Contact Sets | When To Use Them And When To Avoid Them |

In this video we try to answer a viewers question about contact sets. This is a tough topic because there are so many applications, but in this video we will look at some common cases when you might want to use Contact Sets and when you just shouldn't.
Contact Sets - a360.co/3BpYCjA
Archimedes Screw - a360.co/3oD97IQ

[@asciimation]

Ah, this is one thing in Fusion I did work out myself. I used it to mock up the motion of the rocker gear in my Riley to work out the best curvature to grind on the rocker arm pads. It got a little too complex for it though as there is a push rod with spherical ends that I found it couldn't accurately model (or I couldn't work out how to do it properly) so I had to split the motion into two halves.

[@LearnEverythingAboutDesign]

Nice work! Fusion did add the tangent relationship which I covered with a rocker arm BUT it also has its limitations.

[@MakeTechPtyLtd]

That's really interesting.

[@dadasut50]

Hello Mr. Matt. Great video as usual Is there a way to natively test the kinematics and dynamics in the CAD software other than exporting to Ansys ?

[@LearnEverythingAboutDesign]

Test as in simulate? Like a dynamic simulation? Fusion does have a simulation option for projectiles if you are trying to understand small movements and material behavior. In terms of movements with contacts that is a tricky one. I have found that Fusion actually handles this better than other CAD, but it really doesn't have a dynamic motion simulation option sadly. Motion Studies found in the Assemble menu allow you to drive a joint or joints and see what the motion is like, but tend to lock up with contact sets.

[@sethother8012]

Ok, but what if i have a situation where I have a mutilated gear, ie teeth on only half the gear. In this situation, a motion link doesn’t do what i want, since i only want the output gear to turn when the teeth are meshing. Imam trying to use contact sets and everything is jamming. Would a proper backlash fix this?

[@sethother8012]

Or is there a third method tgat might achieve this?

[@LearnEverythingAboutDesign]

what happens to the gear when the teeth no longer engage? How does the half gear get moving again? What you might have to do is fake it because true gear contacts can be very processor heavy and tend to lock up. if you can email me a file/pic to support@ caducator I might have a better answer. My first thought is a set of hidden components with a simplified version of your contacts.

[@sethother8012]

@@LearnEverythingAboutDesign The half gear would be the driver. First meshing with a rack, then with another gear. So the output gears move in sequence. First the half gear moves the rack, then it moves a gear.

[@LearnEverythingAboutDesign]

@@sethother8012 Yeah that is a tough one. a360.co/3HN5yKF This one works but the gear to gear contact sets forces it to go crazy calculating the intersections. Gear to rack seems to work a bit better. My only other thought is to do this with some sort of Geneva Mechanism setup where the contact is a cylinder in a slot vs gear tooth interaction.