Hi Cube,
I'm going to guess that the reason that you're not getting grid lines when you print a table in Numbers is that you haven't actually put any lines on the grid yet. In order to put lines on the grid (what Numbers calls Cell Borders), you need to go the the Inspector and select the Table tab. Then about half way down the page you will find a section titled Cell Borders. After you have told Numbers where you want the lines to be, and what type lines (solid or dashed), and how thick, and what color, you will be able to print them.
Hope this helps.
Jerry