The bottom fabric feeds more then the top fabric because it is next to the feed dogs.To counter-act this,hold your fabric like you normally would,But,tilt your hand toward the machine.You are forcing the top fabric to feed a little more then the bottom fabric.This takes a little practice but it works.Practice on 2 very long pieces of fabric.It takes a time to learn.

Or use a walking foot, which would feed both top and bottom evenly.

I like the idea of drapery weights - smacked my forehead and thought "Why didn't I think of that?" lol

I just looked at my new drapes and curtains. They used the finest threat I have ever seen. Also very loose sewing. It appears to be blind stitch. Good luck. They also have several drapery weights.

Depending on the weight of the fabric your hem may need to be wider to get it to lay properly.

Let us know what you end up doing and how they turn out eventually.

I had a similar problems with curtains I made for a friend years ago. Later learned that I should sew the sides and then measure the length before putting the heading on the curtain. It did work out for me with other drapes I made. Couldn't tell you why, but it did. Good luck with your problem.

I use to make drapes for people. I went to classes to learn how and the FIRST thing you do after measurement, is the hem. Yes that is what I said. (the hem should be double) You hem, then lay out the the hemmed panel and press the side hems in and sew. Then you lay out and measure from the bottom to the top and press the top banding over to your measure ment. Will hang perfectly straight when you put on rod.

I forgot to say one important thing--the hems are put in by hand. Machine prevents hem from hanging straight. I know, ladies you don't like to hand sew but some times it's the only way to do it professional for the best look. Any drapes that are special order will be hand sewn on the bottom. Try it. I guantee you will be pleased.

When you order custom made drapes from an interior decorator the hems are usually put in by hand. That will eliminate this problem.