Here are pictures of two blocks...the front and back. I end up squaring up all the blocks to 6 1/4.

I wrote this response on another thread - same question/problem - so I'm just going to assume you were working on a star block:

If you could post a picture of your block - front and back - it would be really helpful.

Without seeing the blocks, I'm going to say the problem goes back to the basics - cutting, pressing and sewing.

And it has nothing to do with being the quilt police , but at some point, if losing your points bothers you, then you have to take the time to get a really good understanding of how those three actions affect the construction of the block.

I have no idea what your experience level is, so I'm just throwing the following out there. Don't take it personally if it doesn't apply.

So here's how all those things can affect the block:

If you don't get the cutting right, it's not going to "fix" itself down the road. Same for the pressing and the sewing.

So, either your sub-units weren't constructed properly, which would cause problems when you put them together, or when you sewed them together , there wasn't a good and consistent 1/4" seam allowance.

If you look at the back of the block, was the allowance straight and even for the entire length of the seam , or did you sort of lose it at the end and it got narrower? That's going to cause you to lose your points when you sew that block together with another one.

How did you construct the star block? There are a gazillion ways to do this, some of which give you more control and avoid dealing with any bias edges which can cause stretching.

Pressing - were each of your subunits pressed well - meaning the seams were set, there were no creases or tucks when you folded back the fabric, and the whole piece is as flat as wallpaper?

One of the best books I've ever read that really explains how all these things combine, when done correctly, to create a perfect block is Sally Collin's "The Art of Machine Piecing."
http://www.amazon.com/gp/offer-listi...condition=used
It's a great deal for under $7.

Sally is a bit....anal (and I mean that in the best way), and you don't have to follow her every step. But at least when something goes wrong, you'll know exactly what caused it and how to correct it.

Anyway, I hope you get a chance to post pics of some of the blocks.

Your seam allowance may be just a touch too large.

That's what I was going to say.

Here are pictures of two blocks...the front and back. I end up squaring up all the blocks to 6 1/4.

ok, so if my seam allowance is a bit too large, and I'm doing a fence rail, how come the sizes are different from one another? In that I mean, the two pieces after sewn together, one side lines up exactly and the other is shorter. Did I make sense. I'm very careful, but obviously not careful enough.

One fabric may be stretching just a tiny bit, just enough to make them different.

You also have to make sure that you're cutting the exact size to start with.
Is the line on the ruler on the fabric or off or half-on?

And, in the case of your particular block, how big did you cut the HST's for the corners? You're dealing with bias edges and something could have gone a bit wonky there.

**As an aside, for a block like that, I would have cut those HST's a bit oversized, and then trimmed the whole block down to the 6.5" final unfinished size that I need. **

By trimming the blocks down, it looks like you're going to lose a few points when you join the blocks together. It's not horrible or the end of the world. It happens.

Again, it's a combination of the cutting, sewing and pressing.

Spend the $7 for the book. It's so worth it.

I would just add one thing to MTS's good advice. Whenever working with bias pieces starch your fabric really well before cutting. It will make your cuts more accurate and help keep the fabric from stretching.

Like MTS, I always cut triangles larger and trim after sewn on. It's a mystery to me, but I swear triangles shrink after you cut them. LOL