Parametric shock cord winder for model rocketry

thingiverse

This is a shock cord winder for use in high-power rockets. This will allow you to pack your chute and shock cord as a series of "pucks" which fit very efficiently into your rocket. Good thing if you are tight on space! This has two pieces, the knurled base with the winding post and the outer housing to keep everything nice and neat. This is designed for a 4" diameter rocket and 3/8" wide shock cord, although it will work down to 2" and up to about 1/2" wide shock cord. I've included .stl files for that size if you don't want to mess with the customizer. I haven't tested this on larger or smaller values, but it should work nicely for anything from about 2-6". The main parametric settings are winder diameter, which is the inner diameter of your rocket, your shock cord width, and shock cord thickness. The "tolerance" value gives you some wiggle room to fit the post into the center hole of the housing. For my printer and PETG, 0.3mm works great but you may need to adjust that upward if it doesn't fit properly. Print the housing at 20% infill, and the knurled base at 40%. This is roughly based on the strap winder at https://www.thingiverse.com/thing:3502166, but I wrote the code from scratch so I could customize it.