Like Janey said, you have a Singer 15, in a Singer treadle, and the estimate of the 1950's is what I'd go for also.
I have one very similar, with an electric motor on the back. I'll share a picture when I get my camera recharged.
If you want to do some research - Standard was bought by Osann, and they had a lot of industrial machines. Singer bought Osann, and in the process also acquired the patents and names Osann had from Standard. So you won't find anything about Singer buying Standard because Osann was in the middle. Though your machine does not really have anything to do with that other than the name.
If you look at pictures of the Hexagon machine made by Standard (it's a vibrating shuttle machine) you'll see that some of them have the exact same decal pattern as yours. Singer was very good at using up "leftovers" when they bought out other companies.n It's very neat to see one of those "in between" machines.
Last edited by Macybaby; 07-04-2021 at 03:20 AM.