Since I wrote about buttonholers awhile back, I have learned some new things about them. Here is a quick link to the original post http://vintagesewingroom.freshwaterfibers.com/2015/11/which-buttonhole-attachment-fits-my.html
Most of what I have learned lately is about buttonhole attachments for zig zag sewing machines. Of course you can use the straight stitch attachments on your zig zag sewing machine, but it doesn't go the other way. The zig zag buttonhole attachments use the zig zag stitch on your machine to make the buttonhole, rather than moving the fabric back and forth to make the stitch for the buttonhole.
I got to try this out, with a Griest 1Z buttonholer on a Singer 237, and it made a sweet buttonhole. I am planning to put this machine into a treadle cabinet, and it will be great to have a machine I can treadle that zig zags and does buttonholes.
So Griest made seven different buttonhole attachments for zig zag machines, they are listed on the box I photographed in the earlier post.
Singer is the big player in the vintage machine world, and they made their version for zig zag machines in the 1960s when they brought out the Professional Buttonholer. This comes in a model for slant shank zig zag machines, and for vertical needle machines (low shank). This is the first time there are different plates for covering the feed dogs according to the type of machine you have.
Charlene Phillips wrote a great article for ISMACS http://ismacs.net/singer_sewing_machine_company/more-on-singer-buttonholers.html
So you have options. You can use a straight stitch buttonholer on your zig zag machine by setting it to straight stitch, of course you have to match up Shank type and needle position. All of the Singer buttonholers up to and including the Jetson's case ones are for straight stitch machines (or zig zag machines with the needle set to straight stitching). But the Singer Professional, and the Griest models with a Z on the end are for zig zag machines.
Hope this helps someone, it took me a bit to sort it out. That's what happens when I get most of my sewing goodies from a thrift store!