thats the problem with european machines !!
the saw your are refering to is a european machine,
the top is made of alloy or flimsy pressed steel i assume.
unfortunately there are a lot of so called safety restrictions with these machines, an arbour only long enough for a single blade being the main one. i own an electrabeckum pk 200 precision saw myself, the arbour consists of an allen screw and flange washer which screws reverse thread to the 1/4 inch of arbour that protrudes from the self enclosed universal motor ( another problem) so its impossible to fit anything other than its own blade.
it is nearly impossible to buy a saw cappable of accepting a dado blade throughout europe, and very expensive to buy a machine with a cast iron top.
the topic of dado blades is red hot in the uk with a lot of the woodworking magazines shunning the use of them.
sorry for banging on !! hope this sheds a bit of light for you redgum.