M74DP Airsoft Gun Mounting Kit Assembly Guide


Tools Needed

  • Glue gun
  • Bandsaw, hacksaw, or dremel for cutting the gun casing
  • Large flat head screwdriver
  • small or medium phillips head screw driver
  • Wire strippers
  • Scissors
  • Wire cutters

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Kit Parts

1x b_500_500_16777215_00__images_assembly_M74DPhack_M74DP_PS.jpg

1x b_500_500_16777215_00__images_assembly_M74DPhack_Mount_Front.png
Front Brace
1x b_500_500_16777215_00__images_assembly_M74DPhack_Mount_Back.png
Back Brace
1x Pair Hopper_2.jpg
Front Bottle Supports
1x Pair Hopper_1.jpg
Back Bottle Supports
1x b_500_500_16777215_00__images_assembly_M74DPhack_Spacer.png
Spacer Brace Plate
1x RG Bottom Plate
Bottom Brace Plate - RobotGeek
1x AX Bottom Plate
Bottom Brace Plate - Bioloid
1x side bracket mounting plate - small
Side Bracket Mounting Plate - Small
1x side bracket mounting plate - large
Side Bracket Mounting Plate - Large
1x c Bracket
C Bracket
1x side Bracket
Side Bracket
2x sensor cables
Sensor Cable
1x power supply
7v 5A Power Supply
1x laser kit
1x RobotGeek Relay
RobotGeek Relay
1x Two Pin Cable
2 Pin Cable
1x Female Pigtail Cable
Pigtail - Female
1x Turbo Lock
Turbo Lock - 2ml

The following hardware is required to build the kit. You may have received extra parts with your kit. This list does not include parts for the Vision Tracking Kit or the Nunchuck kit (see individual steps for hardware parts list)

14x m2*5 bolt
Hex Socket Head Bolt
M2 x 5
16x bolt-m2-med.jpg
Hex Socket Head Bolt
M2 x 8
8x m3*8 bolt
Hex Socket Head Bolt
M3 x 8
8x m2*5 bolt
Hex Socket Head Bolt
M3 x 10
8x m3*14 bolt
Hex Socket Head Bolt
M3 x 14
20x M2 nut
Hex Nut
4x M3 nut
Hex Nut
4x m3*10 FF standoff
Hex Standoff F/F
M3 x 10
4x m3*20 FF standoff
Hex Standoff F/F
M3 x 20
8x m3*25 ff stanoff
Hex Standoff F/F
M3 x 25
4x m3*30 ff stanoff
Hex Standoff F/F
M3 x 30
1x 2 Pin Connector
2 Pin Connector

2x Wire Nut
Wire Nut

2x Rubber Band
Rubber Band

1x M3 Washer 8 OD 0.5 Thick
M3 Washer 8 OD 0.5 Thick

Pre Step: Peel Your Plastic

Some of your plastic pieces will have paper masking on one or both sides. Peel the masking paper off before getting started.

There also may be some dust on your parts. This is from the laser cutting manufacturing process. It is harmless and can be cleaned up by wiping with a rag or being washed with water.

Each plastic piece will have 2 sides - a matte side and a glossy side. When you're assembling your kit, the matte side should point up while the glossy side should point down.

Turbo Lock: Suggested Turbo Lock Use

  • Turbo Lock is provided with the kit. Due to the nature of the kit build, we do not recommend using turbo lock during the actual first build of the kit. Since there is adjusting and testing that needs to be done we recommend waiting until you have the kit completely built, tested, and working. Then if desired, it is recommended to take out one bolt at a time and add the Turbo Lock.

Step 1: Remove the scope pellet hopper

  • Use a flat head screw driver to pop the scope off the gun

Step 2: Saw off the tip and front sight

Img8093.jpg Img8094.jpg Img8096.jpg
  • Cut the orange tip off the gun and the front cross hairs
  • Scrape off the rough plastic edges with the edge of a flat screwdriver
BE AWARE - There are laws which state that every toy gun must have an orange tip. This hack requires cutting the tip off because it is glued onto the gun. To abide by your local laws you will have to replace an orange tip on the gun.

