Originally Posted by
QM
You will need to calculate the exact perimeter, precut and connect the 2 ends of the binding before you add it (pressing the seam open). Be sure everything is starched or sized and pressed. Why are you binding something this size? If you are making something like a pot holder, you might be happier finishing it 'pillowcase' (or 'birthing') style.
Circles that small are very very difficult to get right as there is a big difference in the inside seam and outside seam distances and therefore how much extra the bias needs to stretch round the corners.if it isn't lying flat it is because you have too little fabric around the very outside edge. I would actually not startch the bias too much you need the flexibility. the trick is to push the bias under the machine a little more as you sew the first line down and clip the curve of the bias tape to allow it to spread. it needs to NOT be stretched out and as full as you can get without it puckering. The tape after the first seam will be all wavy and flouncy and that is right.This means when you turn it to the other side there is enough fabric to stretch around the slightly longer perimiter of the piece. you will then have to ease in the second side. I usually stitch this by hand as it is easier to get the fullnes taken in.
However I do wholehearteted agree that if they are just 4" circles a birthing technique will be far faster easier and give a better overal finish.