I feel like this should be a bit easier as I've done this years ago in 3ds Max without the same trouble. What I'm wanting to do is model two legs (1 object), a skateboard (1 object), and an arm (1 object) for animation to import to Unity as ONE character mesh for an fps controller. I downloaded all of these meshes from free 3d model sites and posed them together and saved the Frankenstein as one model.
My trouble is when I animate them together in Blender (for an ollie animation) it looks great but when I import the FBX to Unity the board is in one place, the legs and arms are in another and the animations are all split up separately between each mesh, with no one animation showing the whole thing. I rigged bones for the legs object, then bones for the arms object, but did not put bones in the board because I don't need it to bend or deform at all (just spin and rotate and go up and down as one whole object). I tried adding one bone to the deck of the board but when I weight paint and try to pose the bones it only takes the deck of the skateboard with it and not the trucks or wheels. When I animate it all, using pose mode for the arms and leg bones, and object mode for the board, it seems to work fine (even great) in blender.
When I export to Unity everything goes to hell. There's about 95 separate animations that show up. They seem to be all separate pieces of the meshes from the "Action to be linked" part of the blender action editor which has the "fake user/users" buttons but I'm pretty new to Blender and especially new to Blender 2.8. In Unity only about 5 of the 95 separate animations for this one fbx actually show movement but none of which show all of these objects animating at the same time like it shows in Blender.
I've been searching forums, google and youtube for a week now and not sure where my problem is. Should I attach all of these separate objects together before rigging and/or animating via Join or Parent? Do I need to make bones for the board (even though I don't want to manipulate the mesh of the board at all)? I've tried parenting the board mesh to the leg bones and reanimating but it hasn't helped. The board always seems to be the most deformed and out of place in Unity. The animation seems great in Blender and I hope I'm just some clicks away from being able to fix this without reanimating but I'm starting to feel like something went wrong along the way.
Can anyone point me in the right direction? I've looked at attaching guns to hands but I don't need the skateboard to necessarily be attached to the legs when animating the jump as I'd like it to flip and legs catch.