Custom Made Systems for the NERF Crossbolt

The NERF Crossbolt, a blaster whose design everyone liked, but hated for its performance.
Darts will always get chewed up and the Rubber Band always tend to "jump" above the dart, causing jams.
The internals is rather complex and it requires the string to go under the dart. modifying this blaster is not only difficult, it is also unreliable as it will cause it to malfunction easily.

 Internal shot of the Crossbolt

Then, there is the NERF Stryfe. A favorite with Nerfers all around the world.
Loved for its Simplicity, Reliability, Rate of Fire and Performance, there is hardly any games that this blaster isn't being used.
Modding capability is rather easy for this blaster, with aftermarket part makers creating various kits for performance and aesthetics.
because of the simplicity, you hardly ever find the blaster malfunctioning during games.

Internal shot of the Stryfe

The Kriss Vector Kit,

one of the most popular kits for the Stryfe

This project is aimed at creating and improving the function of the Crossbolt, without changing the look of the blaster.

Initial design process thinking:
during the initial design phase, I wanted to go with the same lever mechanism that the Stryfe used.
However, looking at the compact size of the Crossbolt, I figured that an electrical system would be more compact and with the possibility of it become fully automatic.

An example of the layout

Design and trial phase:
A custom project usually means there aren't any parts readily available and a considerable amount of design thinking is required.
The first design problem I tackled was the design of the flywheel cage.
Initially, I went with a simple cage design. For the cage to hold the motors and wheels, nothing else.
but after considering the previous experiment regarding spinning darts increasing stability, I decided to add a 10-degree angulation on each motor post.

The original flywheel cage design

The beefier canted cage design

The canted flywheel cage

Next was the pusher mechanism.

I reused an electronic gearbox from another toy I had lying around and used that to push a "slide", which will be pulled back by a spring. However, because the blaster is a bullpup design, I had to figure out a way to push the dart into the flywheel cage, while the gearbox is seated at the front.

in order to hold everything in place, I made a jig to secure the slide, spring, and gearbox in place as I do not wish to glue them in. This is so that it will be easier to upgrade this in the future as everything is held in place purely by fitting and tolerance.

A small hook was added to the slide to accommodate the spring

The pusher mechanism jig designed to house the spring, slide, and gearbox

I cut and bent a hanger wire into a "hook" to be attached to the slide in order to pull the dart forward. However, it wasn't going far enough to feed the dart into the flywheels.

To remedy that problem, I designed a tip to be placed onto the end of the "hook" so that it will push the darts better and further.

Glue was added to fill the empty gaps between the wires at the hook end

The pusher tip is rounded at the tip to facilitate ease of feeding the next dart

Testing out the pusher mechanism

Testing out the pusher mechanism (Slide and spring)

Switch Placement!

The last few touches before we can close the shell up.

2 switches are required to run the blaster, a flywheel switch, and a pusher switch.

I used Omron switches, a small 5A switch for the pusher mechanism, and a larger 15A switch for the flywheel switch.

The reason for 2 different switches is because the pusher mechanism only have one motor, while the flywheels have 2. this would mean higher current will be drawn by the flywheel system rather than the pusher mechanism

The other reason is because the trigger has space for a spring to push it back, but the flywheel switch is too small to accommodate a spring, therefore it uses the spring from the micro switch to push it back.

Example for switch placement

Handle Jig made to hold the micro switches and triggers

The flywheel switch trigger

Prototype testing phase

some shell trimming was required to close the blaster nicely, but finally, the 1st prototype of the design is complete.

the power source I have available (Li-ion batteries) is insufficient to power the blaster properly but is capable of powering it up for a short time, enough for me to test it out.

Prototype internals of the project blaster

the blaster with both side of the shell closed, motor covers, and a makeshift power source

After closing it up, and wiring it up to a makeshift power source, it was finally time to test it out!

watch the video below!

Test firing to see if it will actually fire darts.

While the blaster is capable of firing darts and served as a proof of concept that it would work with enough design thinking and brainstorming, it is currently not practical for use in a game due to many reasons.

