topic Re: Transitional Movement with a Joint in Fusion Design, Validate & Document Forum

Transitional Movement with a Joint

ShayaGhanbar — Mon, 26 Mar 2018 17:13:37 GMT

Hey guys,

I am trying to create a relationship between a pin and a curved slot. I would like the pin to following the curvature of the slot. This motion is possible in Inventor with a Transitional constrain.

I would really appreciate if you help me figure out how to achieve this in Fusion 360.

Thanks,

Re: Transitional Movement with a Joint

Anonymous — Mon, 26 Mar 2018 19:39:27 GMT

I don’t know what exactly you’re trying to do. But you can use contacts (enable) then give it a circular motion. This would work

Re: Transitional Movement with a Joint

TrippyLighting — Mon, 26 Mar 2018 19:44:35 GMT

@ShayaGhanbar is the slot circular ? If so, you can simply create a revolute joint between the cylinder and the center of the slot curve.

Re: Transitional Movement with a Joint

ShayaGhanbar — Tue, 27 Mar 2018 15:44:21 GMT

@TrippyLighting the Revolute joint on the centre of the circle is a pretty smart work around! The only issue is that it only works if the pin transitions in circular path. I still think that Fusion need a type of joint to address this issue.

Here is what I am looking for that is done in Inventor:

https://www.youtube.com/watch?v=QKezL2zSvKU

Thanks for the help!

Re: Transitional Movement with a Joint

ShayaGhanbar — Tue, 27 Mar 2018 15:45:17 GMT

Here is what I am looking for that is done in Inventor:

https://www.youtube.com/watch?v=QKezL2zSvKU

Thanks for the help!

Re: Transitional Movement with a Joint

ShayaGhanbar — Tue, 27 Mar 2018 15:47:04 GMT

@Anonymous here is what I am looking for:

https://www.youtube.com/watch?v=QKezL2zSvKU

Do you think that this is possible with contacts?

Thanks!

Re: Transitional Movement with a Joint

TrippyLighting — Tue, 27 Mar 2018 15:55:49 GMT

Very much to my dismay the joint type you are looking for does not exist in Fusion 360.

There are 4 or 5 joint types that Fusion 360 is missing that really would make that area complete. We've been asking for some of these for several years now, but the development on the joint system seems to have come to a stop. Bugs do get fixed ( very slowly ) but there des not seem to be any development going on in terms of these new joint types. A joint that would follow an arbitrary path would work perfectly for this situation.

I personally find the joints in Fusion 360 very enjoyable to work with and also find them a very strong concept refreshingly different from the usual 3-geometric-mates paradigm in most other CAD systems.

Do not use contact sets except in the simplest of designs. They are a big ... let me rephrase e that ... B.I.G performance hog and often interfere with other joints in the design.

Re: Transitional Movement with a Joint

chrisplyler — Tue, 27 Mar 2018 19:12:04 GMT

Autodesk seems to get a product far enough along to garner buy-in from a large enough market, and then lay-off most everyone involved and only keep like a single, lonely, part-time development guy on it for the next decade. And as far as I can tell his job is 95% just to think up plausible sounding excuses, write them on napkins in the brake room, wad them up and leave them behind furniture around Autodesk headquarters. This careful business strategy is how they achieve the 1/100 odds that a call center employee will know what you're talking about when you need support.

Re: Transitional Movement with a Joint

ShayaGhanbar — Wed, 28 Mar 2018 17:18:21 GMT

Thanks for the help!

Re: Transitional Movement with a Joint

beresfordromeo — Fri, 30 Mar 2018 19:32:33 GMT

@ShayaGhanbarwrote:
@Anonymous here is what I am looking for:

https://www.youtube.com/watch?v=QKezL2zSvKU

Do you think that this is possible with contacts?

Thanks!

Hi There

I can't say as I can offer anything particularly helpful to this but I do have an observation and it would be interesting if anyone else has an opinion on this.

I came to Fusion as a Sketchup user (blasphemy probably). Sketchup had an old user built joints plug in called SketchyPhysics which was later updated (brilliantly in my opinion) by another user called AntonSynstria and renamed MSPhysics. What MSPhysics lacked in comparison to Fusion's joints (polished, professional implementation etc) it made up for in what I can only describe as analysis tools. It is hard to describe but basically you were able in MS Physics to see the geometry behind the joint plug in, this make sense in relation to Fusions contact sets because you could see the geometry that the contact was calculating a reaction to.

