Double-check your quilt rulers and make sure they're square. I have two frosted Olfas and discovered by accident (I was using the ruler to draw) that 2 of the sides are off by 1/16th of an inch - on BOTH rulers!. You may not think that's a big deal, but after 2 blocks that adds up to a quarter inch!

My log cabin blocks don't turn our pretty like some I've seen. They seem to curve in the center of log. Am I cutting material in wrong direction? does anyone else have trouble with them? Thanks for any advice.

.......... even if it's not as large as 1/8" and just a thread or two off ... it multiplies incredibly!
And if you do 1/4" on one strip, but not the other ....!!
Or ... if it's 1/4" in the centre of the strip and gets narrower at the end(s) ... well, you get the picture, though it seems a lot of others don't! :) :(

Jeandrig, do you cut your stripes to size before you start or do you string piece? I am trying to understand which part is curved. Do you press each seam after it's sewn or do you fingerpress? Are your seam allowances a consistent size? Are you careful to keep all the seams going the same direction? I found that I do better when I sew one block at a time rather than string piece. That way I always turn the block in the same direction and add the correct color (I don't do scrappy in log cabins).

Glad to see this, I took a quilting class for beginer's long cabin, dark side & light side. 8"blocks. I thought I was totally
unable to cut. It forst my blocks were pretty good. The lady said we need to for them exact. My were some really goo,
some 1/8" off one 1/4". We all neeed to iron and make blocks to a plastic sq. she had. Which would have been great but that is where most of ran into to trouble. The more we played with them remaking & iron he worst they became.
My friend was beside me, said she knew better than to mess with her sq., unless the were more tan a 1/4" off. She just sewed and adjusted on seem lines. Her did better than most. Which is better to redo or make up in sewing?
It has bothered me so, not knowing and should a log cabin be your first quilt. Maybe I am just a slow learner.

Glad to see this, I took a quilting class for beginer's long cabin, dark side & light side. 8"blocks. I thought I was totally
unable to cut. It forst my blocks were pretty good. The lady said we need to for them exact. My were some really goo,
some 1/8" off one 1/4". We all neeed to iron and make blocks to a plastic sq. she had. Which would have been great but that is where most of ran into to trouble. The more we played with them remaking & iron he worst they became.
My friend was beside me, said she knew better than to mess with her sq., unless the were more tan a 1/4" off. She just sewed and adjusted on seem lines. Her did better than most. Which is better to redo or make up in sewing?
It has bothered me so, not knowing and should a log cabin be your first quilt. Maybe I am just a slow learner.
We needed to make all blocks before putting any together. Oh, well I still have 1/2 my block to redo. after fixing them the first time, it seems the more I work on them the more off they get.

I'm like Sandy I, I like to paper piece LC blocks. Then they come out perfect and you don't have to work on squaring them up each time and they fit together perfectly.

Paper piecing is much more time consuming
 

Paper piecing is much more time consuming than strip piecing a Log Cabin Quilt. If one has used strip piecing, I don't think she would want to paper piece. It is better to square up as you go along, but can be done by the whole block like Mad Quilter or Kat Sews said. Yes, cotton stretches and that is one reason that the blocks are not square even though you have been meticulous with sewing each strip.

Kathy

I'm wondering if they're curving when you press them - are you moving the iron across the fabric, or up and down?

This may not be what you want to hear, but I was looking at a Nancy Zieman & Natalie Sewell book (Landscape quilts) and there was two pictures vases with flowers. I was struck by how immediately I loved the one while the other was only OK (to me). I asked DH (who is my critic and helper) which he liked best and he chose the one I was drawn to. The big difference..... one had a carefully measured vase that looked somehow sterile, and the other had a vase that was a wee bit off shape, as if it were hand crafted, perhaps on a wheel, but by human hand. It was graceful and somehow more lovely. Maybe log cabin quilts don't have to be so "careful"; maybe a little off adds to their charm. Or maybe I'm a weirdo (married to a weirdo) and everything should be absolutely perfect and keep the quilting police happy.