Nerf Crossbow

thingiverse

https://www.youtube.com/watch?v=YuyjK7GAs_g This was designed from, and shares a lot of pieces in common with the modular crossbow/slingbow project. Careful attention must be paid to slicing these .stl files in prusaslicer to get the best results. Several .ini files have been included. The recurve arms are the most difficult part,the aim is to get these on the edge of over-extruding but not so much that the blob up or otherwise fail. The larger trigger pieces should be printed with as many perimeters as possible, and 100% (or close to 100%) infill to maximize strength. All the parts should be printable without support in the proper orientation. Some that have tended to curl up or lift of the print bed have some partial rafts added that should be removed after printing. Print Settings Files (0.4mm nozzle only) 0.25mm_STANDARD_PETG.ini - For most parts. Layer height can be adjusted if more detail is wanted. 0.25mm_SOLID_WIDE_PETG.ini - For the recurve arms only. Intentionally overextruded, I had no problem printing with these, but watch the printer closely while printing to ensure it does not blob up or otherwise fail. PETG_0.92e_240C_1.75mm_FAN.ini - Generic PETG for most parts. Temperature, etc. parameters can be tuned to specific type of PETG. PETG_1.00e_240C_1.75mm.ini, PETG_1.05e_240C_1.75mm.ini, PETG_1.10e_240C_1.75mm.ini - For the recurve arms only. I started with 1.05e, and increased to 1.10e if under-extruding, or decreased to 1.00e if over-extruding. Full assembly video: https://www.youtube.com/watch?v=lI8SPmZvMAY Before assembly, the two trigger parts must be glued. trigger_rear_base.stl (small piece) to trigger_rear_main.stl (large piece) trigger_lever_platform.stl (small piece) to trigger_lever_main.stl (large piece) When gluing the lever piece, it is critical that the platform is pressed all the way down and forms a right angle with the main piece. A guide is provided, "guide_glue_trigger.stl", which can be printed with PLA using the draft PLA profile "0.25mm_1P_PLA.ini" (single perimeter, 3 solid infill above/below, 5% infill) in order to minimize printing time and filament use. Prior to assembly, apply a lubricant generously to the trigger parts. I use "Super Lube 51030 Synthetic Oil with PTFE, High Viscosity, 1 quart Bottle, Translucent White" https://www.amazon.com/gp/product/B0025PR4K2 but any oil (or grease) that is compatible with plastic should work fine. Two springs are used in this "V1" design, the first is a 20mm compression spring used in the bed of common 3D printers like the ender 3 https://www.amazon.com/gp/product/B07V6YCYP5 the weakest one in the kit. The second is a common 23/64" x 1 3/8" spring contained in any number of spring kits: https://www.amazon.com/gp/product/B000K7M36W https://www.amazon.com/gp/product/B0002KO1X0 Note this is a recurve crossbow so when in the rest position the crossbow arms will angle forward, or away from the user. The string should be kept slightly less than taut while in this rest position. To ready the device, pull the string back over the sight and drop it down where it will be held in place by the front body. When readied, the arms will be bent at a backward angle resembling a typical bow-and-arrow. When the device is not in use, especially for an extended period of time, return the string the rest position to preserve the integrity of the plastic arms. This particular device has not been tested with non-PETG arms but I have found some hybrid PLA+ or mixed PLA/PHA filaments have worked okay with other similar devices, however the lifetime is typically limited to around a hundred shots, after which broken arms can be a common failure mode.