how to use mates in slope part solid work

Okay, let's go!
Maybe someone will find it useful, but it's a simple design.. ))

  1. Step 1:

    That what we need for modeling - 2 "i-beams" and "angle-beam"

  2. Step 2:

    Measure distance between planes of i-beams

  3. Step 3:

    and between holes of angle-beam

  4. Step 4:

    The distance of the hole welded lug you choose 75 mm, let's do so

  5. Step 5:

    Make 3D-sketch
    Look at mates
    The distances I made the way I liked, you can make like yours, because it not my project

    2 lines 75 mm Along Z-axle

  6. Step 6:

    Point situated on plane surface of i-beam

  7. Step 7:

    2nd line point - on surface of i-beam #2
    The distance of 150 mm got from my mind to the circle line =)

  8. Step 8:

    Now we must make PLANE for new sketch
    Choose 75 mm lines for that

  9. Step 9:

    Make sketch on this PLANE
    I made 2 lines of 200 mm

  10. Step 10:

    Mates look at screenshot

  11. Step 11:

    Now you must edit i-beam, and using Convert Entities - convert the 200 mm line to plane of i-beam

  12. Step 12:

    Extrude thin and make hole
    Make the same with the 2nd 200 mm line

  13. Step 13:

    But by the reasons you make patterns wrong way and not made configurations, you'll have the lug at all beams
    Not problem, but can be done more perfect...

  14. Step 14:

    And now we are ready to do the mates
    1) Coincident

  15. Step 15:

    2) Concentric

  16. Step 16:

    And this is how it looks now

  17. Step 17: