Introduction: "Gunzo the Great" Knex Semi-Automatic Rubber Band Gun

Picture of "Gunzo the Great" Knex Semi-Automatic Rubber Band Gun

This is a Semi-Automatic Rubber Band Gun (by which I mean it SHOOTS rubber bands, since I think the ones that shoot rods hurt too much). It's designed to be as RUGGED as possible, because I was tired of stopping our RBG wars every 2 minutes because somebody's gun broke.

The spacing of the 2 gears that make up the repeater mechanism at the heart of this gun was adapted from MrRadicalEd's RBG Repeater, because it's so simple and works better than all the more complicated ones I've made or tried.

Picture 1: Complete "Gunzo The Great"
Pictures 2&3: Shows my adaptation of MrRadicalEd's 2 gears. (just a model demonstrating the size and relative positioning of the gears)

Thanks to MASTERMIND for the piece count:
6 white connectors (8-way)
38 yellow connectors (5-way)
6 green connectors (4-way)
20 red connectors (3-way)
4 light gray connectors (2-way)
2 dark gray connectors (1-way)
2 blue tabless (or tan tabbed) clip connectors

97 green rods
34 white rods
9 blue rods

7 blue spacers

Step 1: The Gun Sides

Picture of The Gun Sides

Build 2 of these. These are the Gun Sides.
Note, the Red Connector in the middle is missing in a few of the later pictures. That was a mistake. It is always supposed to be there.

Step 2: Trigger and Spinner Wheel

Picture of Trigger and Spinner Wheel

Picture 1: trigger pieces. Note the blue spacer, and the dark green rubber band.
Picture 2: spinner wheel

Step 3: Barrel Pieces

Picture of Barrel Pieces

Make these Barrel Pieces and set them aside

Step 4: Handle Pieces & Odd Parts

Picture of Handle Pieces & Odd Parts

Pic 1: Make 4 of these. We'll call these "Handle tips"
Pic 2: Make 2 of these. We'll call these "Handle Spacers"
Pic 3: Make 1 of each of these. They are the "Red Handle Base" and the "Yellow Handle Base"
Pic 4: These are called "Through Rods" or Thru-rods. (All Orange connectors are temporary)
Pic 5: These are Side Clips. You'll actually need to take the grey connector off of the white Snowflake connectors, and replace them at the end of step 9.

Step 5: Assembly: Trigger Area

Picture of Assembly: Trigger Area

Pic 1: Slide Thru-Rods through the back side of one of the Gun Sides
Pic 2: Turn it back over
Pic 3: Hold Trigger pieces as shown
Pic 4: Place Trigger on Front Thru-Rod, and a blue spacer on Rear Thru-Rod
Pic 5: Add Spinner Wheel. then another Blue Spacer to rear Thru-Rod
Pic 6: Add Orange connectors to both Thru-Rods. These are just temporary.

Step 6: Assembly: Handle

Picture of Assembly: Handle

Pic 1: Add Yellow Handle Base
Pic 2: Add Red Handle Base
Pic 3: Add a handle tip as shown
Pic 4: Add all handle tips
Pic 5: Add handle spacers (gun has been rotated, but not flipped)
Pic 6: Add second handle spacer (the gaps are not necessary)

Step 7: Assembly: Barrel Top

Picture of Assembly: Barrel Top

Pic 1: Attach these barrel pieces
Pic 2: Attach yellow connectors as shown (I used grey ones so you could see the layers better)
Pic 3: Attach 2nd yellow/grey
Pic 4: After attaching 3rd one, you can add the green rods
Pic 5: Repeat steps from Pics 2-4, to create the second internal layer

Step 8: Assembly: Barrel Bottom

Picture of Assembly: Barrel Bottom

Pic 1: Add one of the remaining Barrel pieces as shown, adding one more green rod .
Pic 2: Add 1 green rod to the bottom of each of the 6 center yellow/grey connectors)
Pic 3: Attach a yellow connector to the blue rod. See pic note.
Pic 4: Then slide the yellow down to snap into layer 2. Add the green rod.
Pic 5: Make 2 pieces like the one shown here. The other is shown already attached. Do it now.
Pic 6: Repeat steps from Pic 4-5 to finish layer 3
Pic 7: Add final barrel piece, then insert green rod where pointer is pointing

