weapon bones not working as expected

I want to be able to animate the weapons of my characters independently from them. The Mannequin Skeleton has dedicated weapon bones that, as far as I can see, hear and read, are meant to enable exactly that. Even taking a look at the paragon characters it appears like that, as their included weapons can be moved freely from the rest of the mesh via the weapon bones (Only difference being to my case is that I dont include the weapon mesh in the character model, because I want to switch weapons in my project).

So I thought “nice, they already set that up as default so I can use it”. So I went into Cascadeur (animation programm) to make an animation. There I realized that i cant move the hand bone without the weapon bone following, due to it being a child of the hand bone. No problem, just add a transformer object thats not part of the bone hierarchy and constrain the weapon bone to it, so I can dynamicyally “bypass” the relationship induced movement of the weapon bone if needed (weapon out of hand).

This works absolutely fine in Cascadeur as seen here

However, Cascadeur bakes every interpolated frame into a keyframe upon export automatically, yet, after importing into Unreal the weapon bone is jiggling for the time period it is not at the same position as its parent (hand bone). This does ONLY occur BETWEEN the keyframes where Unreal applies its own linear interpolation. Essentially, the movement of the hand bone, influences the weapon bone between keyframes as seen here and here

It becomes more obvious looking at this

I dont know what to do anymore. I know finding workarounds is the normalcy in gamedev, but I somewhat refuse to believe that I cant just use the Mannequinn SK, which is absolutely made to what I want. Im by far not the first person wanting to seperate weapon from character animation, but the logical obvious, and by EPIC themselfes provided way to do that, doesnt work as expected.

What can I do? Please, Im at my limits after a week of trying things and searching every corner of the web for a solution…

Hello @MojoSwipsi1, I’ll try to help you with that…

First, are you sure that Cascadeur bakes the animation automatically when exporting? This type of animation should actually work pretty well without any additional set up, so maybe something is going wrong with that.

You can check it by importing the exported FBX into Cascadeur or another software and check if the sword moves at all. You could also check it by setting the animation interpolation in Unreal to Step:

This will remove the interpolation between frames and you can ensure that the animation is correct. I’m suggesting it because we can see in the last video how the sword constraint in Cascadeur is constantly moving, just like in Unreal, so perhaps it’s either baking it wrong or not baking at all.

Please let me know how it goes, but this shouldn’t happen if the animation is properly baked.