I could show you but don't know how to write it in words. It's a matter of changing the angle from 90 deg to 45 deg. I don't know of a machine procedure, I'd have to do it by hand. Sorry I'm not more help.

Your binding must be bias binding. Fold it and use Elmer's glue (ironed dry) to keep it in position after you sew it to the topper.
On table toppers and placemats I like to use single binding it's easier to work with IMO.
Rosa

I dont use bias binding,but you can do either. Here is a little chart that may be helpful.

Thanks a million. That's what I needed. It proves , "A Picture is worth a thousand words."

Caroline thanks so much for the "picture". After looking at it, it makes so much sense but it sure makes it easier to "see" first.

I love all the octagon projects you've done. Thanks to agnesd for asking the question as well.

Susan