you have to do odd workarounds ....

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How would you manufacture a hemisphere on that planar face in the real world?

Wouldn't this actually be separate components in the real world?

[davebYYPCU]

The red component is Pined to Parent and can't move.

That means the grey base has to move. It would roll and slide where the cylindrical joint is.

When the cam is driven, the blue lever operates on the 2 spheres, pushing the grey base clockwise / anticlockwise, 

simultaneously the grey lever reciprocates the base front to back,

If you ground the base, then the red component (ungrounded) would take on the movements I described, correct?

As delivered this file is working with manually moving the grey lever.  The Animate relationship with Revolve for the cam is not working here either.

Might help...

[ashes.man]

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@TheCADWhisperer wrote:

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@ashes.man wrote:

  Shame you have to do odd workarounds ....

---

How would you manufacture a hemisphere on that planar face in the real world?

Wouldn't this actually be separate components in the real world?

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Any sort of additive manufacturing.  CNC milling from a solid billet.  Turn the spherical part on a lathe with a ball turner.   Lots of options.  But in practice I was intending on pressing a ball bearing into a steel block.   

There is no relationship between what is a component in the real world and in CAD.  That part may be made of two bits of metal, but once pressed together sold or bought as a single component.  It could be a complex part made of 100 sub components by a third party, but modelled as a single body as that is all they give you.

[ashes.man]

So, I put this concept in to a real design.  Unfortunately the tangential relationships don't want to play ball.  Three of the four of them are all working perfectly.  But where the roller runs on the cam, I cant seem to add a tangential relationship there.  I tried putting a cylinder around the cam so the roller was only contacting a single point on the cam rather than the entire face width, but that did not help.  Contact sets don't seem to work either.

Any ideas?

[TheCADWhisperer]

@ashes.man 

For a mechanism like this I would use Autodesk Inventor Professional - Dynamic Simulation Environment.

[ashes.man]

OK.  Thanks for the suggestion.  I am a hobbyist just playing with this stuff at home so don't have licensed versions of the professional products.   I just thought it would be nice to have it all working.

[davebYYPCU]

It does work as expected.

Animate Revolve 7, in this component, after you add the 4th Tangent Relationship, as explained below

Seems that Fusion could not set up that relationship, with the file as you had it, looks to me like it didn't like the original overlapping components, when overlapping the error is delivered, as you are aware.  I dragged the bearing off the cam, to give an airgap, (Capture this position) then the relationship is able to snap into position.  (At least for me) 

Normally you would Delete this Capture Position icon after a Joint is created / exists to override it, however deleting this one after the Relationship is working will error out again.

@jeff_strater is this expected behaviour?

Might help...

[ashes.man]

Thanks for the suggestion.  I did some playing with creating clearance between the relationships before making the tangential relationships.  The results were varied.   Sometimes it caused the relationship to work better, sometimes it fails completely and errors when trying to make the relationship.   I noticed that if I just animate the relationship between the cam and roller, it works fine, even if the roller starts at zero clearance.  But once you add other relationships, having clearance between the cam and roller improves the situation.

Seems like there is some room for improvement with this feature in the future.   I cant imagine how complex the math is to do this so can understand that it might not be perfect.  I think my design contains no conflicting motion that would cause "binding".

My current design sort of animates.  Sometimes it does a full revolution of the cam, other times it gets stuck.  I think it could be that the face of my cam is made of several parts now rather than one face all the way around.  Although that does not bother it when you just animate the cam/roller relationship.  Could also be that my PC does not have enough horsepower to animate nicely.  It is getting long in the tooth.  Could someone with a grunty machine please try it for me and see?

I would be stoked to see it animate properly though, so I could check clearances and gain some confidence, and also, just because its cool when it all moves!

[davebYYPCU]

My file animates the Joint Relationship, of Revolve 7 

It is normal for Fusion to do just one 360 revolution and then reset.

Is this what you see?

Might help....

[ashes.man]

Thanks for demonstrating that.  My one moves in jerks and fits, and eventually hangs up at the same point where your one hesitates.  I will give it a try on a better PC and see if maybe that is all I am up against.