Revolute Joint Conflicts

[Anonymous]

Joint ConflictBefore attempting to join

Hey guys I'm a grade nine student and for my assignment I'm building a wooden toy digger. I have everything else working but when I try to join the moving bar across it comes up with a joint conflict and even though the joint at the other end is a revolute joint. I'm not sure how much of what I'm saying is making sense so I'll attach a few screenshots or I'll try to attach the file (if I can work out how to).

[davebYYPCU]

Without your file to check things, 

I can only say that the two joints on left have to match the spacing of the top right side joints, 

In other words the two long rails have to be parallel at all times, for that system to work the way I think you want it to.

Could be wrong....

[Anonymous]

Hey davebYYPCU,

Whilst your suggestion would have helped the mechanical side of things later it's still coming up with a joint conflict even though it's parallel. It could be the fact that the joint isn't on an angle that directly leads to the joint I'm trying to connect to it but I tried to work the maths of the angles out in my head and my guess was quite wrong.

I've seen on other discussions that people have been able to upload their projects to these forums and I think it could help but I'm sure how to do that if you could tell me how.

[TrippyLighting]

This article describes several ways of how to share a design.

If you missed how to create a screencast. The first three tips here should be a must for every new Fusion 360 user.

[davebYYPCU]

Sure, under the File menu, select Export, will save the file to the hard drive, select a place to put it.

Then in a new message here, there is a box for attachments below the message window, browse and select the exported file.

However, the conflicts are a catch 22, because the top rail is not already parallel, is making hard work for you, (calcs for angles you mentioned)

delete the Joint causing the conflict, likely to be the last one,  so that you have it stable again.

I would remove the Joint limits as well until later, (lower left joints) leave it to free wheel until it all comes together.

Might help....

[Anonymous · Accepted solution]

So I was talking to my teacher and he was as stumped as me so he found this video and the guy in the video used cylindrical joints instead of revolute joints I presume to account for any minor changes. So I replaced all of the revolute joints with cylindrical joints and the joint conflict was resolved.

Here is the link:

https://www.youtube.com/watch?v=LN4bvjfxQ4c

[TrippyLighting]

I did not have time to look at your assembly in detail but that was the first though that I had, that your design is simply over constrained by too many revolute joints that don't all line up.

Using realistic joints just as you would in reality is a good idea.

Now, replacing all revolute joints with cylindrical joints obviously also is not a good idea as that may under constrain your assembly 😉

However, if you designed everything to nominal dimensions and everything "should" line up but somehow you still get errors when using revolute joints, that's a good reason to look if all your sketches are constrained and dimensioned properly. Based on my experience looking at hundreds of user files, yhat alone accounts for the majority of reasons why designs "lock up".