Step 9: Assembly: Finishing Up

Picture of Assembly: Finishing Up

Pic 1: Compress all pieces on blue rods. remove orange connectors from thru-rods
Pic 2: Add second gun side, sliding over thru-rods, snap into place.
Pic 3: Add blue connector to rear thru-rod. Add orange connector to front thru-rod
Pic 4: Snap in blue rod, with 4 blue spacers
Pic 5: Remove orange connector from front Thru-Rod, replace with white "snowflake" connector. repeat on both sides, making sure they're oriented the same way.
Pic 6: Rotate the snowflake clockwise until the blue rod is in the SouthWest corner, and the other blue rod is straight below the center. It will be tricky to work it past the other blue without disconecting either. Attach green rod and grey connector as shown. Repeat on both sides.
Pic 7: Attach Side Clips as shown, on both sides.
Pic 8: Arrange trigger spacer and rubber band as shown, the spacer will keep the RB from getting chewed up as you fire the gun.
Pic 9: stretch rubber band over tip of gun and seat as shown
Pic 10: Insert white rod through base of trigger.
Pic 11-12: Use a rubber band to secure the white rod in place. Pattern doesn't matter, it just needs enough tension to not slide out.

Step 10: Loading Rubber Bands & Trouble-shooting

Picture of Loading Rubber Bands & Trouble-shooting

Sorry these pictures are so dark. I'll try to take new ones in daylight.

Pic 1: clip Rubber band in gun tip. Stretch to the spinner wheel.
Pic 2: Insert the rubber band behind the first white rod that is pointing backward.
Pic 3: NOTE: make sure you get the RB in the V of the connector,
Pic 4: WRONG WAY: If you do it like this, the rubber band may get stuck, and misfire.
Cock the gun by pulling the wheel backward until it clicks once.
Start again at step 1. Always put the RB on the rod in the position shown in Pic 2.
When you go to fire the gun, the first time you pull the trigger, it won't shoot. Rubber bands begin to release on the second pull.

PROBLEMS: If you pull the trigger once, and all rubber bands fly off, you may have put on too many Rubber bands. It all depends on the type of RBs you're using, and the stiffness of your Knex pieces. Try this. Load only 2 RBs. Fire the gun. If the rubber bands shoot individually, as intended, reload the gun with 3 RBs and see if that works. Keep working up until you know the limit of your gun. If the gun still misfires with only 2 Rubber Bands, make sure all the connectors are snapped, especially inside the trigger chamber. If that still doesn't help, try bigger RBs or shorten the barrel of the gun.

Step 11: Variations

Picture of Variations

Here are some pictures of a wider variation of the semi-auto assembly. Note, the major difference is 2 blue spacers on either side of the revolver spool, instead of 1. The down side is, it requires Yellow Through rods, which is a little annoying on a pistol, but is no problem in a Rifle.

Pic 1 - Overview of the Original Build of the Semi-Auto Assembly on the pistol. Here you REALLY see the similarities to Mr Radical Ed's.

Pic 2 - Overhead view of pic 1

Pic 3 - My sniper variant - Shoots 12" bands I got at Staples / Office Depot

Pic 4 - Sniper Semi-Auto Assembly

Pic 5 - Barrel Detail for the Sniper Rifle


siamesederp made it! (author)2017-04-17

This is amazing! Very fun and strong, I guess you could sell one of these for $10-$20 based on price of parts and shipping and the grip feels amazing.

randoman221 (author)2014-04-10

cool this is amazing!

shoots 100 ft.

wiishadow4 (author)2010-05-03

 best knex gun ever.

megustatrains (author)wiishadow42013-07-16

there is better (not that this isn't good) likes the s3. its is semi auto and shoots pieces.

