IF you are talking about the VINTAGE 830 you have 5 needle positions on the dial. I look at them like this:
to the extreme left is position 1; to the extreme right is position 5; in between are 2, 3, 4.
Using foot # 000, a scant 1/4 inch is in position 4. I use a small sticky note pad against the presser foot as my seam guide. It's easily removed for other widths or angles.
Jan in VA