I am working on a BOM and made my first block this past weekend. Everything went together well and the block turned out great, however, when I measured it, it was 1 1/2" too small. The block was supposed to be 12 1/2" square and mine is only 11" square! I don't know what happened! I even measured the space between my needle and the edge of the presser foot to be sure that what I was sewing was a 1/4" seam. I can't find anything wrong. Can someone help me with another way to check to be sure I am sewing the correct 1/4" seam?

I can't say for sure but I have had the same problem with a block before, it had a lot of different angle pieces within it and you couldn't 'square' it up as you went along due to the irregular shapes created prior to completing the block.

Is this the same problem? If not and you can square it up as you go, take the time and determine if a section measures, say 3" before proceeding to attach the next section.

I would test my seam width on a couple scraps and then measure the results. Also it could be that your BOM is not giving you the correct information - I've had this happen. Good luck! If all else fails, you could always make all your blocks 11" - at least they'd be consistent.

The problem might be in your pressing or even the thread. Try 50 wt for piecing. Or it might've been in the cutting. All my piecing tries to "shrink", so I use a scant 1/4" seam allowance when I can. A test to see what you have to do to get accurate piecing on a given combo of fabric, thread, sewing machine, pressing is to cut three strips 1.5" wide. Piece them together and press the center strip should be exactly 1". If not, try troubleshooting from there. I still struggle with this after 20+ years of quiltmaking, especially when switching machines. One big factor for me was thread. Switching to 50 wt Aurifil or Masterpiece by Superior Threads has helped a lot.

Check your cutting as well. If the line of your ruler is off the fabric even a little, your piece will be too small. I still struggle with blocks coming up too small so I cut a tiny bit bigger.

Is it possible that the seam allowance wasn't added to the pattern??

I know what you are talking about, I have had the same issues. I am careful with my cutting and happy with it. Thought I was doing a 1/4 inch seam, but when I put the darn thing together it was small, I was to end up with a 16 inch square, but it was not. So, I started to sew with a scant 1/4 inch and make sure the fabric is going through the machine, it is going straight, especially at the end. You would be surprised how many times I check and it veers off one way or the other. And that is a pain when you go to piece this block together. It is not the right size. I have had more luck with accuracy doing both of these things. Good luck, it is frustrating, I have a lot of...what the heck? moments.

That's what I was thinking. Re-check the pattern to see if the seam allowance is included. If you need help with that, I am sure someone would help if you posted the block along with cutting sizes.

To shrink 1.5" would take a lot of seams!

Sew 3 strips of scrap fabric 2" x 6" together. The strip set should measure exactly 5". If it doesn't, then you are not sewing a correct 1/4" seam. You can adjust accordingly. If you can move your needle position to the left or right on your machine, try doing that to get an accurate 1/4" seam. Then do your test strips over again with new scraps. A quarter inch foot helps also. Personally,I like to sew a "scant" quarter inch which means you need to sew a thread or two less than 1/4". By sewing a scant quarter it gives you a little allowance for the seam and pressing. That works well for me.

I have had trouble in the past with all my blocks in the BOM club not being the same size and rather than tearing them apart and redoing them, I have put a 1" - 1.5" border around them and then squaring them all up to the same size.

I have been sewing and quilting for years and years and I still struggle with 1/4" seams. I just bought a quarter inch foot for my machine that has a metal bar on it so that the fabric doesn't shift past the bar. I think it helps. As for your block it really sounds as if the pieces don't have the 1/4" seam allowance added to it. That's the only thing I could think of that would make that big a difference.