I’ve recently been trying to CAD a 4 bar lift in fusion 360 although when I try to join the bars together using the “joint” function with the “revolute” type of joint fusion tells me “selected joint type will result in conflict” and then none of the joints work.
Thanks in advance
I’ve never had any formal training with Fusion 360, but I have been using it for the last 4 years just learning as I go. Here’s my method for creating motion links such as a 4-bar. I’m not sure if this is inferior to other methods or not the accepted standard, but here’s what I do.
- Position the components using the move and align tools.
- Create a number of As-Built Joints at each of the points of revolution (where you would have a screw or an axle). Specify rotation as the type. The As-Built Joint tool will revolve the first selected component around the second selected one. You will specify either a construction axis or some object geometry as the rotation center. Note that this required design history to be enabled.
- At this point you should be able to rotate each individual bar. If you are not able to or the whole assembly moves, ground a stationary component and try again.
- Create a number of motion links between your joints. You can modify the ratio of speed and the direction to match what should physically happen. Motion links must be done in pairs, so pair off the joints and apply a motion link to each pair until you have the minimum number of constraints for the system to properly work.
Ok thanks for the help - I’ll try
I have also been using fusion 360 for about 4 years, you had a nice explanation of the joints. I would just like to add that it also helps to have restrictions when creating motion links.
Fushion 360 is so difficult to use
if you watch tutorials and just understand some about modeling its not bad.
it takes some time to perfect
Try to label all of your joints so if there is conflict with another joint, you can easily go through and find the problem.
A small tip that might save you a lot of time is using rigid groups instead of multiple as-built joints. They achieve the same thing, but rigid groups are far more efficient. (Select all pieces you’d like to join, right click, and make rigid group)
Moving parts into place is also never as efficient as using joints, so I would build 1 side of your lift with regular rigid joints, using revolutes any time a bar should rotate. Get this side working first, using motion links or a motion study might be more intuitive and is render friendly. Then you can mirror the lift, and constrain the mirrored side with a few rigid groups and revolute joints. If you want to make things even simpler, you can include the original(not mirrored side) bars in the (mirrored side) rigid groups accordingly so that you don’t need the second set of redundant revolute joints.
Thanks - I never thought of this - this really helps
I think if you want to preserve the joints on your mirrored lift, you have to make a new project and import two of each side of your lift. I once used mirror and did not preserve the joints I made on the original side.
That’s correct, which is why I make rigid groups that span the lift and connect the unconstrained parts to the constrained original parts.
If you use lift subassemblies, selecting the proper components for making your spanning rigid groups is much faster as well. Adding subassemblies can be done after assembling a side, so contrary to popular belief you don’t need to be thinking way in advance. Just create a couple new components, name them, and drag and drop your existing components into their properly sorted subcomponents.