Inventor X (author)2011-06-28

This is totally my choice of weaponry in a RB war. Compact, sleek, and has a ncie look. The trigger is a light pull, and has modding capabilities. Thanks for building such a great gun! (No wonder it's called "Gunzo the Great" !) :)

Spycrab (author)2010-06-18

I LOVE this gun. It's a big gun, which is sweet and all, but for people with only a few pieces, (like me),well, it uses a lot of pieces. It is WELL worth it, though. =D 5*, you deserve it.

123bob321 (author)2009-11-11

danroy, its clear enough to "see" and make
so why complain?

123bob321 (author)2009-11-10

This is my favorite RBG. =D

brammeke11 (author)2009-02-05

This is the first Repeating rubberbandgun

revtiedye (author)brammeke112009-09-02

Yep, that's the same one I mentioned in the description. Thanks to Mr. Radical Ed's design. I think I'm going to send him another thank you note.

brammeke11 (author)revtiedye2009-09-03

Ow, sorry. didn't read that the first time

eskimoboy (author)2009-08-29

Hey, this is really great design. You managed to make the gun strong without requiring us to clip 7 connectors onto a rod all at the same time in an internal space while doing a dance and baking a pie.

revtiedye (author)eskimoboy2009-09-02

Yeah, thanks. I'm not a big pie fan, and I'm a terrible dancer, so I never got into that style of Knex Design.

ponddust1 (author)2009-07-27

you can still see what your doing

danroy99 (author)2009-07-13

blurry picture

randomocity (author)danroy992009-07-15

it's not that bad

101man (author)2009-07-15

best knex rbg EVER!!!!!!!!!!!!!!!!!

stopanator (author)2009-07-07

rev nice gun but i need a bit clearer instructions sorry but adleast this gun is still the best rbg pistol

deaniscoolproductions (author)2009-06-06

best rbg gun ever total 5 star :D

Thanks for that encouragement! I know the gun can work well, although it apparently doesn't work for everybody. I thought maybe my instructions weren't clear enough. I'm glad you were able to use them for a successful build.

Miles Tails Prower (author)2009-02-16

I combined this gun with knexguntutorials's shotgun. The result? Good.+

Nice Miles! Thanks for uploading the pic!

Oompa-Loompa (author)2008-07-21

Why do all knex rbg's jam a considerable amount?

Not all, just semi-auto ones anyway...

osi (author)Oompa-Loompa2008-07-24

not all do they work quite well actually it just may be that if you make it and forget a single spacer or something like that it jams

Oompa-Loompa (author)osi2008-07-24

I build some of em with large spokes on the wheel like this one, and the band doesn't even pull off of the wheel sometimes.

osi (author)Oompa-Loompa2008-07-24

are you holding down the triger? sometimes that causes it to do that, also you could try lengthening the barrel to create more pull on the gear

The Creatornator (author)osi2009-03-23

Is your avatar like a russian MiG or something (and yes, I do know what a MiG is)?

osi (author)The Creatornator2009-05-27

my avatar is the Russian su-37. the f-22 raptor was designed to combat this aircraft. however, Russia came up with the su-47, which is faster and can carry more ordinance than the f-22. to answer your question, the mig-31, was the original frame for the su-27. this evolved into the su-35. that was redesigned to the su-37, my avatar.

