DragonTrack Mark 1 rc crawler tracked (rc tank) but fast offroad

Significant Updates

• 2025 Aug 14 — New more grip track pads (experimental)

• 2025 Aug 17 — Added product pages for dual motor steering ESC and gearboxes, and more assembly instructions.

• 2025 Aug 21 — Stronger rear sprocket / final drive and instructions for using 2 ESC.

• 2025 Aug 26 — Steering mix settings for twin ESC.

• 2025 Sep 01  — New tracks for soft ground.

• 2025 Sep 03 — Custom ESC

• 2025 Sep 11 — Final version of track

• 2025 Sep 11 — Mark 1 Dragon Track is complete.

DragonTrack Mark I

Tracked vehicle chassis. Off-road performance can exceed 1/10 crawler car depending on terrain. Custom ESC.

Length 60 cm (2 feet), Weight 6 kilograms (13 lbs).

Video Links

Hosted on Dailymotion.

Crawling over double height bricks (3S battery, 550 brushed, TPU pads): 
https://dai.ly/k1AZKdge9UNWxGDvSQ0 

Bashing over double height bricks (3S battery, 550 brushed, TPU pads): https://dai.ly/k5jbch6lYnLA2lDvSpQ 

Bashing through double height bricks, frontal charge (3S battery, 550 brushed, TPU pads): https://dai.ly/k4eD5wv24B0jrCDvSns 

Bricks 3 tall (3S battery, 550 brushed, TPU pads).
https://dai.ly/k2NOpDnu5PFCPRDvSGk 

Random driving in an abandoned quarry (2S battery, 550 brushed, TPU pads). Tree roots suck.  https://dai.ly/kRIi8YW3QOmSKUDvSuu

Driving with the custom-made DragonTrack ESC (prototype)
https://dai.ly/k4Ok0MrG0RHSQxDMakK

Differences with 1/10 crawler car

If you literally only want to climb up mountains, build a crawler car. If you do anything else off-road, consider this.

RC Motor and ESC Notes

Bill of Materials provides for Level 1 specification:  basic, lowest viable power. Assuming you are upgrading or selecting components, the following information is provided.

RC hobby motors have far more power than power tool motors (e.g. drill or lathe) at the expense of lower durability. Drill motors are designed to provide the minimum required power and last for years. An RC motor is designed to make your car faster than your friend's car until Christmas or CNY and they get a new one.

Tracked vehicles require a lot of torque at low RPM in order to turn. The vehicle must be spun sideways against the ground friction, and you may be doing this in heavy terrain at low RPM. So you require monster torque.

Level 1 Spec - Basic Power/Drive Train Spec for Economy Builds (for full BOM see below)

Minimum and cheapest specification required for credible performance.

Level 2 Spec

This spec removed. See addendum for reason.

Level 3 Spec - Most Expensive but Best Results

Sensored brushless motors and the appropriate brushless ESCs.

Sensored is RC-speak for “has encoder” and a similarly equipped ESC will allow fine control at low speeds, similar to a stepper. The ESC also supports a punch (ramp up) setting that allows you to limit how quicky the power increases when the throttle is used.

RC Hobby BLDC motors are identified by a size code <diameter-length> in millimeters e.g. 3665 meaning 36mm diameter, 65mm long. 36xx are a slight upgrade in speed and power over brushed. 42xx have enough torque that you can gear down to 13-1 (or maybe even lower) and increase the speed of the vehicle. Match the T rating of the motor to your battery voltage. The torque comes from the motor size (larger = more) and T rating does not affect it. The target RPM after reduction is approx 300-400 for normal driving at Level 1 specification.

Note that RC 42xx motors have the same mounting holes as 36xx; you may need to print an adapter for the gearbox, as gearboxes that take 5mm shafts are usually sized for 775 cans. Also check the size of the bullet connectors on the motor and ESC match. 1/10 (such as 36x) and 1/8 (such as 42xx) RC motors use different sizes.

2025 Aug 17 - Obviously you require TWO ESC and two motors, and you setup your transmitter to mix the steering and throttle inputs. (Refer to transmitter manual) unless you can find or build a brushless tank ESC.

2025 Aug 17 - Current advice on gearing is 27-1 or 50-1 depending on performance desired. A 1/10 scale RC crawler car (the type that climbs rocks and drives at walking speed) is typically around 40-1 in low gear, and a basher car (the type that does jumps in a field or skateboard park and drives at 40+ km/h) is about 11-1.

