I recently acquired a Singer 670G Golden Panoramic Touch & Sew vintage sewing machine (quite a mouthful). Apart from being a very sturdy and strong all-metal machine (no plastic gears!), another fascinating thing about this machine is that it uses so called Special Discs to create advanced stitch patterns. The discs themselves are really simple and I immediately thought of printing some. Not wanting to reinvent the wheel I googled around a bit and ended up on Leila's blog Grow Your Own Clothes, https://growyourownclothes.com/2017/10/11/3-step-zig-zag-disc-for-singer-slant-machines/ She graciously shared her basic template and that inspired me to make my own version anyway, in OpenSCAD for easier experimenting.

Stitch patterns are created by editing a few lines like shown below, where the needle position is the "1". Each disc has 24 positions so patterns has to line up with that to repeat properly.

// Overedge stitch, stretch overcast_zz_short = [ "1........", // 1 "..1......", // 2 "1........", // 3 "..1......", // 4 "1........", // 5 "........1", // 6 "1........", // 7 "..1......", // 8 "1........", // 9 "..1......", // 10 "1........", // 11 "........1", // 12 "1........", // 13 "..1......", // 14 "1........", // 15 "..1......", // 16 "1........", // 17 "........1", // 18 "1........", // 19 "..1......", // 20 "1........", // 21 "..1......", // 22 "1........", // 23 "........1", // 24 "Overcast", // Name "zz short", // Name line 2 4 // Number of steps to rotate pattern ];

Bottom and top finish are not important since the needle position follower only touches the edge.

These discs should work in 400, 500, 600 and 700 series machines, but always try slowly with the hand wheel first. Feel free to experiment with your own patterns, but please post them here for other to use.