Step 3: Remove the six body screws

Img8098.jpg Img8099.jpg
  • Remove the six screws shown which hold the two sides together
  • Set aside three of the long screw. We will use these during reassembly.

Step 4: Open the casing

Img8102.jpg Img8104.jpg Img8109.jpg Img8112.jpg Img8148.jpg Img8113.jpg Img8116.jpg
  • Pry open the two sides of the casing. It helps to start with a large object inside the handle.
  • Work your way around the casing with a flat head screwdriver gently opening up the sides.
  • When you start to open the case it helps to slide a finger inside and hold the back of the air chamber down so that it doesn't spring apart.
  • If you do hear springs popping and parts moving around don't freak out. We will be taking everything apart anyway. Just be careful to not lose parts as you open the casing.

Step 5: Remove the trigger, trigger spring, and battery door.

  • Remove the trigger, trigger spring, and battery door as shown. You can discard these parts, they will not be used.

Step 6: Remove the DC motor and small gear

  • Remove the DC motor and small gear as shown. Set aside for reassembly later.

Step 7: Remove the air chamber and gun barrel

  • Remove the air chamber and gun barrel as shown. Set aside for reassembly later.

Step 8: Remove the three manual firing components

Img8163.jpg Img8166.jpg
  • Unscrew and remove the three parts indicated. You can discard these, they are not needed.

Step 9: Remove the backspin clutch

  • Remove the backspin clutch and spring. Set aside for reassembly later.

Step 10: Cut the rectangular piece as shown

  • Using wire clippers cut away the rectangular part as shown.

Step 11: Remove the large gear

  • Remove the large gear and set aside for reassembly later.

Step 12: Close up the case and make cuts

Img8178.jpg Img8178_cuts.jpg Img8181.jpg Img8217.jpg Img8225.jpg Img8226.jpg Img8182.jpg Img8305.jpg
  • Close up the case. You do not need to put screws back in during cutting.
  • Make three cuts along the dotted lines at the bottom of the gun.
  • Make sure that the cut for the trigger guard is flush with the casing. File or sand it flat if needed.
  • Cut the tabs off the top of the gun by the BB door. These interfear with adding the bottle hopper later. If you are not adding the external bottle hopper, you can leave the tabs on.
  • OPTIONAL: Some may choose to cut off the back end of the gun for sizing and weight.
  • When you reopen the casing make sure to vacuum or blow out any remaining plastic shavings.

Step 13: Prep the DC motor

1x sensorCable_150_70.jpg
Sensor Cable

Img8138.jpg Img8142.jpg Img8139.jpg
  • Note that the positive tab on the motor is the one with the grey wire and the dimple next to it. This is the tab you will solder the red wire onto.
  • Cut the ends off the sensor cable given. Then peal off the white wire and strip the ends of the black and red wires.
  • Desolder the wires off the motor and solder on the black and red wires

Step 14: Put the large gear and backspin clutch back in place

  • Put the large gear and backspin clutch back in place as shown. Don't forget the clutch spring.
  • Position the large gear as shown, with the non-geared section of the inside gears facing up toward the top.

Step 15: Put the DC motor and small gear back in place

Img8190.jpg Img8191.jpg
  • Place the DC motor back in place and then the small gear.

Step 16: Put the 0.5mm washer on

1x washer-m3.jpg
0.5mm Washer

  • Put the 0.5mm washer onto the post for the small gear. The washer comes with the kit and was not an original part of the gun. We add the washer to provide better gear meshing and to reduce gear stripping.

Step 17: Put the air chamber and barrel back in

  • Put the air chamber and barrel back in as shown.

Step 18: OPTIONAL: Put the hopper door in place

  • Only do this step if you intend to not add on the external bottle hopper later in this build tutorial.

