The First Fully Automatic, Clip Fead, LEGO Nerf Gun: Raptor CS-35




Introduction: The First Fully Automatic, Clip Fead, LEGO Nerf Gun: Raptor CS-35

About: Technologically mad, environmental scientist.
This is my first Instructable, So hello.

Have you ever thought what would happen if you combine LEGO with Nerf? Well it turns out you get this....
I have had two of these guns for about a year now, and want to share it with the world now that I have finished university.
The concept came from the barricade, and wanted to modify but I didn't want to damage it (as it was a present from a friend).

-Range: over 15 meters /50 feet
-Rate Of Fire: 35 darts in under 17 seconds
-Lithium Ion powered (14.8v 900 MAh) lasts up to 8 Hours of use
-Sturdy in battle, no bits drop off when being handled roughly, yet the parts are not glued together in any way, only 3 switches are glued onto the sides of a few bricks.
-Firing push rod always resets itself to quickly fire the next shot, with a smart circuit to eliminating misfiring.
-Light enough to duel wield. (The club I was in stopped me doing so, as I consistently owned them with it) ^_^
-Volume is less than the Nerf Barricade
-Customizable color (red, blue, yellow, white, black or a combination of them)

Well...... see what you think (And if you like it Please Comment, Rate and Vote for it)
And if you are building it, please let me know how it is going/went.

Firing demo:

A 3D look at the gun.

A close up look of the internal mechanism:

As you can see from the video, there is a easily accessible safety switch which turns the gun on and off, and a Voltage indicator that shows my gun is 90% charged.

The video shows how the push rod always resets itself back into the same position every time a shot is fired, without this circuit there was a potential lag between pressing the trigger and firing a shot, the circuit also eliminates the gun miss-firing a second shot.

The cogs are used to slow the motor down 5:1, there is potentially a way to change the gearing to increase the rate of fire, I like the speed that it is now, but feel free to experiment.

Step 1:

Caution, this project uses Lithium Ion Cells.

I recommend you buy "protected" cells, however IF using unprotected cells you should defiantly use a voltage indicator.

0)Never put 14500 cells directly into a device that uses AA batteries.

1)Use specific Lithium Polymer/Li-ion charger only. Do not use a NiMH or NiCd charger- Failure to do so may a cause fire, which may result in personal injury and property damage.

2)Never charge batteries unattended.When charging LiPo/Li-ion batteries you should always remain in constant observation to monitor the charging process and react to potential problems that may occur.

3) Some LiPo/Li-ion chargers on the market may have technical deficiencies that may cause it to charge the LiPo/Li-ion batteries incorrectly or at an improper rate. It is your responsibility solely to assure the charger you purchased works properly. Always monitor charging process to assure batteries are being charged properly. Failure to do so may result in fire.

4)If at any time you witness a battery starting to balloon, swell up, smoke or hot, discontinue charging process immediately, disconnect the battery and observe it in a safe place for approximately 15 minutes.This may cause the battery to leak, and the reaction with air may cause the chemicals to ignite, resulting in fire.

5) Since delayed chemical reaction can occur, it is best to observe the battery as a safety precaution.observation should occur in a safe area outside of any building or vehicle and away from any combustible material.

6)Wire lead shorts can cause fire!If you accidentally short the wires, the battery must be placed in a safe area for observation for approximately 15 minutes. Additionally, if a short occurs and contact is made with metal (such as rings on your hand), severe injuries may occur due to the conductibility of electric current.

7) A battery can still ignite even after 10 minutes.

8) In the event of a crash due to bad shipment or other reason, you must remove battery for observation and place in a safe open area away from any combustible material for approximately 15 minutes.

9) If for any reason you need to cut the terminal wires, it will be necessary to cut each wire separately, ensuring the wires to not touch each other or a short may occur, potentially causing a fire.

10)To solder a connector: Remove insulating tape of Red wire and solder to positive terminal of a connector, then remove insulating tape of Black wire and solder to the negative terminal of connector. Be careful not to short the wire lead. If you accidentally cause the battery to short, place it in a safe open space and observe the battery for approximately 15 minutes.A battery may swell or even possibly catch fire after a short time.

