The drawing space in a CAD system cannot be limited to a paper. This is one of the differences between a CAD system and a simple drawing or office type utility.
Some things to keep in mind:
- Everything you construct in CAD is constructed 1:1, no matter if it's the floor plant of a house or a tiny part of a wrist watch.
- Your drawing is not created on an A4 or any other paper size. It is created in 'model space', 1:1, no limits involved.
- A scale factor and paper size is applied to your drawing only for printing.
- Since the arrangement of dimensions, the size of texts and hatch patterns depends on this printing scale of your drawing, you always have to be aware of the final scale you will print the drawing in.
- Elements with a fixed size on paper (such as a drawing border) have to be scaled inversely to the drawing scale factor. If your drawing scale is 1:100 and your paper is an A4, the border has to be drawn about 100 times larger than an A4, e.g. 21m x 29.7m.
- The QCAD part library has some borders, but you will most likely have to create your own to satisfy your requirements. Start with a simple A4 size rectangle and improve from there. Keep the border on a separate layer, so you can easily show / hide / select / modify it.
Please refer also to the printing chapter in the QCAD book.