Well
Leather is measured in 1/64 of inches. 1/64 inch == 1 ounce, basically. So a 1/4 inch screw would be 16/64 or hold 2x 8 ounce pieces together. You might be able to stretch that a bit.
So get a few more sizes, that will make you happier, like 1/2" and even 3/4".