topic Re: Pin Slot Joint Will not Rest for Distance in Fusion Support Forum

Pin Slot Joint Will not Rest for Distance

wfarren — Thu, 22 Apr 2021 16:12:57 GMT

Hi. I've inserted a pin slot joint but cannot get it to rest for the distance portion of the joint. Also, was wondering if there is a way to speed up a contact set (or cache the movement) for better performance while moving the joint in real time. (I added a small sphere to the front of the screw component in the video posted, in order to decrease contact between surfaces on the contact set, but that does not seem to help performance.). In the video, I did not mention that the cylindrical joint used for the screw has a motion link so that one full revolution of the screw moves it .85 mm linearly. That seems to be working fine.

Update: I suppressed the contact set and set up a motion link between the cylinder revolve joint and pin slot slide joint and that seems to work well as far as simulating the screw being turned and the spreader moving in and out. Still can't get the rest on the pin slot slider to work, however.

Thanks in advance for any suggestions.

Re: Pin Slot Joint Will not Rest for Distance

jeff_strater — Thu, 22 Apr 2021 17:16:00 GMT

you have correctly identified contact sets as the source of the slowness. Definitely don't recommend using contact sets for anything but trivial geometry (I sometimes use them to help set up the limits). And no, there is no way to speed them up, unfortunately.

Regarding the Rest issue: can you share your design? would need to see that to try to figure out if it is a bug or an issue with your design. Thanks!

Re: Pin Slot Joint Will not Rest for Distance

wfarren — Thu, 22 Apr 2021 17:38:32 GMT

Hi Jeff: Thanks for the reply.

Here's the design link: https://a360.co/3axat11

For the rest issue, not sure if it's a bug, user error, or maybe there's a reasonable work-around.

Best,

Re: Pin Slot Joint Will not Rest for Distance

jeff_strater — Thu, 22 Apr 2021 21:23:45 GMT

initial findings: It is related to the motion links and the cycle of joints. If I suppress the motion links and one of the revolutes, the rest position works. However, if I unsuppress any of those, the rest fails. You can see in the screencast that if I just suppress the motion links, it is trying to return to the rest position, but doesn't get there. But suppressing one revolute and unsuppressing the motion links also fails to solve correctly. I will turn this over to the joints team to dig in deeper. Thanks.

Re: Pin Slot Joint Will not Rest for Distance

wfarren — Fri, 23 Apr 2021 08:35:22 GMT

Okay. Thanks for taking a look.