Go to 'edit - current drawing preferences - paper' and set a paper size first. In 1:50 it won't fit on A4 or A3. Be sure your printer is set to the same size. Then go to print preview. You will see the paper sheet in white under the drawing. Set the printing scale desired. If it doesn't fit on the largest available papersize you can set a smaller scale like 1:100. You can shift the paper to the wanted position with the mouse. And print!