1) Lack of a proper power source

This means that the blaster is severely underpowered and the clunky taped-together power source makes the entire blaster very clumsy.

2) It's not finalized

For obvious reasons, you don't bring a prototype design at the initial stages to the field to test it out, especially at the current state of the project

3) More tweaking is required

The blaster still faces a lot of issues from time to time, such as the flywheels not staying in place or the motors shifting around.

So now, while the prototype is completed, further improvement is needed in order to turn the blaster into a capable blaster worthy of seeing Nerf games.
It has been an overall fun project, and I already have people messaging me on facebook, asking me to built this for them or if I will be making a kit for the blaster. sadly I had to turn them all down as I can't possibly bring myself to give them an incomplete project.

Till next time, 
Flechette Spectre

Scavenging old parts for newer blasters

Long ago when nerf modding was rather new, and there weren't much aftermarket part makers, one company stood out.

ORANGE MOD WORKS

The first company to offer metal internal kits for various blasters, the OMW Metal Recon kit was notoriously famous for making your blaster hit further, harder, and not breaking apart.

However, as the technology for nerf blasters improved, the OMW Metal Recon Kit is now considered obsolete, to the point where a slightly modified blaster and outperform a heavily modified nerf recon with metal internals.

In the spirit of old school modding and the fact that I don't have the money to buy new stuff, I decided to try and salvage some parts from an OMW Metal Recon Kit which I have in my possession.

 Steps to update the old metal breech.

1) Cut out the "stem" from the breech

2) chamfer the back end and smooth it out with sandpaper

3) mark out where the O-Ring(s) are.

 Be sure that the upper ring is the same position as the stock breech.

4) Cut out the O-ring slots.

With that, you will now have a new breech that is made of metal.instead of plastic.

 This will help the breech withstand harder impacts from higher spring loads as well as improving the internal aesthetics of your blaster (cause metal is more "bling bling")

The breach sitting in the Nerf Retaliator, with a metal bolt sled.

solving a problem with nerf darts.

A common problem with Nerf darts being shot from a modified Nerf Blasters is the inaccuracy and instability of the darts in flight.

Darts tends to "fishtail" in mid-flight. this is partly due to the design of the darts, and the way it fires.

Unlike modern firearms that have rifling within the barrel, which provides a spin to the munition that they fire, thus increasing the stability of the projectile in flight, making it more accurate.

Nerf blasters lack any rifling at all, similar to smoothbore muskets in history. coupled with the poor design of nerf darts, makes it pointless to have a powerful blaster. unless you can improve the stability of the darts in flight.

Quite awhile back, Nerf community members have found that by reducing the dart down to 3.5 cm, it would reduce air drag on the dart and make it fly further with a slight improvement to accuracy.

But darts still aren't hitting their target consistently and fishtailing, although reduced, is still a problem.

so, to reduce the fishtailing effect on the darts, I decided to try my hands at making a barrel attachment that will induce a spin to the darts, enough to improve its stability in flight and thus reducing or eliminating the fishtailing effect.

initial attempt:
muzzle attachment - 0.5mm rifling
blaster - retaliator with artifact punisher kit, 8kg spring

 Results:
Significant increase in accuracy with a slight drop in range.

Possible Reasons:
The rifling helped induced a spin to the darts, hence stabilizing the dart in flight.
OR
the rifling reduced the dart's velocity due to friction and made it less prone to fishtailing

second attempt:
muzzle attachment - 0.75mm rifling
blaster - retaliator with artifact punisher kit, 8kg spring

Results:
Slight increase in accuracy with a severe drop in range.

Possible Reasons:
The rifling was too thick and induced too much spin due to friction from the rifling. this reduced the velocity too much and cause the dart's range to drop severely.
Would need a stronger spring if this was to work better.

Another thing that I tried was to use the darts own tip to induce the spin. I tried designing a dart tip with little notches at the side to induce pressure and spin the dart.
will need excessive testing and most likely would do a CFD test to test our the design (that's for next time)

Prototype dart tip design