How do you combine each joint？

[Y-Lee1]

I add my model, they all come together at the origin, how do you get your joints to fit together

[Minhtrna]

Hi, I have done something similar.
To ensure the components are in the right place, you should use the model file provided by the manufacturer. They usually come in stl or step format.
If it is in STEP format, you will convert it to glp format. Then you use Blender to open the converted glp file, which will contain all the parts of the model. From blender, you can move, rotate or do something to get the parts in the position you want. Then you select all the parts you want to use and export them as STL files. To export the selected parts into small files according to this project, don't forget to tick "Selection Only" and "BATCH".
This will create stl files of each part in the right position, then you just load it in and it will be in the right place.
In STL format, I haven't tested it yet, but I think it will be similar. Good luck