Macybaby

looks like a nice Model 27. Being it's a Singer ruffler, your chances are better. Since the 27 is an older model, it's harder to know. Singer made significant changes to the ruffler during the time the 27 was in production. By about 1920 the ruffler style was about where it is today. it's also very possible that your grandmother got an updated ruffler for her machine at some time as they had more options and worked better.

I think I have around 15 different styles of Singer rufflers.

These are the four that were used in the Puzzle Boxes.

The ruffler sitting on top of this case is from about 1940 - and very similar to what modern ones look like.