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.


  1. So I can only assume that you did a full rewire on this Nitron. I am currently working on one, but was wondering if you had a wiring diagram handy.

    1. If you have no cycle control, it's just switches feeding motors.

      If you want a cycle-controlled pusher (which does not work out with the RS motor and the stock switch timing) the pusher circuit would be identical to a RS.

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