the old v4

This is an improved, simplified version.  It features a 2 way solenoid to shoot.

depending on how highly its pumped up, this can be VERY powerful

Cascading QEV blaster piloted solinoid. Custom 3D printed body with single shot bolt action breech.  17/32 brass as barrel.

1. Create as many parts as possible using a consumer grade desktop 3D printer with common materials.
2. The blaster should be durable enough to last through years of hard play with minimal or no maintenance.
3. Maintain the performance characteristics of the classic Rainbow
4. Improve on the ergonomics of the Rainbow
5. Create manufacturing jigs to aid in the easy fabrication of non 3D printed component

The current source models contain files for a full and half length Rainfaux pistol. The full length is a highly performant blaster, capable of 300fps velocities, and the half length is only slightly less capable. I'm working on the pump-action and DCIT version of this blaster next. My two prototypes have been war-tested a couple of times now, but long-term testing is necessary.

PROJECT FILES ARE HOSTED ON PRINTABLES

Bill of Materials

• PLA Filament
• TPU Filament
• 14" of 1.25" PVC
• [[[[k25]]]] spring
• qty 2 1/4-20x1" screws
• qty 7 M3 x 10mm screws
• qty 1 M3 x 15mm screws
• qty 7 M3 square nuts
• qty 1 M5 x 15mm screws
• qty 1 M5 hex nut
• qt2 4x2mm magnet
• ballpoint pen spring
• AR compatible grip (a printable reference grip is included)

Assembly

Use drill_guide as a guide for drilling the holes in the PVC for the catch. An 1/8" drill bit will give you clearance for the M3 screws. The hole under the catch itself will need to be at least ¼" to accommodate the catch screw. 

Not all PVC is the same size, so it is possible you will need to use diameter_gauge_1.25PVC to figure out if the parts need to be resized. 

Use silicone grease on the plunger head to ensure a low friction seal.

The catch uses two 4mm magnets which should be oriented to repel each other. The trigger and grip have retainer holes for a small pen spring.

This is going to be my attempt at making a "modernized" version of the ESLT mechanism. 

For those who (somehow) don't know about the ESLT, here's the most recent thread about the blaster: http://nerfhaven.com/forums/topic/25786-eslt-16-instructions/

My "modernization" of the design aims to keep the same aesthetic and roots as the original, while improving on durability, printability, sourcing of parts, and bringing in a bunch of modern quality-of-life features. A lot of stuff has been learnt (collectively by the community) in the more than 10 years since the original ESLT.

Currently planned or implemented features/improvements:

• Updated more modern hardware standards that are easier to source from modern hobby shops (OutOfDarts, SilverFoxIndustries, etc)
• More durable printed parts
• Better printability
• Better air seal
• Ability to swap between Talon mag feeding or Hopper feeding
• Quick barrel swapping and better barrel retention
• More comfortable stock and grip
• More reliable catch mechanism
• Lighter trigger pull
• Improved pump grip, and several pump grip options to choose from (Picatinny rail, original style, modernized angled grip)
• Easier swapping between extension spring and latex/elastic setups (also possibly compatibility with "normal" compression springs such as [k25] or 788)
• Sturdier overall build quality
• Lighter
• Adjustable stock / length of pull
• etc etc etc

These changes should be relatively easy to pull off with modern techniques, while still keeping the original soul of the design, both aesthetically and mechanically. 

I don't plan to update this thread as often as I do on Reddit/YouTube/Discord, but expect an update every few months or so until the design is finished.

-Sillybutts

This is Project 13. It is a brushless, stepper-bolt-driven, fully automatic, mag-in-grip pistol.

The flywheel system is built around EMax RS1108 4500KV motors. It is a Hy-con derived (circular gap) profile of 29.5mm wheel spacing and 9.0mm gap. It hits around 120-130fps with Worker Gen3s, although I’m pretty sure the long bore is interfering with the darts since just the cage was doing about 140.

The pusher is a scotch yoke of 24mm stroke driven by an OMC 17HS08-1004S stepper motor and it is currently set at 8.3 darts/second. The 24mm stroke is kind of borderline with Worker Gen3s and may run into issues with 36mm darts if there’s a decap and the foam gets left behind.

