I'm having a really hard time transitioning from SolidWorks to Fusion with regard to joints and I'm hoping someone can help set me straight!
Per the image below, I have two rectangular components and I want to create a joint or (set of joints) so that the top piece can move freely on the bottom piece while the 3 corners of the top piece are touching the dotted lines.
I've watched the videos, read about joints, and I'm still stuck. Can anyone walk me through how you would accomplish this?
The motion you desire is mathematically impossible. You can have any two corners riding along the imaginary line (actually a fence component turned off) but you cannot have three. There is only one position where all three corners can be touching the fence but cannot be dynamic between three points. Model is attached.
Next time you post, be sure to include your model to first of all be more relevant to you plus save the time for a Forum user to create the model.
John Hackney, Retired
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I'm looking at your model and I see that you created a wall. Is that because it's not possible to add a joint that is equivalent to a component vertex coincident with a sketch line?
Yes, joints cannot be applied to sketches. As I showed, you can hide the wall component.
I'm looking at your first pin slot joint and I see you defined joint origins before it. The joint origin on the sliding part is on the vertical edge. Does it matter whether it's on the edge, or could it be an equivalent point from one of the faces? In other words, does Fusion care HOW the origin was created, or only WHERE it is?
In this case the design requirement required the corner contact so the joint must be on the edge. Fusion 360 joints must be placed and oriented to allow the motion required. I used a Joint Origin because it can be re-oriented as needed. Fusion 360 does care how they are placed and oriented.
I was able to make some progress using 3 pin slot joints in the file attached. I used the bottom surface of the sliding block and the top surface of the grounded block. But to my question above, does it matter which surface I pick, as long as I have the right origin?
It is late here, I will look at your model tomorrow.
Again, thank you for the model. I didn't include a model, because my questions are more fundamental, i.e. I don't understand the logic behind these joints. I understand constraints and degrees of freedom, but I'm not sure what Fusion is doing when I create a joint. Could you provide any guidance here?
Thank you!
John Hackney, Retired
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From your model Three Joints, you seem to have the location of the bar using joints all figured out. In your original post, you had an offset from the sides so that is why I used the extra component inside the base block to attach my Joints to. In other posts you seem to shift from the need to use Joints, in the location of the bar, to sketch constraints so I am not sure where your needs really are. I have included another Screencast, showing the use of Contact Sets and Joint locking, using my original attached model, to place the bar in the exact location were it touches the third point. It is just for information as you explore Joints further.
John Hackney, Retired
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