Saturday, September 29, 2018

SYCAMORE Semi-auto launcher

Sorry, already falling behind. I mean to get another guide post up but I've wanted to design the perfect launcher to go with the guide. So for today I'm going over another silly bit of my history.

If I haven't already mentioned it, I was a bit of a pistol guy. Even after the sidearm craze ended, I still liked making smaller builds because my pieces were limited and I enjoyed the challenge of cramming as much functionality as I could into little designs. One such design was the SYCAMORE:

Forgive me, I never did get my own picture, of this. "Travw" kindly got some for me on Instructables. Bonus, I dug up one of my old videos for it. It'd be embarrassing if it wasn't also slightly amusing to look back on. I guess for a little backstory, this is worthy of its own post, so perhaps I'll make one, but the concept of a semi-automatic launcher is inherently challenging because in order to fire shots in succession, you need to store potential energy for each shot, which is hard to do with K'nex. Basically, it was a challenge that I viewed separating good builders from not-so-good builders, and I had yet to build one until then. My method involved using the flex in the pieces and torque to have a mechanical advantage. I noticed that if you try to snap off a blue connector from a rod, it would actually fly a good distance. So I simply set a row up on a rod, added a spring to make a magazine, and then made the trigger unclip them one at a time. Boom, semi-auto. It was beautifully simple, and I was pleased, though it was otherwise such an unimpressive design.

I've thought about rebuilding it, improving the design, make it not require a spring, and then posting instructions. We'll see.

Wednesday, September 26, 2018

Mini repeaters

Today we have a fun, shorter history lesson. This was a brief competition a few of us builders had because I was "compettitive" (petty + competitive). If you read up on my TDS series, then you're familiar with the Mini-TDS. It was just for fun and remained uncontested (as far as I know) the smallest repeater for a while.

The above picture was actually a slightly improved version. I made it after someone else had designed a more compact repeater called the OKP. Unfortunately, the original instructions and pictures are gone, but someone else mostly copied the design and scaled it up a little.

The OKP was the new smallest repeater, and though I improved my Mini-TDS, it still wasn't smaller, and I just couldn't let that remain the case for long, so I set out to make an even smaller repeater.

El Mosquito was caught in an awkward spot of not remaining the smallest repeater for long, nor was it really functional enough to recommend building, but still I left up its instructions just in case. It was solely designed to edge out the OKP, because I'm competitive like that. That said, the OKP was a more functional design more worth building. I vaguely recall some other competition from something called "The Tick" by "Big Z" on Instructables.

Now we were getting into bragging rights territory. These things started barely working, just spitting out pieces in a pathetic attempt to be deemed a launcher. That said, he did technically succeed in making something even smaller. I think I was already working on my own design at the time that just barely won out dimensionally.

Behold the "Nano". I was actually quite pleased with this launcher and will still rebuild it to this day. It's still pathetic, but it works. Rest assured, even smaller "launchers" were built that were difficult to hold and loaded only one more projectile from the "magazine". Because, again, I was petty, I'd argue about the validity of calling them repeaters or how they didn't really have handles. Simple fact of the matter is that they beat me, but I was content with the Nano for still remaining surprisingly usable. And after that we never really cared about mini repeaters again.

Tuesday, September 25, 2018

Sidearms and the TDS series

Moving onto some of my early contributions, really the only noteworthy one was of my TDS series. Note: I'll include links for instructions, and while most of them are fairly simple, they'll use some concepts we haven't gone over yet if you're following the guide series, and they're not exactly great examples of what should be built either, so I'd recommend not building them. I'm mostly going over these just for a bit of history.

When I was a new builder, my main obsession was trying to replicate realistic firearms. At some point I wanted to try doing the Halo SMG. For reference, here's what a Halo SMG looks like:
Now, it had several challenges, but the ones I focused on at first were the shape and angle of the handles. Up until then, we rarely had realistically angled handles on our launchers, usually either straight up and down or at a 45-degree angle. So I came up with a way to angle both handles at a less extreme angle. I also tried coming up with a comfortably and somewhat accurately shaped handle.

Rest assured it was not good and I wasn't pleased with it. However, I did like the handle portion. I liked the idea of pistols with handle magazines, something to have as a sidearm in a hypothetical K'nex battle, but the only decent repeating ones were bulky and/or uncomfortable in my opinion. Probably the best one at the time was by DSman:

However, I found his rather long, and the handle uncomfortable, but it was basically the bar to beat, my competition. I saw an opportunity to finally contribute something to the community. I would simplify things to come up with the first version of the TDS, or TheDunkis's Sidearm.

Aside from its compact design, it had a removable magazine follower to make reloading a little easier. While it didn't get great range due to its design, having a nicely slanted handle magazine caused a lot of people to copy the general design to make their own sidearms. It started a friendly rivalry with DSman. I made many variations of the design, including one where I was prototyping a slide. I didn't really care for the bulkiness of this design. It was mostly just to prove I could do it.

Another variation I made was a mini version, which was the smallest repeater at the time.

