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RC Megatrakk Scrapjet

Red ACTUALLY goes fastah

At the time of writing, I have already completed this project, so I don’t have pictures of the building process.

I try to make my builds future-proof, but my brain can’t future-proof itself :(

I only have two already finished projects (of which this is one) posted on Medium.
Everything else that will follow will have the whole building process breakdown.

The vision

Trying my hand at converting a Warhammer 40K model into an actual RC vehicle.

The size has to be as close to the original as possible, in order to be able to use this model in a standard game.

The vehicle must:

  • House a small rechargeable battery
  • House a small receiver
  • Steer left and right
  • Go forward and backward
  • Have its speed regulated by the transmitter’s button
  • Look as less altered as possible

Depending on the success and level of satisfaction of this, I will endeavour to make more complex ones.

Bottomline — If I can’t get the most simple vehicle to work, there’s not much of a point in making bigger and more complex ones.

The main functional blocks

A transmitter/receiver combo

The car has to receive commands and I need to be able to command it from a distance.
I need to find a receiver small enough to fit into the car’s body, along with its battery, without being noticeable.
The transmitter is relatively less important, as I’m not planning to go rally on sand dunes with this model.

4 Wheels on 2 axes

I need two separate axes in order to have the car steer as well as accelerate independently.

A motor

Which doesn’t have to be very powerful, as the car won’t weigh much.

Given that I’m willing to give up on power, the motor has to be tiny in order to fit the car with fewer adjustments possible.

A battery

That has to power both the receiver and the motor.

It has to be a rechargeable LiPo, so that I can keep it plugged in, charge it on the go and exploit its small form-factor.

And that shouldn’t really explode, but that’s just an added bonus.

The parts and where to find them

As any other sensible person would do, as soon as I got this wonderful idea cluttering my brain, I decided to hit the internet trying to find other fellow madmen who had already done what I was attempting.

Little did I know that nobody (that I could find at least) had done something similar in the past.
Acknowledging the fact that I either was the smartest Warhammer enthusiast or the biggest idiot with a lot of time and dedication to dump into a worthless project, I ventured on researching RC builds and scavenging for similar models I could re-use instead of re-inventing the wheel.

Here’s what I started from:

To make your life a little bit easier, you’re going to need some sort of power tool to ease the grinding/filing process, otherwise you’re going to be spending a lot of time manually trimming plastic, metal and everything in between.

I suggest something along these lines

The building process

First things first — wait a month or so to get the BangGood car whilst praying all of your universe’s Gods that the size and components match with your expectations, otherwise you will have wasted one month waiting for a useless piece of plastic.

Luckily, I’m your test-subject, so by buying the model linked above you are 100% absolutely certain that it will bring you to the same result as mine.

Yeah, you can thank me later

Now to the fun and scary part — destroying your fresh new ride to scrap only the important parts.

As I don’t have the pictures of the building process, we’ll have to make do with some screenshot art.

Cut off the front and back portion of the car.

You’re going to be left with:

  • The front mechanism to turn the wheels
  • The middle portion, which houses the receiver, the battery and 2 sets of wires: one that goes to the micro motor connected to the front wheels and another one that goes to the rear bigger motor.
  • The back set of wheels, connected to the actual motor.

Snip the wires connected to motor in the back, so that you’re free to play around with it to find the best location for it.

Snip the metal chassis from the back portion of the car until you’re left with just the motor portion and the wheels.
Everything else will be glued in position to the GW car.

Now that your main components are sort of ready, let’s start working on the actual project.
Snip the car chassis from the sprue and glue it together.

With a dremel or a hand-saw, enlarge the bottom front-hole in order to fit the front wheel mechanism and secure it in place with some glue or milliput

This is how it should look like:

On to to the actual motor!

File the bottom of the Grot’s seat until it’s flat and try to dry-fit the motor and gear enclosure in the half-circle that results out of it.

Now drill a small hole in the Grot’s seat to make room for the engine wires.
The idea here is to have the engine glued in the back and get the wires to come straight to the receiver, which is housed in the front.

You’re going to have to desolder the wires from both the receiver and the engine and solder new, longer and sturdier ones.

I’ve used these, but anything along those lines will do:

Once the wires are passing through the hole, you can glue or add our trusty milliput to the mix and secure the engine in place.

The whole engine block from the side — it fits perfectly under the grot’s seat
The engine block from below. The three visible ‘spikes’ are what’s left of the car’s metal structure. This could be further trimmed down.

Last but not least — let’s position correctly the battery and receiver.

As you may have noticed when trying to put it all together, the receiver is a bit fiddly to work with and the wires are a bit stretched.

I have moved the battery around a little bit and whilst doing so my wires connecting to the steering mechanism tore, so make sure to be extra careful with it.

In order to be able to actually turn the car on, you’re going to have to drill a hole in the bottom of the chassis to fit the receiver’s switch.

I’ve drilled mine here, but it all depends on where you can manage to position the receiver:

The hole to house the receiver’s switch

Once you’ve found the position for the receiver and you’ve secured it in place (i’ve used a ton of millput to build a structure for it), don’t forget to solder the wires you passed from the engine hole, otherwise the car won’t move!

The final internal setup should look something like this

Once that’s all done all the mechanical components are in place and the car is ready to be built, primed and painted.

I’ve repurposed some of the parts to fill in some gaps left behind during the process and to also fit the new aesthetic of the wheels and engine.

Here’s some overall shots:

Conclusion and learnings

Mechanical working conversions are actually feasible and they add an amazing spin to an otherwise static hobby.

The tinkering/soldering/mechanical level required is not high (at least for this specific model) and it motivated me to go further with bigger and more complex models.

Whilst there are some rough edges that could have been smoothed out, such as the receiver mount and metal clippings on the chassis surface, I’m happy with the final result and I’m proud to show if off all around.

Curious nerd with a never-ending itch for automation and making things more complex than they should be.