PaperPrincess

Tutorial here:
http://www.quiltingboard.com/t-89997-1.htm
you really do need to figure out where on your machine this is. If your quilt is made up of all the exact same blocks, then just being consistent will be just fine. As soon as you try to piece one block with 3 seams next to a block with 2 (or 4 or 5) seams, you will start to have problems.

Kat Sews

The quilt that was off by less than 1/16 inch would have been accurate regardless of how many different styles of blocks were in it. I did the math first to determine the correct size (13 8 inch blocks plus one 3 inch piece to balance the frame plus 2 unfinished edges equals 107.5 inches) and the measurement was within 1/16 inch. I like to enjoy quilting and am glad I don't have to stress over 2 threads.

ghostrider

That's just not true. All of the blocks will be the same size, no matter what blocks you make, if your seams are consistent. The seam width may, or may not, affect the final size of the blocks, but they will all be the same no matter how many seams are in them. Otherwise you'd never be able to make any quilt with more than one type of block in it.

I never use scant seams and it's never made any difference worth mentioning, in fact it makes for flatter, squarer tops and a much happier quilter when they're done.

Prism99

It's true that the size of the seam will not matter as long as you are making a quilt out of all of the same block pattern, or all of the same block pattern alternating with plain blocks.

Problems arise quickly, however, when you want to make a quilt that uses multiple types of pieced block. The most obvious example would be a sampler quilt. Even if your seams are a consistent size, every block may end up a different size because their patterns are different.

I'm trying to think of two block patterns that would illustrate this clearly, but my mind is blank. I found this article that tries to illustrate the problem:
http://www.scrapquilts.com/accurate_seams.html

There isn't so much of a problem when you are dealing with squares. The problems start to become more obvious when making blocks with star points.

I'm thinking there would be problems even with a feathered star if you cut all the pieces out first. If the star strips are not sewn with the correct 1/4" seam, they will not fit the already-cut center squares. If you know this in advance, you can make the strips first and then cut the squares to fit the star points. However, again you may have the problem of the feathered star block not being the same size as another block featured in the quilt.

Those of you who have not had a problem probably are using scant 1/4" seams without realizing it. Since all block patterns are sized assuming an accurate finished 1/4" seam, all block patterns will come out the same size for you if you happen to be using a scant 1/4" already.

Parrothead

I am quite sure my Grandmother and Great-Grandmother never heard of a scant 1/4 inch. All of their quilts are beautiful. Grannie pieced and quilted 10 stitches to the inch. I do not think I will ever get there! LOL