2026-Aug-26 if using two ESC try to make sure they have identical behaviour in forward and reverse,.

Bill of Materials

Frame

Drive and Sprockets Assembly (Makes 1 - you need 2) - LEVEL 1 SPECIFICATION

Road Wheel Module (makes 1; you need 8)

Front Idler Wheels - Makes 1; you need 2

Tracks - Makes 1 track; you need 2. You will have spare links.

Body Parts (battery bay, electronic bay, and dragon module)

RC Electronics (Level 1 - minimum specificaiton)

RC Custom ESC (replaces ESC above)

Print Setting & Filament

You want something rigid and weather-proof. PLA is actually fine except for melting in hot cars. My 2 vehicles are both PLA. PETG should work if you increase the perimeters slightly to allow for its greater flexibility. 

X mm means that number of millimetres perimeter in X, Y and Z.

For example if you use 0.4mm nozzle and print at 0.2mm layer height, then <1.6mm> means 4 walls, 8 floors, 8 ceilings. Infill percentage assumes gryoid or anything with equal strength in all directions. Some parts like idler arms have internal holes to force the slicer to put down perimeters to increase the part strength.

TPU track would stretch and fall off. The track is printed horizontally for strength.

Track PADS are TPU and glued to the track. However 95A TPU (Shore A Hardness 95) has about half the grip of tyre rubber which is round 60A-70A. Consider purchasing a sheet of rubber and cutting it into pads. It really makes a difference. (Ask RC car people how absolutely awful TPU 95A printed tyres are).

2025-Sep-11 The new MK 14 track pad is better and will deform under weight if printed hollow.

Addendum

• NOTE 2025-July-27 Print orientation should be obvious except for 2 parts.

  • Drive mounts are printed on their sides, so that the layer line runs lengthwise down the motor mounts, perpendicular to the motor shaft. Otherwise they will break. Supports are required.

  • Road wheels print with the outer and inner surfaces on the top, the parts that screw together on the bottom, and therefore need supports. I did this so that the outside looks clean and the wheel could be split exactly in half for easy colouring. You could redo the wheel to print support-less if you made 1 piece T and the other piece horizontal.

Assembly Instructions

First, refer to the onshape document. 

https://cad.onshape.com/documents/f590d145ffcc3eeb895b158a/w/7e557c29a8add3622343ad37/e/adbc663975bf6bed8d6e8710 

You should be able to zoom, scroll, and export parts to STEP and STL without creating an account. Shortcuts for navigation are Shift+T to make a part transparent, Shift+I to isolate a part, and space to clear selection. Right click for cross-section. 

All parts and hardware are shown in the onshape document, except for symmetrical components for which only 1 side is shown.

01 Frame Assembly

Build the aluminium frame, blind-jointed. The short bars are tapped for M5. I recommend getting them pre-tapped at the factory, it is not that much more expensive. A template is available on printables to drill the holes in the long bars. To blind-joint, screw an M5x10 button head into the tap in the short bar, insert that into the slot of the long bar, and tighten by putting a tool through the drilled hole in the long bar.

02 Drive Unit

Build the final drive mounts, and assemble them with the motors, gears, and sprockets mounted. You must shim the gears and sprockets very exactly to prevent movement that will result in them coming loose and your vehicle losing drive and damaging its gears. The set screw alone is not enough. Because budget gears are all different sizes, you need to determine the shim spacing yourself. 

I REPEAT: YOU MUST SHIM THE GEARS.

Shim the pinion to the gearbox, the driven gear to the inner bearing, and the sprocket wheel to the outer bearing.

To make the shim, scale the shims vertically in your slicer, and try different sizes until the gears are locked in place. For the gears I purchased, the motor pinion needs 5mm. The driven gear needs 3mm, and the sprocket needs 1.6mm. There is a 0.5mm difference on the left and right side of the vehicle because budget gears are like that. I first measured roughly with a caliper, then printed 3 shims for each part e.g. 2.8mm, 3.0mm, 3.2mm and tried them all.

To install the motor to the gearbox, remove the bottom plate of the gearbox taking care to make sure the whole thing does not come apart. Use low profile screws or countersinks.