My obsession with sidearms continued as I tried to come up with the "perfect" sidearm. I believe my standards, while doable today, were pretty high at the time, such as wanting a removable magazine and slide-action. One of my failed experiments was trying to make a removable magazine. The handle connection was flimsy and I never actually made the magazines functional. 

Needing help, I tried collaborated with DSman from above. We couldn't come up with a shared design and ended up both trying to improve our original designs. This lead to the TDS2, which was basically just a couple improvements and mostly aesthetic changes since I couldn't make any breakthroughs.

I overhyped it for being something not all that much better than the original, but it was still relatively popular for the time. I wasn't really sure how I could improve the design much more at the time. So I moved on from my fascination with sidearms for a while until saw a new design that incorporated a slide and was otherwise not inspired by my TDS series, which made it novel. I took the slide concept and went through a few prototypes until I was content enough to post the TDSS (TheDunkis's Slide-action Sidearm).

It didn't work all that great since I focused more on the slide than anything else, but I did like how it looked. But the time for sidearms had passed, we were into newer, better things and this didn't reach the same level of praise as my previous pistols, so this is where the series ended. I still considered the TDS2 the best sidearm of its kind, of course in bias, and a slide-action couldn't improve performance more than it could hinder it. Still, sometimes I wish I could've improved the design of the TDSS to be something more functional even if it were to remain just a novelty. It is worth noting that there was a resurgence in handle magazine pistols when people started trying to replicate real pistols, but they were never intended to be sidearms.

So that's the gist of my TDS series. Between the TDS2 and TDSS I'd do a few more things before my next obsession became Assault Pistols, which we'll cover in another post. Did you ever make your own or someone else's sidearm? Let me know in the comments. 

Monday, September 24, 2018

Basics of power - Lesson 2

Today I'd like to get one of the other most fundamental aspects of projectile launching out of the way: power. How do we maximize the range at which we can throw projectiles? This will be a common goal for many builds, even if it's not perhaps a primary goal.

Today, our case study will be a famous pistol by a well-known veteran launcher builder Killerk, who now goes by Knex Lego Maniac on Instructables. Maybe we can go over more about him in a future "meet a builder" post, but back to his pistol. It was one of his first contributions and one of the most important to date. While old, its concepts are still relevant. Here are his instructions (note, you will be directed to I believe they should be easy enough for you to follow. His pistol expands on what we've already learned and adds a few new concepts that I'll go over below.


  • Striker lock - The tan peg connector at the back of the striker guide acts as a way to prevent the striker from being pulled out the back of the launcher on accident. It adds friction, but it can be well worth the trade-off to make it easier to recharge. 

Concepts - Maximizing range:

For striker-based launchers, these are the five main concepts for maximizing range.
  • Striker length - In general, the longer your striker has to travel, the more time it can build up speed and launch the projectile farther. So, in general, it's good to have a longer striker. Mostly commonly, you'll see a black/clear rod used. These colors use a less flexible material so the striker is less prone to bending when we stack on extra bands.
  • Striker guide length - This is always a trade off. In maximizing the distance the striker has to accelerate, you should have less dead space at the back of the launcher for guiding the striker. However, it's important to have enough to support the guide. The above pistol has a relatively long striker guide. Most modern builds will have about 2-3 connectors or a similar length to that.
  • Projectile lock - We learned in the last guide what these do, but they're also important for the range of a launcher. You don't want it to cause too much friction, and you want it to hold the projectile at the very end of the striker's range of travel to maximize the speed. On the above launcher, the ball socket connector acts as the projectile lock.
  • Friction - In general, we also want to avoid friction, anything that the striker or projectile comes into contact with. As such, you'll notice that many launchers don't have real barrels other than the chamber where the projectile is held. Barrels only serve to reduce the max range and don't really add any accuracy. So you'll notice that at the bottom of the instructions for the above launcher, he redesigned it to actually minimize the amount of connectors around the striker. 
  • Shock absorption - Finally, the striker is still made of relatively loosely connected plastic. It can only handle so much abuse before pieces fly off or perhaps even break. So, in order to stack on more rubber bands, you'll need to make sure the shock is adequately absorbed and distributed, and that the striker's construction is solid. However, this too is a balance because any extra pieces add weight and can reduce the length of draw for the striker, losing range. In general, make the striker as strong as it needs to be for the launcher and its intended use. 
So keep those in mind while building your own launcher. Speaking of which, have you tried designing your own yet? If you have, let me see them in the comments below by linking a URL to your pictures or video. If not, don't worry, we have more to learn and more opportunities for you to customize a launcher of your own. 

Sunday, September 23, 2018

My Beginning

Like many other children, I had a creative side. But while I wasn't as artistic (didn't really enjoy coloring), I did have a fascination for engineering. I recall as a toddler, I would put all of my toys together into complicated "machines" connecting all the electronics and anything that could remotely look like an Input/Output device with strings, tapes, straps, and wires. I also enjoyed building pretend pinball machines with the little knickknacks at my grandma's house. I simply enjoyed knowing how things worked, and I wanted to make things that worked too. That said, I was also a lazy kid, I didn't like working with my hands all that much (wait, I still don't...), I just liked coming up with ideas. Naturally, K'nex made it much easier to build things without all the effort of crafting stuff out of raw materials. I also really enjoyed Lego.