Step 19: Close up the casing

  • Close up the casing with the three long screws saved from step 3.
  • DO NOT test your gun yet. You do not want to run the gun without the gun brace on. The brace helps hold the casing together tightly and keeps the gears from slipping. If the gears slip they can strip the teeth off and that is bad.

Step 20: Build the gun brace

8x m3*8 bolt
Hex Socket Head Bolt
M3 x 8
8x m2*5 bolt
Hex Socket Head Bolt
M3 x 10
8x m3*25 ff stanoff
Hex Standoff F/F
M3 x 25
4x M3 nut
Hex Nut

Img8222.jpg Img8220.jpg Img8224.jpg
  • Build the gun brace top section as shown.
  • Use M3*8 bolts for the four bottom standoffs and M3*10 for the top four standoffs.
  • Don't worry about positioning the bottle supports yet. You can adjust them later when mounting the bottle.
  • put 4 M3 nuts into the T-slots at the bottom.

Step 21: OPTIONAL: Attach the bottom brace plate to the C bracket

8x bolt-m2-med.jpg
Hex Socket Head Bolt
M2 x 8
8x M2 nut
Hex Nut

Img8228.jpg Img8227.jpg Img8342.jpg
  • This step is needed if you are mounting your gun to a pan & tilt system or tilt servo. If you are doing a direct mount with standoffs to a platform then you would skip this step.
  • Use 8 M2*8 bolts and 8 M2 nuts to attach the bottom brace plate to the C bracket.
  • There are two different plates. One which works with the RobotGeek C bracket and the other which is compatable with Bioloid brackets.

Step 22: Bolt the gun brace onto the gun

4x bolt-m3-long.jpg
Hex Socket Head Bolt
M3 x 14

Img8232.jpg Img8234.jpg Img8243.jpg
  • Bolt the gun brace together as shown using the spacer plate in between the top section and the bottom brace plate using four M3*14 bolts.
  • Make sure the laser mounting hole is facing forward.
  • The bottom plates have polarity, the side with the notch faces forward.

Step 23: Test the gun

2x Wire Nut
Wire Nut

  • Time to test the gun. Before we continue finishing the assembly we want to make sure the gun is working right. You don't need BB pellets to test. Just make sure the gearbox runs properly and starts firing.
  • You can make a temporary power setup by attaching the pigtail. Use wire nuts to join the red wires together and the black wires together. Plug in the 7V 5A power supply briefly to test.
  • The gearbox should run smoothly while the gun rapid fires. If it isn't working, take the case back apart and carefully check that everything is in place as it should be. Look at the photos in this guide for reference. Also make sure that you haven't wired the DC motor backwards.

Step 24: Set up the laser

1x 2 Pin Connector
2 Pin Connector

Img8237.jpg Img8239.jpg Img8247.jpg
  • Mount the laser in the front hole and push in tight. Then run the cable down the side and through the back hole as shown.
  • You will need to temporarily remove the standoff indicated to get the laser cable under it.
  • Using the 2 pin coupler connect the 2 pin extension cable to the laser cable. You can add some tape to secure the connection. Make sure the white wire (positive) is connected to the red wire.

Step 24: Sight and mount your laser

Img8251.jpg Img8252.jpg Img8253.jpg Img8254.jpg
  • Set up a testing station for sighting your laser.
  • You will need to power your laser. You can plug the laser into any "V" & "G" pins on the sensor shield to power the laser. (Red = V, black = G)
  • Power your arduino board with the standard 6V 2A power supply and the gun with the 7V 5A power supply from the kit.
  • It is handy to use a power strip with a switch on it to easily turn the gun and laser on and off while testing.
  • Set up a target to shoot at. A cardboard box with circles drawn on it about 20 feet away works well.
  • Adjust the focus on your laser by rotating the front piece until you have a nice sharp dot.
  • Load some BBs into your gun and fire at the target. Adjust the laser as needed until you have a good accurate sighting. The laser can be adjusted by pushing the back side up/down/left/right to adjust the seating in the hole.
  • Hot glue the laser in place. Also hot glue the back of the laser and cables to protect the wires from coming loose.

