I to have this problem. I'm making a log cabin. measured(I thought was exact)sewed 1/4 seam. 30 of them came out exact or close enough to get away with, then the next 19 are way off. same seam same material that I cut all at the same time, I taken apart all 19 twice and put them back together and they are still off. Most are to small and a few are to big. I ho;d them up to the light and and I can see that the seams line up but for some reason, they aren't right, too small. I think I've had goblins in here working on them after I go to bed.

Hey there,

Universal problem.....the grid on your cutting mat will be incorrect. Use one ruler for width to check for accuracy of the ruler used on width of fabic for strips or squares.
Like a sideways T flipped on the left side.

The other problem is the hand or weight of the materials, if they differ or are used warp or weff or whatever it is called sometimes they will stretch more.

Usually I use a 1/4" foot, if pattern calls for scant quarter, I don't care. If I use a consistant 1/4 all my blocks will be the same size. If you can move your needle
move it one thread with and you will be OK. I am still a beginner and will alway have a zillion things to learn.

Best of the best to you - Cindy