Log cabin blocks are one of those that look deceptively simple. I mean it's just strips, right? I use the method where you cut your logs to size before you begin. This way you know if you're off as you add each one. I also press and square as I go.
Sounds like your blocks are all done and they aren't all the expected 15" finish. At this point, the only thing you can do is find the smallest one and cut them all down to that size. If there are just a couple that are a lot smaller than the rest, make new ones or unpick and re sew those. The problem with waiting until the end is if you have to trim, some of your outside logs will be narrower than the rest, however, hopefully not enough to be too noticeable.
Another tip for next time is: if possible, cut your strips along the length-wise grain of fabric. It stretches a lot less. Easy to do if you are starting with yardage, if you are using scraps or precuts, not so much...
Last edited by PaperPrincess; 04-03-2016 at 04:36 AM.