Release mechanism for cord

thingiverse

Hi, I had the idea to this while i was ill on a weekend and had nothing to do. I stumbled uppon a video of an really old slingshot release mechanism out of germany. I thought that i could make this more compact and usable for a model crossbow, with the advantage that you can easily activate the trigger no matter under how much force is put on the cord that is hold by the mechanism. After three days workig on it the first prototype was functional. After a bit finetuning on the modely everything worked perfectly. I tested how much force it holds when its printed from Pla and it was over 50kg with 50% infill (slipped through at 65kg) and probably over 75kg with 100% infill (wasn't able to measure it completely yet). To make it work properly i had to use a file on a few places of the part because my 3D printer is really bad and had oscillations while printing. With a better printer i wouldn't have had to do this. In addition to the printed parts you need: - two springs with about 4.5mm diameter (ones from a ballpoint pen worked for me) to bring the trigger and the angle barrier in a defined position after triggering - some glue or something else to fixate the springs and one side of the axis into position (i used uv curing glue or uv curing resin) - 3 nails with 3mm diameter as axis for the moving parts that you have to cut to length (as long as the assembled part is wide so it doesn't stick out) - a few m3 screws to screw it together. If you don't find two springs you can also use just one spring from a ballpoint pen but you have to cut it in half and stretch it a bit. When you install this in a narrow space where you can't have screws in it while installing you can put shortened nails through some of the spare holes to hold the parts in place until it's installed where you wanted to install it so you can fixate it with some screws. Have fun building! I am happy about any feedback.