A log cabin block is a square of fabric with strips sewn around it, one after another, always turning the same way. That is the whole pattern. It has been in quilts since the 1800s and still turns up in modern ones, because changing the fabrics gives you a different quilt out of identical construction.
Melanie Ham builds hers from a jelly roll, and her version has one wrinkle worth copying. She never gets up from the machine during a round. Strip on, sew, snip, finger press, turn, next strip. Four logs go on before she walks to the iron.
Why it is called a log cabin
The strips are the logs and the center square is the hearth. Traditional blocks put a red square in the middle for the fire, and some quilters used yellow instead to mean a lamp lit in the window. Nobody needs that detail. Everybody remembers it, and it is a good reason to make the center square count.
The light half and the dark half
A classic log cabin splits down the diagonal: light fabrics on two adjoining sides, dark on the other two. On one block the split looks subtle. Sew nine together and rotate them and those halves line up into diamonds, zigzags, or the concentric rings quilters call Barn Raising. Same block, different turn.
Value matters more than color. Squint at your strips, and if two of them go the same shade of gray, they will not read as separate logs no matter how different the prints look up close. Choosing quilting fabric with contrast in mind makes or breaks this block.
Jelly roll strips or cut your own
A jelly roll is roughly 40 precut strips, 2.5 inches wide and the full width of the fabric, all from one line, so the colors already work together and the width is already right. Cutting your own gives you more control and a cleaner edge, and the usual rules for cutting quilt fabric apply. Precuts arrive with a pinked zigzag edge, and measuring from the wrong side of it is a quiet source of shrinkage.
Why the seam decides the whole block
Every log carries the error from the log before it. A 2.5-inch strip sewn at a true quarter inch finishes at 2 inches. Sew it at a generous five sixteenths and it finishes at 1.875, and twelve logs later the block is an inch and a half small. This only works if your quarter-inch seam really is a quarter inch, and if you are going to be off, be off by the same amount on every seam.
Where log cabin blocks go wrong
The block turns into a parallelogram. That is the iron. Sliding it around stretches pieced seams. Press instead of ironing, and send every seam allowance away from the center so it tucks under the log you just added.
The center stops being centered. You changed rotation direction part way round. Pick clockwise or counter-clockwise on the first log and stay there.
Corners are not square. Check after every round, not at the end. Trimming a sixteenth off a corner now costs nothing. Finding out three rounds later that the block is out by half an inch means unpicking. Squaring up belongs in the rhythm of the block.
Blocks come out different sizes. Consistent strip width beats accurate strip width. Measure from the outer points of a pinked edge every time.
What happens to the blocks
Nine of these makes a baby quilt, and one on its own makes a table topper. Once the top is pieced, borders take it up a size without piecing more blocks, then basting holds the layers still. For the quilting itself you get two roads: straight lines with a walking foot, or free motion if you want texture that wanders. Binding closes the edge.