The magazines are printed and are unique to this blaster, but they are very similar to angled Talons and with some modifications to the blaster I think it could take Talons.

The blaster is 246mm long and 157mm tall from the bottom of the grip to the top of the rear irons. The main body is 40mm wide, with the stepper poking out to 42.3mm, and the flywheels going out to 58.5mm. The last 26mm on the front are purely cosmetic to taper the profile down slightly. You could easily take that off and print a square-nosed version that would remove that length.

There is a detachable stock that is held in by two pins at the bottom and a spring latch at the top. These pins are 6-32 screws cut down, ground to shape, and press fit into the stock base. To remove, press the latch and rock it back slightly until the latch clears, then slide the stock mount downward. Stock is sized for 3/4” SCH40 PVC.

The rear irons are removable, partly to facilitate printing, and partly to allow for other options to be installed. I CADed a picatinny option, but haven’t actually built it.

The battery is a Lumenier 550mAh 4s lipo.

https://www.getfpv.com/lumenier-550mah-4s-80c-lipo-battery-xt-30.html

The ESCs are ZTW Spider 12A, modified with a tach wire for feed control, an upgraded DC link capacitor (Rubycon 25ZLQ180MEFC6.3X11) which has been hooked up perpendicular to the board’s long axis to shave a few mm of length. The motors are wired directly to the ESCs, without connectors, to save more space. The blaster’s main PCB is a custom unit. It takes an Arduino Pro Mini and a DRV8825 carrier board and features headers for the ESC signal cables, trigger, and bolt limit switch, but no other controls. I had to use short headers to fit the connections under the top cover. This board is also used for power distribution to shave a little space and not require splices in the wiring. Battery lead goes to one of the two sets of holes on the side, and ESCs get wired directly to the other sets (ESCs go on the symmetrical pairs). There is bare copper on both sides of the board so you can dump solder on the pad or add bus bars for Vbus and GND. Remember to put something on the board to insulate these bare areas.

The trigger switch is a full sized microswitch, with the solder tabs cut way down so it fits between the trigger and the magwell. I also cut a notch into the top corner of the body to pass a wire through.

As with a lot of my recent work I should credit torukmakto4. While this shares no parts with any of his designs, many of the ideas have root in those designs. This obviously looks a lot like the ACS but much of that (though not all) is convergent evolution, not direct inspiration. And the software is largely his work as well. Also thanks to Matthew Bregg for bringing the ZTW Spider 12A to my attention.

CAD, firmware, and Gerbers in https://drive.google.com/drive/folders/12NnNsQ9Sof8Ix1VdAmZnOsNNKaHzfIv5?usp=sharing

Filaments are Overture magenta, Esun white, and Yoyi transparent violet. The magazine pictured is Overture transparent with a magenta follower.

Errata and other notes:

- The file I provide here for the upper is what I printed, but it required rework after the fact. It needed to have some deeper pockets cut into the corners of the stepper recess to fit it.

- I forgot to add a pocket on the stock base for the latch spring to match the pocket in the latch. I just drilled a hole here on my printed copy.

- Most screws are 6-32, with a couple exceptions. Motor screws are m2, stepper mount screws are m3, there is an m3 in the mag release due to space constraints, and there is a 4-40 set screw in the crank for the same reason.

- The spring on the stock latch was taken from my parts box so I have no part number to provide.

- I can confirm bs_nfet firmware on the 12A version of the ZTW Spiders, and also that the portable chromium install and rapidflash method that Matthew Bregg detailed at https://torukmakto4.blogspot.com/2021/01/flashing-ztw-spiders-for-flyshot.html works for them.

- In the one game I used it in so far, it was horribly inaccurate, although I’m not sure how much of that was the blaster and how much was the darts (used Worker Gen3s), or me, or the 20mph wind that day. This may be the bore interference again.

