Driving joints of a foldable triangular structure with 2 legs

[Ceecis]

I am unable to fold this structure as intended. All the hinges are properly aligned. What is wrong with it and how can I fix it? Each hinge has a revolute joint. The ends are joined with a slider joint.

Do you think it would help if I created components with a sketch containing a single line, the ends of which would serve as joint origins for each half of the hinges, with only one joint being a revolute joint, rather than assembling the hinges together end to end for each leg?

[jhackney1972]

You need to attach your model so the Forum users can take a look.

 f you do not know how to attach your Fusion 360 model follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save as a F3D or F3Z file to your hard drive. Then use the Attachments section, of a forum post, to attach it.

[Drewpan]

Hi,

The first thing you need to do is export your design to an .fd3 file and upload it so we can have a proper look at it.

Just by looking at what is here, I would guess that your joints are not constrained so that they revolve all the way

around instead of a range. It isn't alignment that will be the problem here. DO NOT try to use contact sets.

Cheers

Andrew

[etfrench]

Does each individual Revolute joint work?  If so, try changing them to Cylindrical.

[Ceecis]

My bad. I had already exported the file with the intent to post it, but forgot to attach it. It has been attached to the original post.

[Ceecis]

When the slider joint at the end is not active, the individual revolute joints do work. Changing them to cylindrical joints leads the structure to be completely dislocated.

[Ceecis]

The joints are constrained to 180°.

[jhackney1972]

What is the purpose of the Slider Joint? 

[Ceecis]

So the ends stay aligned. This way I will only need to attach one of the hinges.

[jhackney1972]

A Slider Joint removes all degrees of freedom except one, along the axis of the slider joint.  You model will never work with this joint in place.  If you want the legs to move together, switch to Motion Links between corresponding joints.

[Ceecis]

Doesn't motion link work only with joints? How can I link the ends with motion link?

[Ceecis]

I found the issue. The angle on the elbows wasn't quite right.