Saturday, October 19, 2013

Nitron Build, pusher motor swap!

The NIC has never really had a proper solution for the Nitron. The stock pusher motors just don't rev high enough to be useful with typical pack voltages as used with stock (and any reasonable sort of swap) flywheel motors, and the typical workaround is to use a very high voltage "B battery" for the pusher. This is clunky and inelegant to have 2 batteries on board a single gun, plus the B battery is usually a dirty hack such as alkaline 9-volts.

Furthermore, the OEM pusher motor doesn't handle this abuse too well and there are reliability and heat problems. The one pulled out of this base gun smelled like it was on fire with only free revving on a 12.0V NiCd pack. "Like burnt popcorn", the Nitron Boom'ers say, and they are correct, they have a distinct smell.

So let's look at alternatives.

This was discussed on the HvZ Forums and some measurements of this motor led me to believe it was a 280 - but it is in fact a 260. The black motor at left is a Sagami Cyclone 280, center is the stock 'tron pusher motor, and right is a 130.

Here, have a closer look at the diameters.

Notice that a 280 does not fit the mount, but the 260 is the same diameter as a 130 can, more or less!

A 130 fits quite nicely.


The bearing snout fits the stock pilot diameter perfectly.

The hold-down is easily modded to fit a FC/FA type endbell.

Well, that sure makes it easier! There are TONS of 130 motors available from mild to wild with every Kv under the sun... AND the larger 180 derivative, which of course has the same cross-section but is longer. We are familiar with these beasts from dart-firing flywheel guns and probably have a bunch of some type of 130 laying around gathering dust.

That ought to cover everything you could possibly want to do with a 'tron.

Even a Stryfe motor would be far superior on a 'tron pusher to overvolting the hell out of that 260 and burning it up.

For this build, I used a Rapidstrike motor. The Kv of these plays well with getting around 550RPM out of a 12V pack.

I didn't trust the stock brushes, though. This is a commission.

I dropped in a carbon brush pack, which I pull out of cheap FC130 motors from ebay. More on those later, they are a good durability and possibly performance mod for metal brush 130 motors.


A piece of PVC was glued into the mount to anti-rotate the motor. The stock 260 was held by the terminals! Unfortunately this is typical of Nerf's motor installs.

The rest of the 'tron came together as expected.

This was wired for Rapidstrike-style cycle control of the pusher. Unfortunately, this motor did not have near enough "traction" to brake the gearbox even at low ROF. Perhaps a high-end hot wound 180 and an active-braking MOSFET, and a timing adjustment (which would be easy) could solve that, but I just converted this one to AB only with no cycle control. Firing a single round is possible, but you have to download your mags by one since the pusher may be forward. Far less a problem in the 'tron than in a RS with its pusher design and darts.

Stock flywheel motor, which seems to have decent torque once it gets fed current. I would have experimented more if I could actually use Vortex around here... it's banned from the local HvZ.

Speaking of current...
This is the pack for this thing. I was given an unused 10 cell Sub-C NiCd cordless drill pack by someone who had LiPo'd their drill. This pack was chopped up and reassembled in a 5x2 staggered brick. Cost: Nearly nothing.

The flywheel revs promptly up to full speed (which is impressive given the EXTREMELY THICK RIMMED and HEAVY high-inertia design of the flywheel, designed to compensate for alkaline voltage sag) and the pusher churns angrily away at 550-600RPM. Except, I have exactly 3 rounds of XLR to my name, and zero mags! Testing and possible tweaks to come later.

Nitron Technical Observations

This is probably a Part 1 since this is an ongoing project, but I am working occasionally but steadily on a 'Tron overhaul for an HvZ player at a nearby campus. Along the way I came across 2 odd details about the stock Nitron electrical system.

One is that the pusher is cycle-controlled (with the switch mounted on top of the battery box that follows the stepped edge of the cam disk) but there is no active braking. Weird. Except it makes sense in combination with the next bit, which makes AB difficult to implement in the stock configuration.

This strange heatsinked 4-pin package hanging off the side of the PCB is the first thing many people notice about the stock motor setup on the 'Tron pusher.

Speculation has included that the device is a voltage regulator or a MOSFET (used for solid-state switching of the motor power with the small switches scattered all over the Nitron's guts for various interlock purposes). At least people are aware you have to remove this PCB to do anything useful. As it turns out, "voltage regulator" is a very close guess.

A close inspection of the IC in question reveals the markings "UTC" and "AN6651". A quick Google nails it down what the mystery component is: a linear motor speed control IC. More or less a fancy linear voltage regulator that allows taking into account the motor IR and Kv in the selection of 2 external resistor values to get a very stable constant-speed, governor-like behavior.

Here is the datasheet:

Interesting. Peak current handling is 1.75A. Sounds awful low. Applications listed in the datasheet include tape decks and CD players. So why was this component used to drive the Nitron pusher motor? That is the biggest mystery of them all. Could there possibly be a need for that tight of speed control of this motor? Surely if the stock setup demanded a lower ROF than the direct-driven motor would produce and no colder-wound motor was available, you could do well enough with a dumb, cheap, string of diodes - or even a generic voltage regulator.

Could it have something to do with dropout voltage? Haven't checked, not worth the time to investigate the numbers of this application.

Regardless... the Nitron pusher motor is governed. This is why throwing higher voltage batteries at a stock 'tron makes the flywheel rev higher, but doesn't change the terrible ROF.

Here's a demonstration in which I throw various packs at the stock gearbox without any change in speed. First 7.2V, then 10.8V, then 12.0V.


Friday, October 18, 2013

RapidPistol on video

Got a request for video'ing a Standard Rapidstrike on reddit. Unfortunately, the only one I had was the one in the writeup, which was a commission and just got handed off to another member of the HvZ squad. What I did have, though, was my RapidPistol, which I figured needed a little video demo.

