The three steps to clean your seed. (EXAMPLE)                                                                          

 1       PRE- CLEANING

         - Rub the seeds out of the flowerbulbs
        - Place the handscreen size
φ 5,0 over the funnel
        - Adjust the funnel opening to 2x seed diameter
        - The airspeed must be regulated so that when the seed/chaff mix falls trough the top screen the chaff and
           the light(bad) seed will be blown away and the useable seed will fall into the collection tray

        You now have one batch of roughly cleaned seed.

2        SORTING TO SIZE

        - Put handscreens  φ 2,5 - φ 3,0 - φ 3,5 - φ 4,0 and φ 5,0 on top of one another (φ 2,5 at the bottom)
        - Drop the seed slowly from the collection tray onto the top handscreen
        - By shaking the stack of screens gently the seeds will fall through

        The batch has now been sorted into 6 diameter sizes:           Contents of φ 5,0 screen     - seed > 5,0
                                                                                                Contents of
φ 4,0 screen     - seed > 4,0 - < 5,0
                                                                                                Contents of
φ 3,5 screen     - seed > 3,5 - < 4,0
                                                                                                Contents of
φ 3,0 screen     - seed > 3,0 - < 3,5
                                                                                                Contents of
φ 2,5 screen     - seed > 2,5 - < 3,0
                                                                                                Bottom      
φ 2,5 screen     - seed            < 2,5

        Remove the screens from each other and there are the sorted seeds.  Clean the screens.

3        CLEANING UP

        - Place handscreen size φ 4,0 over the funnel
        - Adjust the funnel opening to 2x the seed size
        - Now take the seed batch > 3,5 - < 4,0 and adjust the airflow at such a speed that when you gently drop
           the seeds onto the screen the light(bad) seeds will be blown away and the heaviest/best seed falls into
           the collection tray

        Repeat the above steps for all the different diameter seeds, you can change the screens if need to.