- Some more notes on the magazines: As I mentioned they are very similar to angled Talons. I originally intended this to take angled Talons but as I thought about it I realized I’m designing this blaster for me, not anyone else. I don’t already have an infrastructure around angled Talons and would be printing my magazines anyway, so I felt comfortable making more changes than I originally planned. These magazines have the same overall external dimensions, although they’re just rectangles and don’t have the notches on the front and back that angled Talons do. And because they print outsides on the bed the feed lips don’t protrude beyond the body dimensions. The front edge just under where the dart gets pushed out is slightly lower down here to accommodate a bit of flywheel cage geometry. And finally, they have a front catch notch. To make this blaster compatible with angled Talons, the following changes would need to be made:

• Pocket out the opening to allow the feed lips to fit. I don’t know what this would do for strength.
• Remove the offending geometry from the flywheel cage area on the lower or alternatively grind that part out of the magazines.
• Make some sort of rear magazine catch or add a front notch to each magazine.

A while back I was looking at Domochevsky’s Rail Cleaner. If you’re not familiar, it’s a flywheel revolver with shells that feeds a cluster of 4 darts into a set of very tall flywheels to fire all four at once. I thought it was a neat design, but that it had some glaring flaws:

- It was closed source (sort of).

- It used DC motors.

- It was not fully-automatic.

So I set out to fix them. Initially I entertained the idea of keeping the Rail Cleaner layout, putting some brushless motors in, and automating the feed with a stepper or something, but was not confident in reliably advancing and stopping a large, heavy cylinder. I next considered mag-fed and still feeding from shells, and was thinking of ways to eject the shells automatically when I had a eureka moment. I realized I didn’t need to use shells if I could feed a two-wide stack of darts in a magazine and strip two rows off the top with each shot.

A prototype magazine literally made out of cardboard and hot glue proved the feasibility of the magazine and a printed magazine and flywheel cage followed. At this time all that remained was building the full blaster.

Before going too deep into the mechanicals though, A little bit on its performance. Velocity is ~95fps and it’ll do about 7 shots (so 28 darts) per second. It’s weird about darts. It’ll fire basically anything, but waffles and blue/green sureshots yaw sideways *hard* as soon as they exit the barrel. Elites and ACCs don’t, but their aerodynamics are crap so it kind of doesn’t matter. I suspect what’s happening is that as the darts are leaving the flywheels, the sideways loading from the flywheels at the back of the darts forces the darts to yaw (lay a couple darts next to each other on a table and press two flywheels against them near the tail to see what I mean.) at which point the heads drag against the control bore asymmetrically and the drag on the outsides forces them out at an angle. This at least partially explains why narrow-headed darts aren’t affected – only foam contact on the sides means less friction, but that doesn’t explain everything. Accufakes sometimes shoot straight and sometimes don’t. Adventure Force max accurate don’t work super well despite the narrow heads. Testing with menguns that I accidentally ended up with after thinking I was buying brick tips is promising.

Errata: The flywheels are a pain to print due to the steep overhang and mine came out quite rough there. The groove fillers are also *very* close to the wheels, so sanding may be required to clean up the flywheels, the cage, or both.

I went with using the T19 drivetrain stack for all the parts that weren’t unique to P16 since I liked the ergonomics and functionality and couldn’t be bothered to custom design an entire blaster when the core of P16 is just a magazine, breech, and flywheel cage. To that end, the grip base, grip frame, grip panels, trigger, magazine catch (use the full length one), drive housing, drive spacer, drive cover, crank, crank pin bushing, stock base, stock, stock pad, and velocity and selector knobs could all be unmodified T19 parts. P16-unique parts are therefore a breech, bolt, flywheel cage main and cover, flywheels, ESC covers, muzzle device, and rail segments. I kept the T19 knurled styling for the new parts for consistency, and because I found I actually quite like the way it looks. I did use the modified velocity knob, grip frame, and stock base as described in my MEGA T19 po  st here, although this blaster predates that one, so this was actually the first use of those modified parts.

I changed the full-auto operation of the bolt for reliability reasons. Rather than the bolt motor spinning at a constant speed, it moves at full speed for one cycle and then stops before pausing and starting again. This means the bolt stays back longer allowing the darts to rise up in the magazine.

More about the magazine: it uses some design ideas from torukmakto4’s rapidmag heavy. The dovetail pattern between the two halves have some notches that take a decent bit of force to snap together, but hold together with no hardware or glue. Only tested with petg and the deformation required to get these together might cause pla to just break. Even some brands of petg, like yoyi, have had dovetail teeth snap off. Overture has been fine though. If you need to get them back apart, I’ve had success seperating the halves by pulling the front and back apart at the open top end to make a gap in one or two dovetail sets, then working a small straight blade screwdriver in the slots and progressively moving down the magazine.

