Saturday, September 22, 2018

Simple K'nex Launcher - Lesson 1

Hey, all. If you're already a veteran launcher builder, forgive me as I'm focusing on new builders today. And if you are a new builder, grand, glad to have you here! This is both a guide and a set of instructions. Guides and instructions will be appropriately labeled. If you're interested in learning how to build launchers, I suggest you filter by the "guide" label and follow them in order from oldest to newest. I'll show you how easy it is to jump in and work your way up to more complicated builds.

Today's build is based off a launcher I saw on YouTube when I first started building. I honestly don't remember the creator or where this video is now, so if anyone knows, do let me know so I can properly credit them. I take no credit for this design. We're going to dive right in and get right to building. Afterwards, I'll explain some of the basics to help you understand the fundamentals of projectile launchers.

Instructions:

Parts List:

  • 3 blue rods
  • 1 white rod
  • 4 two-slot angled connectors
  • 2 single-slot connectors
  • 1 two-slot straight connectors
  • 1 rubber band (I recommend getting a bunch of #64s, but any will do)
  • (optional) 2 "Y" connectors

Steps - Building:

In the future, I will break steps up and have more thorough descriptions, but this build should be easy enough I'm just going to trust that you can follow along with the pictures. I will label the individual components for referencing later. Just to note, this is designed primarily for right-handed people. If you're left-handed, mirror the steps to build a left-handed version.


Striker

Striker Guide

Sear + trigger

Chamber

Projectile lock

Chamber

Structural support

Thumb rests - Since these parts aren't as common, it's OK if you don't have them, they just make it easier to grip

Insert the striker

Thread the rubber band through

Wrap the rubber band around to the bottom two blue rods on each side. Make sure it goes over the straight connector like so, it should be putting tension on it

Firing:

Congratulations on finishing your first launcher! It's that simple. Now, before we get to firing it, here's an obligatory warning not to point this at anything you don't intend to shoot, living things especially, even if it's not currently loaded. I don't assume any responsibility for any damage you may cause. 
Pull back the striker carefully so as not to pull it out of the back. If the band is setup right, the sear should automatically block the striker.

Carefully load a white rod into the barrel

Grip your finger around the trigger

Put your thumb against the side, resting on the "Y" connectors if you have them. Squeeze your thumb down and your finger in to rotate the sear out of the way and fire.

Terminology:

Alright, I hope you're excited to already have your first launcher built. If you're content to follow instructions, that's as far as you need to go. But if you want to build your own launchers in time, then I suggest you learn some of these concepts so you can figure out how to apply them yourself.
  • Striker - This is named so because it strikes the projectile to launch it, and it's one of the simplest and most common ways to launch a projectile with K'nex. Fundamentally, it's just a rod, a connector, (on stronger launchers) shock absorption, and rubber bands to give it energy, and then it's held back by some sort of sear. Note, you may hear others refer to it as a "firing pin" or "bolt" but those terms aren't quite accurate. 
  • Striker guide - This is simply a section of the launcher that guides the striker. Will discuss this in greater detail in future posts. For this launcher, we used one of the simplest methods of putting connectors together so their holes form a tube to contain the striker.
  • Sear - The sear is the part that holds the striker back. This can be done from either the front or the back of the striker, but typically it's done from the front by blocking the rod. 
  • Trigger - This is the part that you pull to disengage the sear. In the case of this gun, they're the same piece, you directly rotate the sear out of the way. Others refer to this as a "block trigger" and it's the simplest way to make a striker-based launcher, but not very ergonomic. Part of the challenge of a builder is making a good trigger-sear combination that is both strong enough to reliably keep the gun cocked but comfortable enough to pull to fire. We won't be using block triggers long, but they suffice for now.
  • Chamber - This is where the projectile is held. The action of loading a projectile is called "chambering" and there are different methods we'll cover in the future. This is a muzzle-loader, like ye olde muskets, where you stick it in directly in front. Like the striker guide, one of the simplest ways to make one for launching rods is to put a bunch of connectors together to form their holes into a tube.
  • Projectile lock - Finally, this is a slightly more advanced concept but it's worth mentioning; for a muzzle-loading launcher, the projectile could just fall out the front if we didn't have a way to secure it in the chamber. In the case of this launcher, the single-slot connector is slightly misaligned with the two-slot connectors, causing just enough friction to hold the projectile in. This works for now given how small this build is, but we'll come up with better ways in the future.
That's it for now. I hope you're motivated to come back and see what else you can learn to build. 

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