How to make a spring crossbow

Spring crossbow

Difficulty: ★★★★☆

Time: Couple of days

From scrap: ████░░░░░░ 40%

Preamble

Could you imagine crossbow without bow? Such crossbow uses an energy of expanded spring. So here is a my story about how to build a spring crossbow.

Materials

• A powerful springs
  
• Steel pipes
  
• Metal parts
  
• Planks
  
• Plywood
  
• Bearings
  
• The steel axle
  
• Sheet metal

Tools

• Hacksaw
  
• A set of mounting tools
  
• Drill
  
• Emery
  
• Glue
  
• Files

Design of spring crossbow



• Springs

  
  In this diy crossbow I used an energy of two 15-kilogramm springs
  

  


• Tubes

  
  Springs placed into two tubes, connected with metal plate
  

  

  
  

  


• Trigger

  
  Trigger system is complex: all force is in a part which connects tubes. Secon trigger system is for bowspring
  

  After pulling the trigger tube connector will free, and after short delay release a bowstring


• Sheme

  
  

  Scheme of diy spring crossbow

  
  

  


• Preassembled

  
  

  

  
  

  

  
  

  

  
  

  

  
  

  

  
  

  

  
  

  

  
  

  


• Body

  
  I made a body of wooden board
  

  

  
  

  

  
  

  

  
  

  

  
  

  


• Pulleys

  
  I made plywood plates and fastened them into forward part of crossbow
  

  

  
  

  

  
  

  


• Bearing

  
  Plywood plates serves as decoration and as mount for bearings for pulleys
  

  


• String brake

  
  Also I mounted bowstring brake on them
  

  


• Buttstock

  
  For usability I made a buttstock
  

  

  
  

  


• Clamp

  
  Also I made a clamp for ease reloading of spring crossbow
  

  


• Bolt press

  
  

  

  
  

  


• Pulleys

  
  

  


• Result

  
  

  

  
  Author: deminpetr74

Video

This is not the only design of spring crossbow. The author of the following video insists that his spring crossbow has tension force of 1800 lbs!!!

Results and tips

• Crossbow turned out interesting, but quite weak.
  
• The tension on the string 15 kilograms.
  
• Arrow weighing 30 grams flying straight at fifty meters.
  
• I think I need to replace the springs with more powerful air springs, they also has less inertia.

Tags: crossbow