11) Never store or charge battery pack inside your car in extreme temperatures, since extreme temperature could ignite fire.

12) Never drop the batteries.

13) I suggest you put the battery in an enclosure to protect it from damages by liquid or dropping from height accidentally.

Step 2: Parts List and Tools.

All required LEGO pieces can be obtained from
Electrical parts were obtained from but I highly recommend
Lithium Ion 14500 (AA size) batteries and charger from Ebay
(I recommend protected cells, however they may not fit in the battery enclosure, if you decide on unprotected cells use the voltage indicator)

Heat gun or lighter
A small clamp
Some Strong Glue/Epoxy (not Super glue)
Fine file
A Multi-meter with resistance test.
Wire cutters
Wire strippers
Soldering Iron
Solder and Flux
Electric Drill
2mm and 4mm drill bits
Metric ruler.

Electronic parts:
2X micro switches-(maplin: GW67X) (Specifications: Body size-12.8 x 6.5 x 5.8mm, Contact rating-3A 125Vac)
1X on/off switch----(maplin: FF77J) (Specifications: Body size-11 x 5 x 6mm, Front plate-19 x 5mm, Tang-3.8mm long (throw 3mm))
1X micro DPDT 12V relay--(maplin: N17AW) (Specifications: Dimensions-20 x 10 x 9.9mm, Nominal Voltage-12VDC, Switching capacity-1A @ 125VAC)
Quad AA Battery box (flat and with leads)
4x Lithium Polymer 14500 batteries 3.7v 900mah
Charger for 14500 batteries

This allows you to view the current charge within the batteries, I would advise fitting it, so you can go into battle knowing your batteries are full, or need to be replaced/recharged. Also reduces the chances of over discharging unprotected Li-Po cells.

