So my newest machine (to me), I bought about a week ago. It's a Singer 15-91. It was manufactured around 1950 in Anderson, South Carolina. It's a special edition machine to commemorate 100 years of manufacturing. The blue badge says "A Century of Sewing Service 1851-1951".
My vintage machine dealer says that this is the best straight line sewing machine that's ever been manufactured. That's why I bought this machine. As you know, I've been sewing a lot of bags lately. I needed a machine that would sew multiple layers of different types of materials - specifically cork and pleather.
Where my 347 machine could sew through multiple layers of materials and make the bags I wanted, it protested greatly and I had to help with the hand crank during particularly thick seams, etc. My 15-91 - sews through all these layers like butter! She's a dream! She sewed through 8 layers of cork with no problem whatsoever.
I've named this machine Ora Bell, after my great grandmother on my mom's side.