I want to shorten a few pairs of my daughters’ pants to make them shorts or capris. The pants are cotton with a bit of stretch (95% cotton, 5% spandex).
My main question is, do I stretch the hem as much as possible while I’m sewing with my crappy old Singer, or do I stretch it just a little bit, or do I not stretch it at all? Also, do I need special thread?
She and I don’t really care how they look (she’s only 2 1/2) as long as the hem will hold together throughout the summer.
You have to stretch it a little bit - I think this will be as hard to explain in writing as knitting tension, there’s a lot to how it feels. Enought to smoothe it out but not enough to change its shape. If you stretch it too much your hem will pucker up when you release it. Not enough the hem stitches will break when the fabric stretches during normal wear.
You should make the stitches pretty short.
Could you make a practice hem on the portion you cut off just to get the feel?
Thanks … a practice hem is probably a good idea. It’s just that I don’t know how to re-fill my bobbin, and I know there’s a bit of thread in there that will work - and I don’t want to waste it! 
Filling your bobbin ought to be pretty simple. Have you got the manual? If not, what kind of machine is it? There ought to be a little bobbin-filling mechanism on the top right, or maybe the front of the machine. I bet we can figure it out!
Thanks dangermom - I will give it a whirl and find you if I (or the bobbin, or the thread) get totally stuck!
You’re probably already planning to do this, but a reminder to pin up the hem all the way around. This will help prevent pulling too much.