Lego parts: (sorry this site removes multiple spaces)
No.--Color--------Part no.------Part name
1----Yellow-------2436----------Bracket1 x2 -1 x4
6----Black--------6111----------Brick1 x 10
2----Yellow-------3005---------Brick1 x1
1----Black--------3005----------Brick1 x1
1----Yellow-------3004----------Brick1 x2
10---Yellow------3622----------Brick1 x3
7----Black--------3622----------Brick1 x3
6----Yellow-------3010----------Brick1 x4
1----Yellow-------3009----------Brick1 x6
3----Yellow-------3002----------Brick2 x3
2----Black---------3002----------Brick2 x3
4----Yellow-------3001----------Brick2 x4
1----Light Gray---71427c01---Electric Technic Motor9v
2----Light Gray---2838c01----Electric Technic Motor9V
1----Black--------5306bc020--Electric Wire 20 stud (16 Cm)
1----Black--------5306bc069--Electric Wire 69 stud (55 Cm)
4----Black---------4477---------Plate1 x 10
7----Yellow--------3024---------Plate1 x1
12---Yellow-------3023---------Plate1 x2
4----Black---------3023---------Plate1 x2
4----Yellow--------3794---------Plate1 x2 with 1 Stud
5----Yellow--------3623---------Plate1 x3
4----Black---------3623---------Plate1 x3
17---Yellow-------3710---------Plate1 x4
4----Black----------3710--------Plate1 x4
8----Yellow--------3666---------Plate1 x6
4----Black----------3460--------Plate1 x8
6----Yellow--------3460---------Plate1 x8
3----Yellow--------3021---------Plate2 x3
6----Yellow--------3020---------Plate2 x4
2----Black---------3029----------Plate4 x 12
1----Yellow--------3031----------Plate4 x4
5----Yellow--------3032----------Plate4 x6
4----Black---------3032----------Plate4 x6
2----Yellow--------4286----------Slope Brick 333 x1
1----Black---------4286----------Slope Brick 333 x1
2----Yellow-------3040b-------- Slope Brick 452 x1
4----Black---------3665----------Slope Brick 452 x1 Inverted
4----Black---------3039----------Slope Brick 452 x2
24---Black--------3660----------Slope Brick 452 x2 Inverted
4----Black---------3038----------Slope Brick 452 x3
8----Black---------3037----------Slope Brick 452 x4
19---Light Gray--3749----------Technic Axle Pin
1----Black---------32062--------Technic Axle2 Notched
4----Black---------4519----------Technic Axle3
8----Black---------32073--------Technic Axle5
1----Black---------32278--------Technic Beam 15
11---Black---------6632---------Technic Beam3 x0.5 Liftarm
2----Black----------32009-------Technic Beam3 x3.8 x7 Liftarm Bent 45 Double
4----Yellow--------32009-------Technic Beam3 x3.8 x7 Liftarm Bent 45 Double
1----Black----------2825---------Technic Beam4 x0.5 Liftarm with Boss
1----Yellow--------32316-------Technic Beam5
14---Black---------32017-------Technic Beam5 x0.5
2----Black----------32063-------Technic Beam6 x0.5
14---Black---------32065-------Technic Beam7 x0.5
1----Black----------32177-------Technic Beam7 x1 Liftarm with Ribs and Fan
4----Yellow---------2730--------Technic Brick1 x 10 with Holes
8----Yellow---------3895--------Technic Brick1 x 12 with Holes
5----Black----------3895--------Technic Brick1 x 12 with Holes
5----Yellow---------32018------ Technic Brick1 x 14 with Holes
7----Yellow---------3703--------Technic Brick1 x 16 with Holes
6----Black----------3703--------Technic Brick1 x 16 with Holes
2----Yellow---------3700--------Technic Brick1 x2 with Hole
13---Yellow--------3701--------Technic Brick1 x4 with Holes
1----Black----------3701--------Technic Brick1 x4 with Holes
13---Black---------3894--------Technic Brick1 x6 with Holes
14---Yellow--------3702--------Technic Brick1 x8 with Holes
5----Light Gray----3713--------Technic Bush
3----Light Gray----32123a-----Technic Bush 1/2 Smooth with Axle Hole Reduced
1----Light Gray----6536--------Technic Cross Block 1 x 2 (Axle/Pin)
6----Black----------6536--------Technic Cross Block 1 x 2 (Axle/Pin)
2----Light Gray----3649--------Technic Gear 40 Tooth
1----Light Gray----3647--------Technic Gear8 Tooth
1----Black----------44350-------Technic Panel Fairing #20
1----Black----------44351-------Technic Panel Fairing #21
1----Light Gray----4274--------Technic Pin 1/2
13---Black---------6558--------Technic Pin Long with Friction and Slot
7----Black----------4459--------Technic Pin with Friction
29---Dark Gray---32002-------Technic Pin3/4
2----Black----------4442--------Technic Plate1 x8 with Holes
3----Yellow--------3709b-------Technic Plate2 x4 with Holes
5----Light Gray----731----------Technic Shock Absorber6.5L
1----Yellow---------3069b------Tile1 x2 with Groove
1----Yellow---------3068b------Tile2 x2 with Groove
2----White----------2903--------Wheel 81.6 x 15 Motorcycle

Step 3: Wiring the Internals

Follow the steps to make the internal electronics.

The voltage indicator allows you to see the remaining charge contained within the battery, this is extremely useful when using unprotected batteries, and for determining if there is adequate charge for use in battle.

If you want to use the voltage indicator, have a look at the user manual, and set both dip switches in the off position.
Remove the clear layer of protective plastic, so it will fit in the hole in the LEGO.
Cut the socket off as close to the connector as you can, so you have the maximum length of cable left attached to the circuit.
Connect the wires to the indicated points in the instructions.

Step 4: Building the Body

Step 5: Building the Body

Step 6: Building the Body

Step 7: Building the Body

Step 8: Building the Body

Step 9: Building the Body

Step 10: Building the Body

Step 11: Building the Flywheel

Step 12: Finishing Touches

And there you go, you should now have your own Raptor CS-35.
Have fun and play nice :)

Step 13: Range/Power Improvement

Here are a few, more advanced modifications I have done to improve the performance of the gun.
Replacing the accelerator motors if the most noticeable modification that I did, as it doubled my range to about 30m/100ft
I replaced the original Lego motors with two "Nichibo PC-280" motors that I found on ebay.

