For those looking to utilize a handheld MAC cannon to launch tungsten rods at hyper-sonic speeds.
Full description and file set available on the main product page.
The Railgun features a functional cartridge loading mechanism with multiple payload options. There is a functional trigger system connected to pneumatic payload delivery system. There are several cavities for lights and multiple build option to help increase structural integrity in with stylized struts.
This Build Guide will list the following:
Required materials to complete the project
Assembly videos to walk you through the assembly process
Recommendations for Print Settings/Orientations for certain pieces
Any additional questions you have concerning the building of this model can be sent directly to me via the contact page on my website
Build Requirements
A 3D Printer with a 350 mm build height.
(Printers with 300x300mm build plate can also print the pieces if aligned diagonally. Print Settings/Orientations/Tips were created assuming a vertical orientation of most of the models and this will require at least a 350mm build height.)
Rubber Bands
Pneumatic Assembly Components (Optional)
(the Drain Gun comes with 5 20g charges, 12g C02 cartridges are much more common and also fit the drain gun if a little padding is used (toilet paper for example)). It also uses the cheaper, unthreaded canisters
A soft Gasket such as an EVA Gasket. I used a 12x17.5x2mm Gasket that came from a set from Harbor Freight
Electronics (optional)
LED String Lights
(Remote Controlled may work best, but there are removable ports/panels for you to access the lights whenever required)
Assembly Instructions:
Railgun Assembly
The video below contains written text to illustrate how to put together the base railgun. I included a number of tips below the video that I learned while assembling the gun myself.
Note, that when assembling the core body. The trigger guard and Core Body C, close around the Trigger to give it a closed cavity to slide within. The C02 trigger acts as the spring for the trigger, so it that is not desired to be included, you can include a small spring behind the trigger within the grip.
Most of the Core Body Accent pieces can be included during assembly, but Accent D needs to be attached last in order to not block the Stock frame from sliding over the Core Body Stock.
While not shown in the video, there are separate versions of the Core Rod that fit different versions of the optional struts/teeth. If these optional methods are utilized it is recommended to attach the Core Rod, struts, and Core Body B, before sliding it into the rest of the Core Body Assembly.
When Assembling the Core, you should hot glue the trigger mechanism of the Drain Gun into its slot, but do not yet attach a C02 core. The trigger mechanism needs to be glued in place so the trigger does not push it out. Additionally, attach C02 canisters should be done last as it can get in the way of some of the pieces during assembly. It can be screwed in place last via the C02 entry port.
When assembling the Stock, the Release Mechanism should use a very strong rubber band. When I assembled mine, I wrapped my rubber band into 4 loops to make it very strong. The Release Mechanism pulling back into place is what keeps the Ammo Counter and the Cartridge in place when everything is pulled down. In order to avoid gaps showing in that configuration, the Release Mechanism has to pull back hard on the hook on the Ammo Counter. Additionally, the Release Mechanism Cover should be held in place with hot glue. This will hold the cover firmly down on top of the Release Mechanism such that it only slides back and forth and does not get pulled up by the ammo counter, which can also lead to gaps. I used Hot Glue as it allowed me to still be able to pull off the Cover later in the event of needing to access the robber bands. Be careful to not accidentally glue the Release Mechanism when doing this as you need it to be able to slide freely. The Release Mechanism Buttons can be attached last so that you have a way to slide the Release Mechanism and eject the cartridges.
The highlighted area is where the rubber band needs to be placed.
The Stock Frame Extension can be super glued to the Stock Frame. These were only done as a separate piece in order to help the stock frame fit most printers.
All External Jacket A pieces can be super glued to their B pieces, these seams are only there as the pieces were too large to include as singular pieces.
There are two notches on the Cartridge Lever for a singular rubber band to connect to. This rubber band needs to sit inside one notch, go through the two slots on the Cartridge Entry Port and then connect to the second slot on the Cartridge Lever. This needs to be done prior to the Cartridge Lever connecting to the Cartridge Entry Port and being held in place by the Lever Pins. *See the Video Below
Lever Pins should be glued in place, or can be duct taped in place so that they can be removed if a rubber band placement is required
The Cartridge Sled is set down with in Core Body C and held in place by the Sled Clip. This allows the Cartridge to rotate upwards while staying secure in its housing.
The Sled can now have a rubber band looped around its hook and the hook in Core Body C, this will ensure that the default position for the sled is "up". When the ammo counter is rotated downward and hooked onto the Release Mechanism, the Cartridge Lever will push down on the Cartridge in the Sled and force it down into place.
If everything is assembled correctly, it should move as smooth as this
In the Core Body Stock, there is a small circular housing for a gasket to press up against the back of the Cartridge/Cartridge Core when everything is loaded and locked in place. This will ensure an air tight seal and allow the C02 to push the payload out of the Cartridge.
There are two compartments that can be utilized to house any LED's/electronics you desire. See highlighted portions below
They can be accessed two different ways, there is a battery port access panel that can be removed to access the lower core.
