Birdpath

Hi folks: I know the Singer 20U is undersized for leather work. I am trying to set up a binder and need some help. The machine has the usual two holes in the bed for attaching binders. However, the usual knurled screws that some with binders are not the right size. They fit my other machines (e.g. Juki) but not my singer 20U. Does anyone know what screw/thread size these holes are tapped for? Many thanks for any help, Daniel