Fast forward to 2007, I had just started my freshman year of high school. A little later on into the year, we had a transfer student who made projectile launchers out of pens and rubber bands. He managed to sell them for a couple bucks a piece, and I wanted in on that sort of money. So I began my search on the internet for office launchers. Eventually it lead me to Lego launchers on YouTube, which I found really interesting but sadly too complex for my skill level. But then I happened upon K'nex launchers on YouTube, and I recalled I had some pieces still. All of my toys from childhood were scattered in large tubs in a closet. I looked through some more videos to find something simple enough and then began searching for pieces in my tubs.

The feeling of building my first launcher isn't something I'll ever forget. The beautiful thing for me was that I quickly learned that I could tweak my builds. I had figured out the basic concepts (that we covered in yesterday's post) and started creating my own variations of simple tube launchers, coming up with more complexities along the way such as a rudimentary bipod and a really basic handle.

The table I sat at for lunch in school was always a little rowdy. To start, they had used plastic utensils, and we discovered that you could bend the prongs on them until they snapped, in which they'd launch off a piece. We'd snap them under the table at each other. Some kids would also use those pen launchers I mentioned earlier. But then they'd often get caught since it was difficult to load, hold, and aim. I was amused that using a K'nex projectile launcher with a trigger, I never got caught because I could easily prime, load, and aim it discretely and fire only when I was sure no one was looking. The other kids complained and I even admitted to having the launcher on my person, but the lunch supervisor proclaimed that if she didn't see it happen, she couldn't get me in trouble.

I happened upon Instructables sometime later that year. I had lurked on it for the most part, but by December I joined and started contributing with very amateur builds and discussion. I was a teenager after all, so most of my comments were probably very cringey. I sought praise and would continue trying to contribute to the budding community.

Here are a few of my early builds:

"Stg-44" I had a lot of interest in real firearms at the time, and had just started learning about WWII firearms. I had just learned how to build a rubber band launcher from someone else's instructions, so I put together their mechanism, a stock from another builder, and then a little of my own improvisation to come up with this crude launcher. For each band you loaded onto the cog wheel and each single-slot connector you loaded in the magazine, you could launch a projectile semi-automatically

"AK-47" I didn't like how unrealistic many other launchers claiming to be AK-47s were. Mine was hardly any better than the ones at the time, but I tried to introduce a removable, curved magazine for something novel

"Mini-Uzi" I apologize for the blurriness, I had yet to acquire a good camera or the skills to use one. As you can tell by now, I had a thing for trying to replicate real firearms. I had just built someone else's Uzi-like launcher with a magazine in the handle and wanted to try out my own.I had designed two other pistols, one being my first YouTube video on a K'nex launcher, the "Mikoflare", and another mini-pistol I called the "Dingo" in a similar style.
I had a few other designs too, but most of them were variations of the above three. I'll get into my better contributions in future posts.

How did you guys get started in building with K'nex? Let me know in the comments.

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.


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 Guide

Sear + trigger


Projectile lock


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


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.


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. 

Thursday, September 20, 2018

Welcome to K'nexpression!

Hey, all. First off, if you're reading this, I appreciate that you took the time to come here. While we all have varying levels of passion for building with K'nex, I hope either yours is already strong or that I might help you find more, and that you can contribute to our community in time.

So what is K'nexpression? Long story short, it's a place where, as a builder, I want to engage with and help establish more of the K'nex community, specifically the projectile launcher community. While there exist smaller communities on other sites such as YouTube, Reddit, and independent fan sites, they tend to be inactive or perhaps more focused on other areas of building. Sadly, the community for K'nex projectile launchers has been dwindling and scattered about. I'd like to drive interest into the hobby again by providing a place to discuss the hobby and provide guides and instructions to help new builders jump in. Eventually, I hope to develop this site into something more than just a blog.

And who am I anyway? While I don't mean to act like any big hotshot worth noting, the one thing I can brag about is having been a part of the community for a while. I started on Instructables back in late 2007 under the user "TheDunkis". For those unfamiliar, Instructables is a website for posting instructions on DIY projects, which naturally attracted some K'nex builders to utilize it, creating a fairly strong community for several years before it started dying off. The first projectile launcher posted there was on June 7th, 2006 by user "(your name here)", so while I was a year and a half late to the party, I wasn't too far behind and would stick around until this very day, not giving up the hobby. I've created my fair share of builds that we'll discuss in future posts. I'd also like to go over the history of important developments in K'nex projectile launcher building.

That's all for today. Thanks again for stopping by. I hope you'll stick around. In my next post, I want to show anyone new to building projectile launchers just how easy it is to get started with a simple build that'll take only 13 pieces and a rubber band.