Step 25: Mounting the bottle hopper

2x Rubber Band
Rubber Band

Img8256.jpg Img8258.jpg Img8262.jpg Img8265.jpg Img8270.jpg
  • We now are going to mount our bottle hopper. We first need to get everything positioned right to determine where to cut the hole.
  • Strap the bottle into the brace with the rubber bands. Loosen and adjust the four bottle support brackets until you have the bottle positioned how you want it.
  • The bottle support brackets should be positioned so that the curves are flush against the curves of the bottle.
  • The front of the bottle should be higher so that the bottle is tilted backward which will feed the BBs into the gun.
  • Position the bottle so that the curveed edge at the top rests against the circular gun hopper opening.
  • Use a marker to trace the circular opening onto the bottle
  • Using scissors cut the circle into the bottle. Be careful to not make it too large. You want a snug fit.

Step 25 CONTINUED: Mounting the bottle hopper

Img8272.jpg Img8273.jpg Img8274.jpg Img8276.jpg
  • Reseat the bottle back onto the brace.
  • Most people will have to readjust the bottle supports to lower them so that the gun hopper opening fits up into the bottle.
  • We recommend using hot glue to seal around the hopper opening and along the bottle supports for added reinforcement.

TIPS: Filling the hopper

  • When filling the bottle hopper it is not recommended to fill it all the way if you are mounting the gun on a RoboTurret. A completely full bottle can weigh too much and over stress the servos. About half full is a good guidline to follow.
  • It is also recommended to only use .12g BBs.

Step 27: Wiring

gun-setup.jpg gun-setup-cu.jpg roboturret-gun-setup.jpg roboturret-gun-setup-cu.jpg Img8291.jpg laser-on-signal.jpg
  • The first two diagrams are for the basic wiring of power, laser, and relay.
  • The next three are for mounting to a RoboTurret.
  • The final diagram shows how to wire the laser to signal if you choose to turn it on/off through code.


10x bolt-m2-short.jpg
Hex Socket Head Bolt
M2 x 5

  • Mount the gun to your project!
  • If you are mounting to a turret or pan and tilt system use 10 M2*5 bolts to mount the C bracket to the servo.

MOUNTING OPTIONS: Deck Mount with Tilt Servo

4-14x bolt-m2-short.jpg
Hex Socket Head Bolt
M2 x 5
4x M2 nut
Hex Nut
8x m3*8 bolt
Hex Socket Head Bolt
M3 x 8
4x m3 FF standoff
Hex Standoff F/F
M3 x your choice length

Img8337.jpg Img8310.jpg
  • Shown with deck mount and a tilt servo. (No bottle hopper)


8x m3*8 bolt
Hex Socket Head Bolt
M3 x 8
4x m3 FF standoff
Hex Standoff F/F
M3 x your choice length

  • Shown with direct mount and no bottle hopper.
  • For direct mount you will not use the C bracket and use 4 standoffs with a height of your choice.


PC Control These demos and projects allow the robot to be controlled via a computer.

ArbotiX Commander Control - These demos and projects control the Robot using the ArbotiX Commander, the handheld Arduino based remote control.

Direct Control - These demos and projects control the Robot directly from sensors connected directly to the Robot's control board.

Pose Control - These demos and projects allow you to create and playback a sequence of poses.

Serial Control - These demos and projects control the robot using a serial packet protocol.

Standalone - These demos and projects are deisgned to let your robot function without a computer or additional microcontroller.

Wireless Control - These demos and projects allow you to control the robot wirelessly - usually by replacing the Serial Connection with XBee modules.

Reference - These articles have technical details regarding the control and operation of the robot.


More info here

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