Increase ROF

JonnyTwoCombs

I want to increase the ROF on my gun. Other than fitting a high speed motor what else should I be looking at?

At the moment, a decrease in spin up would be my priority.

My AEG is a M4 variant.

Oh! On the subject of motors, would any ‘long’ motor fit? The reason I ask, is because I came across a high speed motor on ehobby and the product description stated it was for a M14 DMR type gun. While another, which appears to be identical is described as for a M4 / M16 type gun.

DeBurca

It would help if you said what your current setup is
Is the gearbox bog standard or has any upgrade work been done on it
What make and type of battery are you using and what make of M4 is it

Decoy

Info on exact make/model of gun would be useful.

What battery are you using? A 9.6v NiMh will give better RoF than 8.4v. A 7.4v LiPo (with sufficient Mah/C-rating) will give better RoF than a 9.6v NiMh. An 11.1v LiPo will give best RoF and will also give the faster trigger response you're looking for but you need to be sure your gearbox is up to the job with quality gears, good shimming & high-end bushings/bearings

You have two options on the motor/gear side of things. High-torque motor coupled with high-speed gears OR high-speed motor coupled with quality standard ratio gears. You really need to talk to a tech to know what the best solution for your gun.

Stercus Accidit

There are short, medium and long type motors as standard, there may be some proprietary motors also but the above are the common ones.

The M4 uses a type 2 gearbox, I cant tell you off the top of my head but I think it is a long motor, and any motor calling itself a long motor will generally work in it.

Many recommend the g&p m120 as a fast reasonably priced motor, I have one and it does seem to work well in my high speed set-up, but it isn't a systema turbo or TM eg1000.

You can also increase the voltage of your battery to 9.6v if you haven't already, higher voltages may require a mosfet(solid state switch) to reduce wear on your trigger contacts from the high voltage arcing occurring when connecting and disconnecting.

Then you have your lightweight gears, bearing bushes, bearing spring guides and so on, a good shimming of the gears is vital for a high rof also.

Higher grade wires also increase efficiency for a particular voltage of battery as does the mosfet.


A mosfet with active breaking would be a good way to reduce spin-up combined with a 9.6v battery and/or g&p m120.

Beez

Just put a G&P m170 motor in my M4 and ROF is insane and trigger response instant.

I would recommend it if your gearbox can handle it.

JonnyTwoCombs

Thanks lads,

Yeah, it’s a type 2 gearbox with a long motor. My confusion surrounded the product description on ehobby – why describe two similar products has having different applications.

The gearbox its self is a stock VFC with silver coloured wiring (silicone I think). I’m already running a 9.6v 2000mah battery in it. But I would like to increase trigger response.

I’m unsure what the exact ROF is at the moment, but it is far from having a mad ROF. I would like to increase this a bit, but having a quicker trigger response would be my priority.

Stercus Accidit

Does it have plastic bushings?

Get some metal or bearings ones so.

Mosfet is a lovely thing to have if you can install it or justify the cost, you get fewer issues with semi-auto if you have active breaking, over spins and all that.

Easiest would be new motor, vfc motors can be quick but have a bit of spin up time if my akms was anything to go by.

JonnyTwoCombs

The bearings, I’ll told are 6mm and metal. I’ve only had the gearbox opened once and the tech told me it was up to the usual VFC high standards.

The only plastic parts were the piston, air nozzle and tappet

Decoy

I found this useful: http://www.youtube.com/watch?v=vXpMxb0JVMc

I would say your easiest option is to try a 7.4v decent-Mah/good C-rating LiPo and see how that goes for you. The 9.6v 2000Mah NiMh you are currently using can provide around 24amps to the motor. That's not bad but most of the numbers I have seen say a good motor needs 25-30amps to run efficiently. A 7.4v 1900Mah 22C LiPo (specs of my Kong Power LiPos) can provide almost 42amps to the motor, far more than is required, so the motor will run better. If you're @ Hellfire on Sunday you can borrow one of my LiPos to test.