Great information. I have a Slimpicity and I can only move my needle to the right or left. Are there machines that the needles move more than that? I use the outside of my foot and I seem to get a true 1/4" seam and it works fine as long as I pay attention all the way to the end. When I have to try for a scant I am not sure what to do. Any help would be appreciated. How do you cover the feed dogs? Thanks for the thread. BrendaK

Well, thank you so much! In the quilt classes I have taken, no one has every addressed the quarter inch
sewing problem. You make it very clear and I really needed this info years ago. Thought I was just bad at
stitching accurate 1/4" seams. :D

Thank you so much for posting this!

An index card also works great.

I always pass this along to beginner quilters.Thanks for posting tute......

Thank you. That accurate seam allowance is so important.

Unless I was making a quilt for a quilt show and I never will, as long as all my seams are sewn the same my quilt may be an inch smaller in the end but it will all work out. When I made my first quilt (my aviar) no one told me points were hard, no problem here, or that the seam allowance made a difference, no problem again, my quilt may not be the exact size but keeps me warm, fits my bed and even tho it was a first and I just bought quarter yard cuts it worked out just fine. This is one thing I do not stress over. And horror of horrors I used a sheet for the back and hand quilted it

The center strip should measure one inch "finished" width - the part that will be "showing" when the item is complete.

The "unit" of three strips should measure 3-1/2 inches wide after sewing the three strips together.

Another place where fabric can "change size" - if/when pressing unwashed pieces with steam - once in a while some of the pieces shrink.

I have measured hundreds of pieces of fabric before and after washing (my method - which involves using hot water) to see if, in fact, there was shrinkage. in most cases there is some shrinkage. I have had shrinkage of over two inches in width in the Michael Miller black. Most fabrics seemed to shrink more in one direction than the other.

Because I prefer a flat as possible finished product, I do the wash before cutting process of all washable components - but many people feel that doing so is a waste of time, effort, water, and detergent.

I just washed some very tightly woven cotton fabric that I would have sworn would not shrink at all - it shrank over an inch in length!

I have noticed that several bag/purse patterns (Simplicity) are now saying to wash the fabrics before starting.

As others have said - seam width is only one of the places to look/consider when things are not turning out as expected.