jshep
I know I'm a year late, but I have a different opinion than the others. I also have a Pfaff 6 and the manual says it will do canvas, leather, and sacking with a 110 needle and mercerized cotton thread (40). The manual explains how to take the top off and adjust the needle drive for heavier use. The shuttle also has a tension set screw to increase tension as does the thread feed on the front of machine. If you adjust all this and get a 110 needle with heavier thread, then you can do some leather work just fine. You can get the manual for under $6 online and it will explain all this with pictures.
Pfaff 6 manual (link below) indicated that this straight stitch machine was made with high grade components for industrial use. Do not let anyone tell you that it's too cute to do serious sowing. Granted, it's got limitations, but it's a great machine. We've had ours for 20 years and it's never let us down. In fact, we loved this old machine so much, that I bought a $3000 Pfaff expression quilters model and have had that for 17 years. Absolutely love our two Pfaff machines.
I also bought a leather patcher from china for $100 because my Pfaff machines are not going to do rubber or shoe leather, of course.
https://manualsoncd.com/product/pfaff-6-sewing-machine-instruction-manual/