Filaments are Snolabs Reicher blue, Makeshaper white, green, and transparent orange petg, and a tiny bit of overture white tpu on the grip scales. That tpu really doesn’t do much. It feels different since it has that characteristic rubbery texture, but it doesn’t squish or anything, at least not with only 1mm of it. Motors are Turnigy V-Specs since I still have a decent stash of them.

Files at https://drive.google.com/drive/folders/1ztNHMAmngPhrtpNzEa59cV4vzmRsv9vP?usp=sharing

A look down the back of the flywheel cage at the wheel geometry:

A shot of the new larger bolt face:

Magazine:

Magazine dovetail closeup:

EDIT: Firing video

The SuperSledge is a full recreation of the Nerf SledgeFire, but improving it for NIC use in every way. Larger plunger tube, stronger springs, community designed shells (Spring Thunder right now, more later), quick takedown functionality, quick barrel, stock, spring, and ammo type swapping (no screws, all takedown pins), and the whole blaster uses easily accessible hardware and pretty simple 3d prints. 

The only spring in this blaster is a chunk of [[[k25]]] for the plunger. The catch, trigger return, priming lever return, and ejection are all covered by two pieces of elastic cord. The top barrel locking lever uses a rubber band or hair tie.

The barrel and stock can be easily removed, with two takedown pins for the barrel, and one takedown pin for the stock. The ammo type can be swapped quickly with a swap of the barrel and breech face, only three takedown pins. The spring can be swapped easily as well, with only three takedown pins removed. All able to be done at a game, maybe even on the field if you wanted to.

Here are some development photos: 

I started out by doing a straight 1:1 sketch of my SledgeFire's internals.

https://www.youtube.com/watch?v=OJQCfiQKtqw

I also took some video of the SledgeFire's internals, just to work over them in my head.

This is where the 1:1 sketch ended up after some refining.

Here you can see that I have removed the trigger lock and fleshed out all the internal components. There is a rudimentary priming pivot, as well as more properly sized levers and bars. I have also added a segment of FLAK 2"OD plunger tube and begun work on a plunger.

The first side panels are now in place! Lots of small tweaks were made to all the internals, tweaking thicknesses and lengths. The catch is now properly supported, there are spacers to keep the internals centered between the side plates, and the plunger has been simplified. The priming lever is now an actual lever. There is a small dingus on the back of the trigger used for attaching an elastic through the catch, but it was pretty quickly removed in favor of a simple hole through the whole trigger.

https://www.youtube.com/watch?v=UtcTChv5F5E Video overview of the design so far.

This was the point where I made my first test print, just to check internal functionality and printability. There were definitely tweaks to be made to improve reliability, but this was when I was 100% sure that this concept could work in the real world, not just in CAD.

https://www.youtube.com/watch?v=8y1QMHJ7zKs

This is where I began modeling the grip. I used the basic thickness and length of a v4 Caliburn grip, but that didn't last for long as you will see next. You can also see that the internal spacers are now small discs instead of larger parts. There are now also connection blocks and a bottom cover.

Here I've begun to smooth out the edges and corners of the side panels. The top-back of the blaster now has nice covering plates. The grip has also progressed into it's basic final design, split into 3 pieces; a core and two side panels (SpudSpudoni helped me a bit with figuring out the Fusion tools to make the finger groove curve near the trigger well. Thanks Spud!). There is now a shell storage stock as well.

Barrel! The shell ejection mechanism can be seen much better in the next image. You can see the stock lug now too.

https://www.youtube.com/watch?v=R51Mks6aqek I also did another video overview around this point.

Lots of work around the plunger tube. The breech face is now thicker and locked in place with a top strap and a takedown pin. The barrel latch is now also in place.

And here is the current design! Lots of small tweaks to parts, lots of smoothing and print optimization. Previously, some parts were just floating in place. Now, all the screws and connections are modeled. Some parts have been combined (the bottom cover and the elastic guide pin). I also made all the hardware visible in this photo (minus some screws and the three pieces of elastic).

