Converting .dae to .fbx with Blender

1. File->Import->Collada(.dae)
2. Usually needs to be rotated by -90 on the X-Axis. If any mesh seems out of place, try rotating in the opposite direction.
3. Make sure there is nothing else present in the scene other than what you want to export.
4. File->Export->FBX(.fbx)
5. Scale by a factor of 100
6. Set Smoothing to Edge or Face
7. Click Export FBX on the top right

Converting .stl to .fbx with Blender

1. File->Import->Stl(.stl)
2. Scale by a factor of 100
3. File->Export->FBX(.fbx)
4. Set Smoothing to Edge or Face
5. Click Export FBX on the top right