How I can place a screw exactly at the central axes of the bone?

[svmjack]

Hello, I want to place a screw exactly at the central axes of the bone specified in the picture. How I can do it in the assembly part?
Best Wishes.

 

[Cadasio]

Without seeing how it was constructed I can only guess..

Switch on temporary axis - though I very much doubt that will help in this case
Use an existing sketch/reference plane that was used in the creation of the part
Create a 3D sketch that represents the axis
Create an axis manually, either from points on the model, sketches or planes

Since you're asking I think you are going to have to manually create some references to create the ais, however, I can't see anything obvious (doesn't look symmetric, etc) you can pick up - if you share the part I could probably help further?