Oompa-Loompa (author)osi2008-07-25

I don't hold the trigger, and the shot flies off with the next one, but I don't have the knex to mod every gun I build. thanx anyway.

osi (author)Oompa-Loompa2008-07-25

how many ruber bands do you use and how thick are they, if you try lowering the thickness or lowering the number then your last effort would be to use stronger knex pieces at the triger and spoke areas

Oompa-Loompa (author)osi2008-07-25

The bands aren't too thick, but not quite thin. However, they are sort of weak. And it's not that the knex pieces are messed up, the spokes are just too long.

osi (author)Oompa-Loompa2008-07-26

well the only thing you could do is lengthen the barrel, I lengthened my barrel on the top by 2 yellow half circles which ended up giving me 20 extra parts, which i think is resonable

Oompa-Loompa (author)osi2008-07-26

i'm more interested in knex guns that shoot rods anyway. So I'll just forget about knex rbgs for now

revtiedye (author)Oompa-Loompa2008-07-29

When you load the rubber bands, loop it over the first rod that is leaning backwards. On this gun, it's about One O'clock. And make sure the rubber band rests on the wheel connector NOT on the rod. If you just place it on the rod, after you load more rubber bands, the tension will pull the RB down and get pinched between the rod and the connector, and jam. I've been doing it this way so long, I forgot there was any other way, and was amazed at your original comment. My guns never jam.

Oompa-Loompa (author)revtiedye2008-07-29

I know that is how you load the gun, but when the spoke leans forward, as to release the band, the band just slides like halfway up the spoke instead of coming off.

revtiedye (author)Oompa-Loompa2008-08-10

After you load the gun this way, the first time you pull the trigger it won't fire, but from then on, it works great. Alternately, you can load the last rubber band without cocking it, and you're set to go. Again, I've been doing it this way so long, I forget to state what seems obvious to me. But I've got several of these around the house, and we have wars all the time. And they never, ever jam. Once you learn how, it's easy. Sorry it's so hard to learn.

Oompa-Loompa (author)revtiedye2008-08-11

Forget it you have no clue what I'm talking about... So stop acting like I'm the clueless one here, k?

revtiedye (author)Oompa-Loompa2008-08-21

Oompa Loompa,

I'm really sorry you took offense at my answer. I absolutely don't think you're clueless. I know for certain I'm a terrible communicator, because I always use too many words, and say the same thing over and over again. I forgot I had added an entire step in the instructible on "how to load the gun." I didn't realize I was just repeating myself.

It's just what you said:

but when the spoke leans forward, as to release the band, the band just slides like halfway up the spoke instead of coming off."

...that's a perfect description of how the gun works, except that's not when it's supposed to "release the band." It's not supposed to release until you pull the trigger again.

Thanks for letting me know I ruffled your feathers. Otherwise I never could have apologized.

Oompa-Loompa (author)revtiedye2008-09-13

Maybe my bands were too small, because sometimes when it's apparently "not" supposed to come off when the spoke leans forward, it will every once in a while, either jamming the gun or shooting two shots at once. But I wasn't trying to start an argument, sorry bout that.

DrWeird117 (author)Oompa-Loompa2008-08-29

i builted a semi auto ketchup gun!!!!!!!! load 9 ketchup packets into the handle, cock the slide, and as you pull the trigger, it squeezes the pack w/ hella force! a spray of catsup comes out the front and the slide is automatically pulled back and releases the empty pack!!!!!! it is semi auto. pull trig. splat. repeat.

DrWeird117 (author)DrWeird1172009-03-18

Notice the intentional "builted".

Oompa-Loompa (author)DrWeird1172008-09-13


DrWeird117 (author)Oompa-Loompa2008-09-13

I'll try and perfect it and post. It isn't K'nex.

Oompa-Loompa (author)DrWeird1172008-09-13

I don't have any spare ketchup packets...

DrWeird117 (author)Oompa-Loompa2008-09-13


Oompa-Loompa (author)DrWeird1172008-09-13

LOL I hate McDonald's

DrWeird117 (author)Oompa-Loompa2008-09-13


Oompa-Loompa (author)DrWeird1172008-09-13

LoL, what do you need to make the gun?

DrWeird117 (author)Oompa-Loompa2008-09-13

wood. and some PVC.

About This Instructable




More by revtiedye:Using Adhesive-Backed Floor tiles to make Print & Play BoardGames"Gunzo the Great" Knex Semi-Automatic Rubber Band Gun"The Teazer" Knex Semi-Automatic Rubber Band Gun (RBG)
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