Remove the motor case by following the images, whilst trying to do minimal damage to the plastic.
-Force a guitar pick under one corner of the case
-Using a small screwdriver, gently release the closest clip.
-Move the guitar pick along, and release the next clip.
-Do this until all of the clips are released.
-Remove the top.
-Take the motor off the base.
-Remove the Lego shaft connector, by gently levering it with a screwdriver.
-Remove the power connector,by gently levering it with a Guitar pick
-Now get the new motor, with the text facing up, re connect the power connector.
-Push the lego shaft connector on, and see if it fits tightly. if it doesn't, put a very small drop of glue on the inside of the Lego shaft connector, and the push it onto the motor.
-Re-fit the case (follow to images in reverse order, if unsure)

In case the motors are no longer listed, here is the specifications of the motors.
  • Motor manufactured by Nichibo
    Model: PC-280-16210
  • Operates on 6 VDC nominal
  • Operating voltage range: 3 VDC to 12 VDC
  • No load speed at 6 VDC: 6,000 RPM
  • No load current: 70 mA
  • Full load (maximum efficiency @ 6 VDC) performance characteristics:
    • Speed: 4,260 RPM
    • Current: 280 mA
    • Torque: 18.03 g-cm (1.77 mN-m)
    • Power output: .8 Watts
  • Stall torque: 81.9 g-cm (8.04 mN-m)
  • Stall current: 980 mA
  • Dimensions (not including shaft): 30.5 mm long x 18.3 mm thickness x 24 mm diameter
  • Shaft dimensions: 9 mm long x 2 mm diameter
  • For more information, please click this LINK to see the data sheet (PDF - 212 kB)

Step 14: Other Modifications

Coming sometime soon:
Making the gun able to be dual-wielded.
Increasing firing speed.
Variable speed firing rate, using a cheap and easy 555 PWM speed controller.(showing placement of components on perf-board)

4th Epilog Challenge

Participated in the
4th Epilog Challenge

Hack It! Challenge

Participated in the
Hack It! Challenge

2 People Made This Project!


  • Electronics Contest

    Electronics Contest
  • Tinkercad to Fusion 360 Challenge

    Tinkercad to Fusion 360 Challenge
  • Science Fair Challenge

    Science Fair Challenge



5 years ago

By chance do you have an LDraw or LDD file available to download, and a bill of materials?


6 years ago

I'm only 12 and I used you GREAT idea to great something hing very similar, I made the weels virtical instead of horizontal and managed to get about 75+ feet. And I redid the shell to make it more streamlined and ordered a stronger motor. And I have my machine shooting boomco darts which seem to go further.


7 years ago on Introduction

I don't know if this will be answered, but how do you keep the clip from falling out? I am trying to build a lego Mindstorms version, inspired by this one. Also, approximately how fast are the flywheels spinning? Do you think I could build it with smaller flywheels, or should I buy that part 2903?


10 years ago on Introduction

OMG that's epic!!!!!!!! man that must have taken SO long to build!! Nice!

Raptor Z
Raptor Z

Reply 10 years ago on Introduction

Thanks, I designed it with practicality, and reliability in mind.

It was strangely easier to make it fully auto than semi auto.
I have also managed to upgrade it to get 80 feet (level)

Raptor Z
Raptor Z

10 years ago on Introduction

Woo, I just got some replacement motors from Lego ^_^

I will also be posting a tutorial on how to repair a few causes of the seizing problems with the 71427 Lego motors, and how to repair/upgrade the speed of the 2838 motor.

Raptor Z
Raptor Z

Reply 10 years ago on Introduction

If its the circuit that too hard to design, you can leave out the relay, however the gun will miss fire. (see the two images below)
If your interested, I could document a simple on/off circuit with only 2 in-line switches.


Nicely done! The wheel drive is genius. Seems like there would be a way to feed the darts faster, but I suppose the slow fire rate helps to increase clip duration.

Overall this is possibly the most practical leggo gun I've seen that you might actually want to use in a battle.