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!
Very nice quilting, Muv!! I would like to see the potholders too. I am learning FMQ on my 301a, which does a great job of it....it will go slow when I need to, or go faster when I feel confident enough to go fast. But when I took a class last weekend on background fillers fMQ, the teacher told us "fast is not necessarily good...you have to keep control of the stitching, or your FMQ will be garbage and you'll break thread and needles". So, there may be more advice in that statement than I could ever come up with. I don't go fast...I really kind of poke along, and it's working out for me.
BTW...there were gals in that class with $2,500 machiens who couldn't make them FMQ to save their lives!! Broken thread, bad tension, etc. etc. etc. My little 301a just kept going along, no problems for over 5 hours of FMQ class!! There's a lot to be said for "old and basic" when it comes to sewing. LOL