This is really hard to describe to but I think it may be relevant and worth documenting for someone using contacts sets in Fusion. What MSPhysics would do is calculate the 'bounding box' of the contacting geometries and attempt to resolve their reactions using physical rules. So for instance if I had a spur gear on a gear rack and I created the gear or rack bodies as a single entity with n number of teeth then the plug in would do its best to resolve this as a geometry. Since the software needed to constantly recalculate this the simulation would soon fail because it was just unable to resolve the physical interactions of two complex shapes in real time. However if I created the gear and rack by creating each tooth as an individual body (ie create one tooth and make an array of n number of them) then the simulation would work no problem because the geometry of the tooth made sense to the plug in. I was able to work this out because the plug in had an option to turn on the plug-in's view of the geometry.

I don't know if the above makes sense but I have noticed that I can get contact sets work fairly well in Fusion by breaking up the geometry into distinct bodies (more accurately components), that 'make sense' to the software. In your example above I guess that would mean breaking up the pin slot body (component) into two. One would be a grounded rectangular block with a flat face on which the pin would have a planar joint. The other would be the pin slot component which would be a rigid group with the rectangular block. If you then create a contact set between this and the pin component then the pin component will move in the pin slot as you would expect. It

In my case this works with no issue and does not load the CPU. I think that this is because the two geometries are separate and it is easy for Fusion to work out the needed simulation. If the pin slot body were one component then perhaps this would be different. I can't really say if I am talking nonsense here because unlike MSPhysics I don't have the visual representation of the simulated geometry to see what is happening but I can say that I have had some degree of success making unsuccessful contacts sets work with this method.

What would be great is if someone who knew how contact sets make their simulations was able to help us to clarify this or even better if they were able to look at MSPhysics and see the advantages of that approach.

So an indirect answer to your question is (in my opinion) yes this would work with contact sets but possibly only because I have no idea what I am talking about.

Re: Transitional Movement with a Joint

TheCADWhisperer — Fri, 30 Mar 2018 21:02:21 GMT

@chrisplylerwrote:
Autodesk seems to get a product far enough.... think up plausible sounding excuses....

No need for excuses - simply upgrade to the top tier solution (Autodesk Inventor Professional) where the development has already been done and the price of entry can cover the sunk development costs (and perhaps with enough left over to subsidize R&D on future CAD product(s)).

Re: Transitional Movement with a Joint

chrisplyler — Sat, 31 Mar 2018 00:35:48 GMT

@TheCADWhispererwrote:

No need for excuses - simply upgrade to the top tier solution (Autodesk Inventor Professional) where the development has already been done and the price of entry can cover the sunk development costs (and perhaps with enough left over to subsidize R&D on future CAD product(s)).

In order for that to be an effective solution to the excuse making, all Fusion users would have to "upgrade" to Inventor, because if there is one left, there is still somebody left to make excuses to. And if they ALL use Inventor instead, the business case for creating Fusion in the first place was terribly flawed.

What should Revit users upgrade to?

Re: Transitional Movement with a Joint

TheCADWhisperer — Sat, 31 Mar 2018 14:00:32 GMT

@chrisplylerwrote:

....all Fusion users would have to "upgrade" to Inventor,

Not all Fusion users need a full-featured MCAD program.

Not all Inventor users need Inventor Professional, some might only need the Inventor LT functionality.

There is a long history in the MCAD market of having entry level products and additional feature level products.

Actually, there is a long history in nearly all markets of having multi-tier level products so that the user is not paying for more than they need, but can upgrade when they can justify a higher tier product. Economics 101.

I don't know anything about Revit, but a quick search revealed that it looks like there are several Revit Products.

Re: Transitional Movement with a Joint

chrisplyler — Sun, 01 Apr 2018 23:39:06 GMT

Sooooo... excuses are still needed.

Re: Transitional Movement with a Joint

Anonymous — Mon, 02 Apr 2018 06:37:46 GMT

As far as I can judge, no CAD-vendor is really cheating. In most cases, you can download test versions - if you are in doubt. And you find a lot of information in the web.

If John Doe (individual or company) chooses to use/buy a product (any product), it´s his resposibility to evaluate the most efficient solution for him.

Wrong solution/choice?

Then blame John Doe.