There isn’t too much to say about this one. It’s exactly what the title says. Cage main and wheels to support the T-Motor F80 Pro. I’m using the 1900KV version.

Because of how close the wire on the motors got to the flywheels, I changed the wire channels in the cage main from just a ditch to a ditch with a cover over it. Makes it a little tricky to snake the wires through, but not too bad.

I used the mag release with the circular surface, which seems to work fine with Rapidmag heavys. Both mags I printed had to be corrected, one with a file, one with a design change prior to printing. The protrusions on the back made them a very tight fit in the magwell. I also remixed the design on the second the one pictured to have press-fit and then bolted in connectors between the top and bottom halves of the extended version, rather than using a glued on connector band. I used some dovetail shapes to keep the magazine walls aligned, although I didn’t think of this until after printing the left half of the mag so they’re only tested on the right. I also have a modified two-part pulley that is way easier to install. I have not tested this magazine in actual combat yet, so be warned if you want to use it.

Obviously most of the design credit goes to torukmakto4. A little to Matthew Bregg for the motor key geometry from the Orb Weaver, but I changed the wheel socket diameter because at least with my motors, the dimensions provided led to an extemely loose fit and defeated the purpose of rotor-centric flywheels.

Filaments are Yoyi transparent violet and eSun orange and white.

Files are located in: https://drive.google.com/drive/folders/1EQhvMJ-8hj9UgvaTXRw17c0H4IIL82_5?usp=sharing

I’ll also use this time to talk about a few other mods I made to the T19 parts that aren’t specific to this MEGA version. The bottom of the vanilla trigger guard has a sharp corner that dug into my finger so I made a smoother version. I added a hole for a second screw between the stock base and the PVC pipe since the stock wobbles very slightly on my other T19. I knurled the velocity knob since the plain one was very slippery. Those files are in: https://drive.google.com/drive/folders/1URIyVyNpN6N3pW77f1rwl_D3kC0oI2EE?usp=sharing

In the past few months in selling my Aeon Pro Pump Upgrade Kit on Etsy, I had a few issues early on with the strength of the pumpgrip, which had a lot to do with the print orientation I chose. In order to reduce the 'Print-Zip' effect created from two 3d printed parts printed at the same orientation and sliding against each other perpendicular to that, that a lot of our community DESPISES, I printed my pump grip in a weaker orientation which caused some breaks from my buyers. Getting tired of printing replacement parts for my gracious customers who chose to take a chance on a new seller, I wanted to alleviate my problem. While I initially just buffed up the print, I just felt like the print orientation as a whole would be an issue under stronger spring loads. It took me some time, but I think I found a really cool solution that could be applied to future builds within our community: 

Pump Upgrade Kit in question (I really should probably make a little writeup for this on here too)

Video of Pump grip Noise Comparisons.

These experiments actually go back three years, to mid 2018. When I was first designing Project 8 I made this big list of design ideas, some of which I tested before ending up with what was basically just a reshelled T19. One of those ideas was a brushless pusher motor to save weight and bulk from the T19 stepper. I built a test platform using a Racerstar 3000kv 2205 motor, of ultracage notoriety. I knew this motor would not be ideal, but figured if I could get it to at least sort of behave, then it would give me confidence to try to find better motors. This test platform didn’t actually drive a bolt, it just spun an oblong disk while I checked if it would stop in time. It was programmed like a rapidstrike with cycle control, i.e. if the switch was not pressed, the motor was powered, and if the switch was, the motor stopped. I used simonK firmware on the ESC with COMP_PWM and MOTOR_BRAKE enabled. Results were not great (it kept overshooting the switch, even with a large braking zone) so I put it aside and put a stepper in Project 8.

Fast forward to fall 2019 and I tried again. This time I went straight to buying a new motor, the QXMotor QM5006 used on Project 12. I also used some different ideas towards motor control. Rather than being full on or full off like a DC motor, I used some timing controls to slow the motor down a little in advance of the switch. 50 milliseconds after the bolt limit switch is released, the software checks the trigger. If the trigger is not down (so we’re not continuing on in full-auto), then the motor’s throttle is cut to the minimum value that still reads more than zero. This slows the motor down just enough that when it hits the switch it can come to a complete stop.

By and large, I consider this bolt drive system a qualified success. “Success” in that:

- It does actually work.

