Combined joint help please

[lilraptor40]

So I'm relatively new to Fusion 360 and have found myself stuck on a certain type of combined joint. It's two opposing sliding joints that have arms and the arms are attached at their bases with a rotating joint. I'm trying to link them and just keep getting a warning error that it doesn't work when I create the lower rotating "revolute" joint.

I can't figure out the combination of joints or how to motion link them to get it to work. I was able to use the "enable all contact" without making the lower "revolute" joint, but it just worked for a couple of movements and then popped out the bottom joint. Even though I had it centered.

So I'm including a sample Fusion 360 (.f3d) file of the type of joints I'm trying to do. This isn't the design itself, but it's a good stand-in for what I'm trying to get done in my actual design. Below is a screen capture of the type of motion I'm talking about for further visual reference.  

The movement I want to achieve.
Thank you in advance for any help. I'm really stuck and this sucks lol. 

[kb9ydn]

Is this what you're trying to do?

C|

[lilraptor40]

Yes! That's exactly it, but how did you get it there? I see the pin-slot joint is what I didn't have. Thank you for showing me that. I was using slider joint before.

I tried to use your timeline where I do the simple joint origins first and then the revolute joint on the bottom joint. But it still gives me the warning when I do the final pin slot joint up top. I can't get it beyond the warning. I looked to see if you had joint limits set, but it doesn't show any. If I do only one pin-slot and the bottom revolute, then enable all contact it works. It's not the same as yours, still pops out if I grab the bottom joint only, and I see you were able to do all three joints. 

Thank you for your time so far. You rock!

[jeff_strater]

 @kb9ydn beat me to the punch.  Same idea, but since I built it and recorded a screencast, I'll second that approach.

One difference in my design, because I was too lazy to build accurate geometry, I used a Cylindrical joint instead of a Revolute

screencast:

Screencast will be displayed here after you click Post.

035c4582-d493-4995-a1d5-259d2afe5b6d

[lilraptor40]

Thank you for replying @jeff_strater but for some reason all I can interact with is the .f3d file on your post. Which I downloaded but my guess is the screencast is needed for reference and for some reason the screencast isn't visible. All I see is "Screencast will be displayed here after you click Post." I don't want to sound like a complete newb, but no matter what I click all it states is that message. Here is a screenie of what I'm seeing.

[jeff_strater]

weird.  I've seen that happen to others before.  Here is another go at it:

 (there is audio) 

Screencast will be displayed here after you click Post.

035c4582-d493-4995-a1d5-259d2afe5b6d

[sanket223.patil]

Hey , I have first add as build joint between arm and bar , same for other . After I Had a revolve as build joint between two arms . To add control for pin slot I enable contact set and added new contact sets between arms and bar .

[kb9ydn]

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@lilraptor40 wrote:

Yes! That's exactly it, but how did you get it there? I see the pin-slot joint is what I didn't have. Thank you for showing me that. I was using slider joint before.

I tried to use your timeline where I do the simple joint origins first and then the revolute joint on the bottom joint. But it still gives me the warning when I do the final pin slot joint up top. I can't get it beyond the warning. I looked to see if you had joint limits set, but it doesn't show any. If I do only one pin-slot and the bottom revolute, then enable all contact it works. It's not the same as yours, still pops out if I grab the bottom joint only, and I see you were able to do all three joints. 

Thank you for your time so far. You rock!

---

I had joint limits set but it should work without them.  What warning are you getting?  Without knowing what that is it's hard to say what's going wrong.  One thing I did have to do with the revolute joint though is to add a small Z offset so that everything would line up (because of the part thicknesses you don't have direct planar contact).  Without that offset it won't work.  Also, I didn't use contact sets at all.

C|

[chrisplyler]

Don't use Contact Sets. They don't work well. The only thing this needs is two Pin-Slot joints and one Revolute joint. The positions of the Pin-Slot joints and their Limits have to be set up properly.

Click on my fd3 file attached at the end of this post, and select the option to Open in Fusion 360.