There is also several large openings in the top of the core that can be accessed if the top external jacket is removed. *removing the loading mechanism is required to remove the external jacket as well.
Below I've included a picture reference on everywhere to put the screws. The screws are highlighted magenta.
Cartridge Loading Instructions
The payload cartridge is standardized, but the cores can differ depending on what you want to fire. The first image shows the airsoft core. In this configuration you should take the body of a nerf dart and cut the tip off such that the foam body remains measuring 60mm in length. This should be inserted into the body of the core to act as a sleeve that holds the BB's in place. You can then place the airsoft core tip. From here on you can front load the BB's.
For the Nerf Core, it is designed to be a snug fit for the dart so the build up of pressure releases the dart. There is a printable dart that also easily slides into place if that is desired.
General Printing Tips
Most of the pieces were designed to be printed in a vertical orientation. Special consideration was made to ensure the least amount of supports necessary when printed this way. However you decide to print the piece, make sure to calibrate your XYZ steps on your printer before printing!!
Because this print is so large, any mismatch between the X Y and Z axis accuracy can add up to 1-2 mm of error over the whole ~4ft print. This can be avoided by calibrating your XYZ steps on your printer. To get the best accuracy for this test, I would recommend print your calibration cube at the largest scale that your calipers can measure. For example, getting a 60mm cube within .01mm of accuracy is going to be more accurate than getting a 20mm cube to that same .01mm of accuracy. Additionally, printing a majority of the large components in the same orientation will ensure that any errors still present will be in the same direction and you are less likely to see any gaps as they cancel themselves out.
The pieces are not pre-oriented so you will have to adjust them to ensure they are in an orientation more optimally for printing (flat surfaces touching the build plate). Additionally, for pieces that have no ideal flat surface, I highly recommend using the Cylindric Custom Support downloadable plug-in for the Ultimaker Cura Slicer. It allows you to place custom supports on parts to ensure that you can get much safer and reliable prints on parts with odd geometries. Some of the examples below will show these custom supports, you will need to add them, or something similar to your own prints. These supports will also allow you to add more stable bases if your printer is not great at printing tall thin objects. Similarly, I would recommend using a 10-15mm Brim to ensure good build plate adhesion.
Optimal Print Orientation
Load Bearing Pegs/Pins
All Pegs/Pins should be printed such that the layer lines align with the long axis of the pin, this will make them much less likely to snap off within the pieces due to any bending force.
General Print Orientations
I've combined multiple files into one build plate in order to show multiple orientations at once, I do not recommend printing multiple pieces at once as it will increase overall print time due to excessive travel time, and introduces multi-print failure risks.
In general if you see any circular or semi-circular arcs on any of the prints, you can place a support blocker to reduce the overall number of supports. Arcs like that are typically self supporting and print find without supports.
As you can see, most of the Core Body pieces are meant to be printed vertically. Most of them are pretty straight forward, but the trigger guard will likely require the most supports.
Additionally, with these Core Body pieces, they are designed to be printed vertically. Some additional notes for Core Body C, is that there is a thin wall over hang that I recommend placing some thin custom supports so that it is not just supported by an auto generated thin, singular wall.
For the Stock components, the only main structural piece is the stock frame itself. The stock pad, doesn't have a great option for orienting, so I printed it on its side. The Stock Accent Panel B is printed vertically because it does have a conic cavity on its large flat face to give extra space for the C02 Cartridge. If printed flat, the supports would be annoying to deal with depending on your support settings. Its not a big deal either way. The C02 access panel and the Release Mechanism Cover are printed vertically to minimize supports and reduce the risk of rough support touching surfaces have to fit together during assembly.
Which ever Core Rod option you pick, I recommend printing them vertically to ensure it more easily slides into the core body. The Peg is printed such that the layer lines are longitudinal and reduces the risk of snapping the peg within the Core Rod.
Most of the External Jackets can be printed close to vertical. Lower Jacket B is printed at a slight angle so that the front face is flush to the build plate. This configuration minimizes the amount of supports used as opposed to using the perfectly flat sliced face. The Lower Jacket A can be printed vertically but will have lots of supports, it can also be printed flat as shown, but remember you run the risk of it having some friction when trying to put it onto the Core Body if your X/Y axis is not calibrated extremely close to your Z axis.
For the Loading mechanism, the lever should be printed with its flat face touching the build plate. This ensures that the bending force from the rubber bands are less likely to snap the piece. I have the ammo counter's hook flush to the build plate and added some manual supports on the side to ensure it prints well. This ensures that no supports are needed inside of the Ammo Counter Cavity and vastly reduces supports needed. I printed the Cartridge Sled vertically so that the walls that the Cartridge slides along are support free and smooth.
Lastly, All of the Cartridge pieces are designed to print well vertically.
If you have any additional questions, feel free to contact me!
Personal Build
I had such a fun time building what is one of my favorite guns from the Halo series! I included a video of my live fire test, showing both foam darts and BB's in action! Let me know how your own builds go and if you have any questions!
