Plastic Rubber Band Powered Crossbow

I was making fun print for my cousin and it turned out better than expected. I hope he. will still like it even though it doesn't have any fire involved like he asked for.

3D printer

filament

rubber band

string

toothpick

tinkercad

Design the barrel: make a cylinder that is 30mm by 30mm and 140mm tall. Make a hole all the way through that is 20mm by 21mm by 140mm. Line them up perfectly by highlighting them and pressing L. Group them. make a cube the same height as you will make your crossbow limbs. Make it at least the width of your barrel. make another cube and make it 18mm in width. and at least 40mm in length. turn it into a hole. Take the block you made before this last one and sign it up with the one you just made and group them. Turn this into a hole and pit it on the top so that it is the highest it can be while not being any higher than the barrel. Group it. Make another cube. Make it 10mm in width and however tall you made the barrel minus 20mm. sign it up with the barrel tight in the middle and 10mm off the ground. group the hole thing.

Design the limbs: make a cube 200mm in length 5mm in height and 30mm in width. make another cube 18mm in width 185mm in length and more than 5mm in height. center this with the over peace and group them. you can be done with the limbs here or you can arrange 2 wedges on either side in a funnel like shape.

Design the grip: Make a cube. make it 50mm in length 10mm in width and 20mm in height. make another cube and make it 6mm in width 20mm in length and over 30 in height. sign this up on one of the small sides in the middle of the bigger cube. turn it into a hole but don't group them. take a wedge make it the same width of the bigger cube make it 10 mm tall and 10mm long. group the contraption.

Design the trigger: take a cube make it 63 mm tall 5.5mm wide and 19 mm long. make another cube with the same dimensions except make the width 8mm and make the height 5mm. Sign this up to the bottom of the other cube. Take a wedge and make it 8mm wide 10mm tall and 19mm long. make another cube make it 11mm long more than 8mm wide and more than 80mm tall. Line it up to one side and however make it however high off the ground that you want to take off the trigger. This is to let your hand sit more comfortably.

Design the piston. take a cylinder. make it 19mm by 19mm by 30mm tall. take 2 cubes and make them 5mm tall and 5mm wide. arrange them so there is a least 3mm of space between them and the top and bottom. Make both holes and group the whole thing.

Design the ammunition: Take a cylinder and a paraboloid. put the paraboloid on top of the cylinder and group them. make them 19mm wide 19mm long and 40mm tall.

I have included the stl so you can check your work with mine.

Put your print into a slicer like normal. The settings I used were 60% infill and 0.4mm nozzle. Export to your printer and print. It took me 13 hours to print. I'd recommend printing it overnight.

Take the piston and thread the rubber band through one of the holes. Thread a piece of string through the other and make it a loop. take the two ends of the rubber band and wrap them around each end of the limbs. Fasten them by using a tourniquet type thing using two toothpicks. trim the sharp ends off and your almost done. Take the grip and trigger. super glue the grip to the back of the crossbow so the triangle is not touching the body of the bow. after the glue dries take a bullet and put it in the barrel. Use the trigger to push the bullet down until you can grab the loop of string and hook it over the triangle part of the grip. Put the trigger back in its place in the handle. pull the trigger to push the loop off the triangle allowing the rubber band to snap back propelling the bullet.