Nerf Rival Prototype Launcher

thingiverse

Update: This design is now obsolete, the new version is here: https://www.thingiverse.com/thing:3543902 This is a launcher designed to aid in future designing of a 3d printed nerf rival blaster. The arms are designed to pivot so that the proper "crush" can be determined. Wheel size can also be altered for different speeds. This is NOT a finished nerf blaster (though it does shoot well), only a testing rig to play with variables such as voltage, wheel size, crush, load, etc. Feel free to alter, modify, redesign, whatever you want. I am looking to design and build a pistol and/or carbine but needed some data first so this was born. I take no responsibility if you touch the wheels with your body while they are spinning. They will burn you, quickly. They have tremendous power stored in them. I am not an electronics expert, take my design at your own risk. This is not meant to run for extended lengths of time, just long enough to learn. Instructions: Some stl files may need rotated. I have also included autocad drawing (just what i like to use) in case you want to modify things. NUTS NEED TO BE SCALED between 107-110% in only X&Y or they will not fit. The threads are also left hand, and 90 degree included angle. These are not proper, but i didn't care for a test model. Most likely you will need to ream the holes for the motor shafts. I used a 5/64" drill and very carefully reamed the hole at a low speed. This creates a hole with a .0006" press fit. I do not know what metric drill to use, but the shafts are 2mm. You need to go a touch smaller. If you scale the flywheels, i recommend filling the hole somehow and recreating it. I may upload a wheel with a 1mm pilot that could be scaled up to 200% and reamed if it's requested. The flywheels came out rough for me, so i recommend sanding the outside to a 220 grit. Again, testing. I think this was just too many features in a small area and it just put out too much filament. Motors may slide after some vibration. I wrapped mine in a single layer of electrical tape before inserting. A flathead screwdriver can be twisted in the slot to open up the motor housing. You could also hot glue them or something. I hot glued down the slot after a while and it holds well. Final design will have mechanical retention. To shoot, plug it in and push the balls in from inside the hexagon aligner. There is no barrel. A magazine can also be held at the back and released with the walls. If there is any confusion, when viewed from above the wheels should spin so they pull a ball out of the hexagon holder. Going the other way will result in a jam and shredded ammo. There is no need for a barrel yet. Testing so far: -For spacing, i have roughly a 3/8" gap at the tightest spots on the wheels. Play around a bit and find what you like. -Torque is excellent. I have dumped an entire 12 round magazine through it and do not notice velocity depletion until after 6-8 balls, where it maintains ~70% from there on. Larger wheels could be needed for better speed, but sacrificing torque. Voltage could be increased to compensate. -Heat is manageable. The motors only become warm to the touch after ~2 minutes of no load with an instantaneous 12 round magazine dump at 1 minute in. Voltage could be swapped for amps to improve load capabilities. I'm no electrical engineer though. -Hop-up will need to be added for the blaster version. I am looking into ways to do this with the flywheels rather than a nub. What i used: Battery connectors https://www.amazon.com/gp/product/B00XQ91998/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 Battery (use whatever you want) https://www.amazon.com/keenstone-Butterfly-Nunchuck-Connector-Discharge/dp/B0132TPIBQ/ref=sr_1_4?keywords=airsoft+battery+9.6v&qid=1553209103&s=gateway&sr=8-4 Motors (5 pack) https://www.amazon.com/gp/product/B01M0XOOS5/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 Red filament https://www.amazon.com/gp/product/B00ME7424W/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 Silver filament https://www.amazon.com/gp/product/B00ME7YUIU/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1