I am never real accurate either but I find it I do the same thing everytime and even if it is a little off on each block the only difference is the size of the quilt If it is 2 or 4 inches smaller add a border to it. I am by far not great at piecing. As long as you can square all the blocks to the same size I have had success!

Tartan has it. the black lines are to be used as the target or site or sight where the fabric should line up.

I used to have trouble sewing 1/4 inch, and I finally figured out it was the 1/4 inch foot I was using. I was using the foot with the little piece of metal hanging down. In hindsight, I think I was jamming the fabric up agains that too much, causing a slightly larger seam. When I changed to a 1/4 inch foot without out that metal piece hanging down....a clear foot so I could see through it, I found out that worked much better for me.

Maybe you are doing a similar thing? Or maybe you just need more practice. (I needed more practice also. I was pretty impatient with myself, expecting to conquer the 1/4 inch seam quickly because I had been a seamstress all my life, but I had never even thought of a seam smaller than 5/8 inch. I was just very impatient with myself.)

Dina

All excellent ideas. The smaller your blocks and the more seams in it, the greater chance to come up "short". If the "experts" at quilting saw how sloppy some of my techniques are--gasp!! Sometimes I use the markings on the well-worn mat, sometimes I use a ruler and I have 3. But excellent idea to use the same method/ruler throughout your project. I even use bobbin thread on the big spool that JoAnn's has on sale--good price/lots of thread. But it's skinny so it presses down well. One thing that hasn't been mentioned--I use the foot like Dina has. If I'm looking for a scant 1/4" seam, which you will probably want if the block has a lot of seams, try moving your needle one tip to the right. With mine, there is room to do that without the needle hitting the foot and I get better results. I hope your machine has that feature on it. It has been a big help to me.

This is my way. As long as it's consistent, I am fine with it. Of course, my quilts are just for me or family/friends.
When quilting, I find that 'smidge', 'smidgen', 'scant, 'just a bit' just seem to frustrate me.

I teach to always have the ruler on the 'good' piece cutting into the extra. So often the cutter can slip just a tad and cut into the fabric. If the piece you want is under the ruler, then your slip will be into the extra. Your line on the ruler should be on top of the line of the fabric, not to the left or right of the edge. Also, make sure you are holding the cutter straight up and down. Not only is this more accurate, but it is safer. Until you get your cutting more accurate, cut slightly bigger and trim the blocks down (if the pattern allows for this).

I have quilted for almost 20 years and close enough was good enough especially when you are doing the same block over and over. I an now working on "The Orphan Train" with 6 " blocks. Last night I spent quite a bit of time getting that 1/4" seam. I finally got it on my main machine. In order to get it I have to lay the ruler cutting line just a tad to the left of the fabric and also use a Scant 1/4. Then I worked on me 301 that I take to classes. I think I have done everything I need to but I have Aurifil thread and will use that. I think that will make all the difference. Thanks everyone for your help.

I do not deliberately cut "a smidge" larger - that is just a result of the distance the rotary blade cuts from the edge of the ruler - so I measured it to see how much that distance is.

Use the suggestion by Paperprincess. Also do you have a 1/4 inch foot. They are my favorite foot. Although you need to figure out exactly how to use it also to achieve a perfect 1/4 inch seam. Every machine is different. Even machines of the same brand. I need to move my needle over one click to get a perfect 1/4 inch.

I, too, think my piecing is off just that 'hair' that it's my cutting as well. I know I am not consistent. The other evening working in very dim light, I tried using some post-it notes on the ruler line and, honestly, it didn't help in that particular situation. I was only trimming batting on a baby quilt so wasn't overly concerned. I keep telling myself when I'm thinking about quilting and not actually quilting, that I must remember to use some painter's tape on my ruler to get my cutting consistency better. But then I forget when I get to the sewing room. Sigh. One of these days.