Thank you all very much for your support and suggestions. I love the 3 foot rule!
I have made some test squares, and tried different methods of quilting with them. Next I am going to throw them in the laundry and see what happens. They are all made from left-over scraps of the quilt materials. I tried free motion using the Singer 15-91 with a darning foot, and then realized I can’t move that machine to the Senior Center where I can use the big tables to support the work. I used "invisible thread" on this square (with orange blocks in the corners), but I'm not so sure I like the results. I'll look at it again after I wash them. So I tried different methods using portable machines.
The Singer 66 doesn’t have a way to lower the feed dogs, but a plate is available that covers the feed dogs. This doesn’t work with the ruler templates though because it raises the templates due to the hump over the cover makes.
I finally found how to lower the feed dogs with the Singer 301. They hide that info in the very back of the manual under darning! That machine works pretty well for stitching in the ditch using a walking foot, and it’s throat is as big as the 66 or 15-91. I think I am going to try sewing the big quilt on the diagonals using this machine. It’s easy to carry too. Interestingly it’s this machine that brought me to quilting and this website. I heard that quilters love them, and now I know why!
Thank you all for your comments and moral support! I’ll come back and let you know how it went.
Joe