Vintagemotif is right, Singer 15s are great fun. Here is the first FMQ I have done on a quilt, and I used my 15K treadle. I did the first try out on a Friday, did three big practice pieces over the weekend, each big enough to cut up to make six potholders, then did the first little quilt on the Tuesday.
FMQ on a treadle is hot work - you really have to keep the speed up!
You did that on a treadle?? I'm impressed!! Great job!!