I want to build some heavy-duty racks with four wheels each as follows. The load is not more than 500 kg. The frame is made of slotted angle iron and the board is about 8mm thick.
The available wheels are
What is the easiest way to attach the wheel? There are two kind of wheels here, with a bar that must be inserted to the frame or a flat base wheel.
Edit
I found from the internet:
What kind of base plate is it?