Zip3 Final Prototype

About: Hello. I'm JonnyBGood! I'm a college student who now has a degree in Mechanical Engineer Technology. (MET) (excessively worded to mean a person who builds stuff).I enjoy building K'nex guns and many other th...

Zip3, the best k'nex gun in my arsenal. Its a pump-bolt action knex gun that's contained within five layers of K'nex. I've been working on this gun since its initial post about a year ago. As all my knex guns go when I post a preview, usually I have a rough working gun that looks decent. Zip3 was the same way, that's why I've spent the time to build my ninth version of Zip3 which is the best version so far.
As far as internals go, it a hasn't changed much from the preview: now it can be dry fired, slightly better trigger, uses one broken piece on the gun and three per magazine. It also has however gotten longer, a larger cleaner pump, more pump rod support, and larger magazine capacity. The trigger is still the weakest part of this concept due to very tight space constraints, but its capable of holding back 3 rubber bands (2 #64's and slightly smaller one).
Overall this gun is my piece de resistence, the best I have and I apologize for missing my deadlines for those looking forward to a post, I procrastinate far too frequently. I also apologize for the quality of some of the pictures, I thought it was just a camera issue and really it was just dirt on my camera lens! Anyway I'm back and ready to answer questions if you have them, just leave me a comment.

Alright let's get building this beauty!

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Step 1: The First Layer

Well all K'nex guns start the same way, lets start by buiding this massive first layer. I also show a detail piece I use as support. Note that this piece is purely for support and doesn't make the gun 7 layers, the gun is fully functional without it. For those who are building another layer for the final step, you don not have to include the blue spacers on the black rod.

Step 2: Little Pieces

Well as the name suggests, this step is to put all those annoying little pieces on the gun. If there is any questions feel free to ask in the comment bar.

Step 3: Trigger, Chambering Mechanism, and Barrel

Alright we are done with those annoying little bits of gun parts, we move to the larger sub-assemblies. Starting with the dreaded and heavily revised trigger mechanism. The hinge is attached to the yellow connector and then taped tightly with electrical or any other tape. Make sure the tape does not interfere with the joint. After that you get to see how I build bolt action mechanisms. It relies on two elastic powered arms, the lower pushes the ammo up and the top levels the ammo as it is chambered. This allows you to unjam the gun easily by lifting the top chambering arm, which will allow the rod to slide down the barrel. Finish this step by building the top of the barrel.

Step 4: Grip and Trigger Guard Assembly

Now for the grip and trigger guard, which I believe ties this entire gun together. The entire step is pretty straight forward, however as you can see I use a little cut piece in the trigger. This piece is optional! I would highly recommend this piece for people who intend on using this gun a lot, because this will allow a more responsive trigger.

So, if you plan to have this gun assembled for about a week, I'd skip it. If you plan to have your gun together for longer than that, please use that piece.

Step 5: Pump and Final Assembly

Alright now it's time to build the pump! I revised this part over fall break, producing a larger and more comfortable forward pump. Notice the step order; build the pump rods, the pump, add the top layer, then the last pieces of the pump.

Step 6: Rubberband Placement

If you made it this far Congradulations! You have finished all the K'nex parts of the gun and now it's time to add the rubberbands. This gun is a bit finicky on band placement on the chambering arms. Make sure that the bottom chambering arm is tighter than the top chambering arm. This doesn't mean that the top chambering arm should be loose either. Regardless tighten a loosen the arms to ensure the yellow rod is chambered straight in the gun.

Step 7: Magazine

Well, you have the gun now for the magazines! Make sure to make two of these if you can to enjoy the full potential of you gun. Also if you have any previously broken y-clips, I'd highly recommend placing them on the tabbed side of the magazine, and the taping them to the orange connector.

Step 8: Finished!

Good Job completing your very own Zip3! I'm glad that you took the time to build or look through the ible of this gun. I must say that I personally love the Zip3 system and I plan on applying it to several new guns in the future. If you've built Zip3, I'd love to hear what you think about it and see pictures if you have any. Anyway it's been a pleasure as always, thanks for building!


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56 Discussions


Reply 3 years ago

No unfortunately, I've had a bit of a change in interest lately however I'll probably get some concept sketches up in a forum when I find time to do it.


4 years ago

OK... ive built the entire thing except for the msg. this is an awesome design and looks uber functional, but for the trigger the block trigger is kind of at it's limit here... I'm going to try building a rear catch setup that locks onto the two grey pieces on the ram at the back.

1 reply

Reply 4 years ago on Introduction

Sorry for the late responce but tell me what you come up with! I'm always trying to improve my Zip design for the next model so I'd be glad to try your mech. Also look up KILLERK's videos about Zip3 because his trigger is the best I've tried so far!


Reply 4 years ago

I would say so! It's been about of year of little tweaks and upgrades that's made this gun the deffinition of my original ideas and mechanisms. I'm glad you like it as well.

sonic broom

4 years ago on Introduction

I built this and it is not working I changed my mag to be like killerk's but it still is not working. the ram does not hit the ammo also the trigger does not feel that good and the handle is kind of awkward to hold. But anyway it is a very neat mech.

i will take this apart soon i need the parts for a different gun. i built it more to learn about pump action then to do a lot of shooting so i did learn a lot! and it was a good experience to make it.

Hope you don't take this as a negative feedback it just failed to live up to my expectations.

1 reply
JonnyBGoodsonic broom

Reply 4 years ago

Well, I guess I'm sorry it didn't meet your expectations....
As you can tell by the plethora of problem concerned comments I've gotten, Zip3 is a "tuned" gun. It requires some specific band placement and other quirks to make it work properly.
Overall I may have been able to make this easier to use if I just used a generic ZKar mechanism but I wanted this design to be my own vision, inside and out.
I am working to create a more "user friendly" version of this mechanism that requires no tuning and I'm planning to apply it to Zip4. Maybe try building a different pump action to try because Zip3 is a lot different internally than all of the pump actions on this site.


Reply 4 years ago

Well while I am Very happy with how this out, there are many more pump-action concepts that have even more range potential. I aim at making the Zip line of guns a concept filled series that finds and extracts the most potential from the pump-action layout.
In a more summarized sense Zip3 is good, but it can be better. Zip4 is planned to be a magazine fed, chambering, pump-action slingshot. However I have not planned how to actually make this yet, so it'll be awhile until the preview will surface.
Thanks for building and enjoying my Zip series!


Reply 4 years ago

yep also Kinetic made a pump action slingshot shotgun. I'm hoping to get something better than Zip3 range wise anyway...

Lucas The Boss

4 years ago

Came so close, all I need is pieces for the mag. Waiting for my order. The mech works fantastically though

15, 5:18 PM.jpg
4 replies

Just out of curiosity, how yellow connector did you have before buying more? If you don't know that's fine. I was just curious if you know that and green rods you used to build it because I don't really feel like counting them for sonic broom.

Well I only needed like 10 more yellow but I'm planning much bigger projects so I ordered 300. If you want I'm fixing to take it apart and build my own bolt action, so I can give you a green rod/yellow connector peice count.

JonnyBGoodLucas The Boss

Reply 4 years ago

I hope I'm not to late, but please if you could give me the piece count that would be awesome.