One, everyone is right. Patience with yourself. I NEVER use a striped fabric for big long pieces like in the tube. I cant get the lines even cut straight (the fabric is straight but the design isnt). I used a permanent sharpy marker on my machine to keep myself from crossing past the 1/4 inch line ever and I still use that method 20 yrs later. Next.. your pressure foot if the needle is center is usually 1/4 inch on the right side. FOLLOW It. If your finding your block is a tiny bit smaller you need to work at getting your scant 1/4 inch meaning dont even go all the way to the edge of your pressure foot. Your being too hard on yourself. Go slow (no Mario Andretti foot pedal action) and most of all.. enjoy what your doing. If its not perfect its not perfect. It may still be ok however. Pick patterns that wont show that slightly off line. It makes you feel a whole lot better about your work!