Slippers with 3D Printed Sole

Finding decent quality slippers for kids isn’t easy these days, so I decided to try and make a pair. The process seemed quite simple, so I figured out what to do as I went along. I looked at some patterns for slippers, but ended up making my own according to the measures and traced shape of my daughter’s foot. She picked the fabric that would go well with blue TPU I would print the soles with. Once I had my pattern created in Illustrator, I brought the sole outline into Maya, and it contained both the original path and the path that was offset by a quarter inch for seam allowance. This larger shape was kept as a beveled object, with bevel width set to zero, and I converted an edgeloop of inner shape into CV curve, and used that as motion path for the cylinder, which I duplicated along this curve with animation snapshot command. Then, I used boolean subtraction to punch these cylindrical holes out of the main sole shape, and also created a rail that is a bit wider than these holes and goes halfway through the thickness of the sole, and that was subtracted to serve as a channel for the stitches, so that they wouldn’t wear off during use. I also added beveled circle pattern to give a bit of the relief to the sole, and cut the channel out of that too. The print was 4mm tall (that’s 20 layers of 0.2mm) and it took over 16 hours to complete. This is because TPU prints at lower speeds than PLA, with infill being printed at the speed of 30mm/s, while walls are printed at only 15mm/s.

The sewing was pretty straight forward: the top part is a sandwich of printed cotton, fusible fleece and solid color cotton, while the bottom part is without the solid color. The binding strip was then stitched onto top parts, just like a quilt, except that I haven’t done any quilting – it just didn’t seem necessary. The top and bottom parts were sewn together with the binding strip. Then, all that was left to do was to stitch the 3D printed sole to the rest of the slipper. I originally intended to make the stitch visible all around the top of the slipper, but since I was doing this by hand with a crochet thread, the stitches didn’t look even as they would on factory made shoes, so I decided to stitch the sole to the bottom of the binding strip and not have it visible on top. Finally, to tie it all together, I put the E6000 glue all around the perimeter of the sole, to close the gap between binding strip and sole, and it was held together with bunch of clips for two days and seems to be glued well. Clearly, there are some imperfections, especially on the right slipper where the binding strip didn’t quite cover the sole all the way around, but for the first attempt at making footwear this turned out pretty well, and my daughter likes them, which is all that matters. If they get worn a lot, I’ll update this post showing how well they held up.

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