- It is substantially lighter than a stepper.

- It is axially shorter than a stepper, allowing Project 12 to be about 20mm shorter heightwise than a T19 despite very similar construction.

“Qualified” in that:

- There were some nagging issues with getting double shots when I intended single. More on that later.

- It is substantially wider than a stepper. Made worse by the fact that as an outrunner, wires can’t be run right next to the motor like they could a stepper.

- It’s expensive. $25+ for the motor and then another ~$20 for an ESC. Compared to about $12 for a stepper and a few dollars for the DRV8825 driver.

- Needing to fit the ESC somewhere means the total blaster really can’t be *that* much smaller overall.

Going back to the double shot issue, I had two theories why it might be happening. One was that the 50ms timing when the blaster checks for trigger state to decide whether to fire another shot comes earlier than it would on a stepper. And the other related to Project 12 using a tach-based feed instead of the fixed delays on the stepper-driven Project 8, my only comparison blaster. This, combined with the super light flywheel on Project 12 meant there was less time between pulling the trigger for the first shot and the blaster checking trigger state for the second shot. Time which may not have been enough for me to get my finger off the trigger.

To investigate this I built a T19 driven by a QM5006. This would remove the flywheel inertia from the equation. I also tried putting in some delay-based code as well just to get another data point. The result? ¯\_(ツ)_/¯. Honestly, it’s kind of hard to tell the difference between all of these things now. All the different methods blur together a bit, probably exacerbated by this all happening in quarantine when I’m unable to do any real-world testing. I have been to one game recently where I used this T19, modified to enforce a minimum feed delay of 25ms (the smallest delay the scheduling on Project 8 ever gives) which would really only come into play in a follow-up shot, and, well… ¯\_(ツ)_/¯. It’s... fine? I guess? I don’t really have much to say one way or the other.

With that question decidedly not answered, I also tried working on qualifications 2, 3, and 4. SimonK really isn’t meant to drive a motor one revolution at a time, so I bought some L6234 motor driver ICs and set about programming my own motor controller, driving it forward in discrete steps, like a stepper. I wired it up per Figure 1 in L6234 application note AN1088. There was a false start or two with trying to use a six-step commutation scheme where every phase was either full on or full off but that didn’t work very well. I settled on the PWM based scheme described here, using the lookup table provided. This was a partial success. I could make the motor move and had fine control over it, but it didn’t have the torque to reliably strip darts out of a magazine, even when destroked down to 30mm. It’s possible there was some kind of issue with my circuit – I didn’t have exactly the right diodes to match the diagram, so I just used what I had laying around and that may have caused a problem. Measuring the current through a motor phase showed about 2.5A, which is near the max L6234 rating, so I figured even if the diodes were causing a problem, I probably couldn’t get any more out of it anyway.

All of this testing so far was with the QM5006. I also tried a 260kv 2206 gimbal motor with even less success. About the same story with the L6234, although this one wouldn’t move darts out of a magazine at all, where the QM5006 would do it sometimes. I tried the new motor with simonK as well, and it kind of just jerked around instead of spinning. I’m going to assume I did something wrong here as that should have at least moved it, but honestly at this point I was well past the point of caring and abandoned it.

The T19 was put back together with the QM5006, simonK, tach based feeding and minimum 25ms delay. Project 12 has yet to see a field trial, although I plan to put the same minimum 25ms delay code in it before it does. The L6234s and the 2206 gimbal motor have been set aside. At this point I have no further plans for any testing but have uploaded my giant mess of code in a big unorganized lump here if anyone cares to look at it. Most testing was done on the bench, so the code is generally just cycling the bolt one time. The CAD for my various test platforms is also in there, although at least some of them were not correct as printed and I had to take a saw to them to fix them. As an aside, I learned through this that setting the TCCR0B register on the AVR (which I needed to do to get enough PWM channels for the L6234) changes the timing so that millis(), micros(), and delay() are no longer consistent with the real world. Any code that uses these functions must be corrected by factor of whatever the prescaler is set to, in my case 8. For some reason delayMicroseconds() appears to be unaffected.

Filaments for the T19 are esun transparent green, yoyi transparent purple, and some variety of white, don’t remember the brand. All petg.