Mag dump (which was an older mag fully loaded to its true capacity of 19 rounds) with streamlines, and then some chrono shots. Sorry I wasn't able to get an outdoor firing test or a target shoot or anything like that, I did this in minutes.

Standard Rapidstrike, an illustrated guide.

This? This is disappointing. Let's fix it.

Saturday, October 12, 2013

Shelf Watch: Nerf suction micro darts, Bonus Rumors!

A short one...

Back in the mid 2012 era, there was a lot of speculation about Hasbro's big shift from N-Strike to N-Strike Elite, and part of that included darts. Some early leaked presentation slides hinted at older types of micro darts being dropped with the introduction of Elite darts.

Well, fast forward to now, and that's just what has happened. Sonics and Streamlines are no more, and New Dart Tag has gone exclusive-distribution in the US and taken the associated Taggers along with. That leaves nothing but them newfangled 1.0g streamlines on the shelves at the vast majority of retailers.

With one exception.

I guess Hasbro felt people would miss the classic Suction Micro. After all, that novelty of having darts stick to targets, walls, doors, glass, even people, is uniquely nerf. So they have soldiered on unchanged, still with orange foam, still in a 16-round bag, with a new Elite-scheme cardboard closure (note the non-elite N-Strike logo).

You knew this? You knew these darts were still in production? Yeah, I expected that. The real reason I posted was that these darts are W-code and have the same old high-density foam that you would expect from W-codes circa 2011. Cool. I haven't polled all of the stores within reach to determine if anything else is out there, but I think it's reasonable to assume all of these are W-code.

Speaking of those blasted tip codes, no one really knows what they come from or mean, only that all darts since about 2007 have them, and the darts are clearly not of the same origins by their minute details. And, sometimes, not so minute details (though Elite standardization efforts that were disclosed to Wired Magazine are definitely a thing, and have leveled the playing field a bit). The best speculation seems to be different plants that Hasbro employs to manufacture darts. I figure that Plant W had their process really down to a science for the old "Non-Elite" Nerf micro foam and thus was the chosen one to keep rolling on these older darts.

Now for those bonus rumors...

Super Soaker Freezefire on!

What have we here?

A quick search turned up nothing but Target site hits. Interesting. Has Hasbro sneaked this one all the way to retail without us noticing?

And what is it? Another triggerless syringe gun. With an ice tank. Meh.

Friday, October 11, 2013

JT Splatmaster Z100 Review, Chrono and Disassembly

Previously I covered the Z90 from a nerf perspective. This is the other pistol in the JT Splatmaster line of spring-powered nerf-like paintball guns, one which probably attracts more interest on first glance from nerfers than the Z90. Why? Well, this.

Wednesday, October 9, 2013

Review: ZombieStrike Elite Dart (30rds/Case)

This is Nerf's matching recolor of the Elite dart for the recently released zombie-themed ZombieStrike product line.

Purchased on October 5, 2013 from the Butler Plaza Target in Gainesville, FL, USA. List price was $9.99, I believe I got these for 9.49 or something.

As is evident from the decal, in the US and Canada these are exclusively distributed by Target along with the rest of the ZS line.

As is expected for Elites, the darts are packed in a rigid plastic blisterpack with 2 form-fitting insert trays. Much superior to bags when it comes to protecting the product on the shelf. Buying a case with crushed foam in it sucks.

The foam on these is printed with a single color design that includes a Nerf logo and the ZS "Z-crosshair" badge. Nerf seems to be all about pretty darts nowadays... at least here it's nothing disagreeable and at no extra cost versus standard Elites.

A 15 round sample was examined and subjected to a 160+ shot chrono session. This serves both as a verification of ballistic performance and consistency in a variety of launcher types, and as an aging and short-term durability test. This was overall passed with flying colors; no "duds" were discovered and no darts ceased to be reusable with optimum performance for any reason during the test (which included high-performance flywheels and a 150fps springer).

Quality control seems to be excellent, with the exception of 3 observed minor foam consistency problems in the 15 round sample; two darts had out of round foams, and one had an undersize foam. Unlike some older K and J code standard Elites, there is little glue spillage around the tip. The tips appear to be installed on-axis and straight and are themselves consistent in their dimensions. This is likely associated with the observed success in using these darts in longer barrels, a common problem area for rubber tipped darts. As a sidenote on use of longer barrels with elites, tight barrel fits must be avoided regardless of spring gun parameters and optimal fit; here the test NF was equipped with a Blue Line CPVC barrel.

The tip code is J-dot. The tip construction appears to be standard. Like other J-code Elites, these tips have a white core and a colored dome. The foam is standard J-code foam (which should be familiar on elites, and is more or less identical to other foams available on elite darts including K-code and W-code) except in green color.

There is one observed difference with these tips from earlier J-code standard (orange/on blue foam) Elite tips, though, and that is the surface finish and level of tack. Early elite tips were notorious for sticking to magazine bodies and feed system parts resulting in jams.

Oops. This malfunction is typical of early Elite Standards from the 2012 era, which all had very tacky tip compounds and overhanging dried contact cement around the tip. This still may be the case with K and J code...
The ZS dart tips, however, are much slicker. Loading an 18-round magazine without any care to setting the rounds back from the front surface did not result in any feed trouble.

Overall, I would rate these highly recommended. In terms of consistency and durability, they are as good as it gets with the Elite type darts, and performance is nominal. While not available in 75-round cases, in 30-round packs they have the same price point as standard elites, yet are a brighter, more visible color (which assists in recovery to keep costs low), better long barrel compatibility, and better reliability in all the popular stock class guns. And they are zombie-themed for the HvZ crowd. What's not to like?