Addendum 2025-Aug04 

• Place a piece of office paper between the gears before pressing them together to determine the shim size. This is a reasonably reliable way to getting the correct backlash so they are not too tight (which will reduce their life).

2025 Aug 17 - To attach the pinion for the gearbox to the motor, you either use a special pinion pusher or you support the rear of the motor shaft and tap the pinion down with a hammer. You MUST hit vertically or you bend the shaft or break the pinion, and you must support the bottom of the shaft otherwise you knock it downwards out of position. This can sometimes be fixed by hitting it on the other side. Check your motor and gearbox spin after each stage of touching them.

03 Road Wheels

Build 8 road wheel modules noting that they are not symmetrical. Do not over-tighten wheels or they don't rotate. Do not push the spring rest or wheel arm onto the suspension pin too tight, or it won't move. In an ideal world the suspension pin would have cutouts at the ends to prevent over-tightening.

Rear wheel is just far enough forward to not touch the drive sprockets when the suspension is compressed. This needs a gap of about 30-35mm between the drive mount and the suspension block, and might not be the correct distance in the CAD assembly. The front road wheel is just far enough away from the front 2020 bar that the front suspension can operate. This is about 5mm and might not be correct in the CAD. The 2 center wheels should then be placed so all wheels are equally spaced, as they help to stop the track being thrown.

04 Front Idler Wheels

Build the front idlers. Do not over-tighten wheels or they don't rotate. Some parts of these are not symmetrical.

You cannot cut an MGN-12 rail with a normal hacksaw. An angle grinder etc is required (2025-Aug-04 I am told a dremel works). Do not allow the carriage to slide off the rail or the little ball bearings will fall out. The rail comes with a plastic tool to slide the carriage on and off. Note the position of the screw holes when you cut the rail.

05 Tracks

Use at least 2 threaded insert track link per side, so you can repeatedly remove the tracks for maintenance, or remove a link as they stretch and need shortening (and they will stretch). I recommend making the heat set links a different colour for identification. The technique for re-screwing into plastic is to back up the screw while pushing down so you can feel when it clicks into the existing thread.

Glue the track pads on. This is tedious. I did try a multi-material print but could not get them to stick.

Track screws face outwards for ease of access.

2025-Sep-11 The new track pad, identified as the Mark 14, or MK XIV, Track Pad is tested and working. It is printed HOLLOW (no infill) with 2 walls and the idea the pad itself will compress with weight, allowing it to grip better, like how a tyre will deform to grip. It's still not a rubber tyre, but it's much better than it was before, and functions with Shore 95A TPUs. I recommend the original track with original pads for pavement, indoor and garden; the Mark 14 for general purpose everything; and the spiked paddle tracks for mud.

06 Electronic Connections (Purchased ESC)

2025 Aug 17 - To connect the “BYRC” type tank ESCs, you connect the 3 pin connector to the thottle channel of the receiver, and the 1 pin connector to the signal pin of the steering channel.

2005 Aug 21 - A dual motor tank ESC will connect simply as normal and needs no mixing setup.

See picture below if you are using two car ESCs. Brushed and Brushless are the same here.

The ESC are connected to the battery in parallel. This means they get equal voltage, but share the current so get a battery with a high C rating. The black wire from battery splits into two, and one goes to each ESC. The red wire from the battery splits into two, and one goes to each ESC. One of the 3-pin duponts goes from 1 ESC to the receiver as normal. The other 3 pin dupont from the other ESC has the 2 power lines (black and red here) “cut”  (just pull them out of the dupont plug - i put a new 2 wire plug on and taped it off to stop accidental insertion), and only the signal line (white here, but could be yellow on yours) goes to the ESC. This is because the BEC powers the receiver via these 2 lines, and you can't power it twice or it might break. Only the white wire is used for communication so that's all we connect. Now for steering you have 2 choices:

1. You put 1 motor per RC channel and steer with 2 sticks. This is seriously hard to drive. Tanks haven't been like this for many years.

2. You setup a MIX on your transmitter then you can drive it like a car (sort of). Say you want throttle on channel 1 and steering on channel 2. You connect 1 ESC to throttle channel and the other to steering channel on the receiver. You set the transmitter mix that throttle channel the leader and steering is the follower and set it to copy exactly with +100% mix on both. Then you set a second mix with steering channel leader and throttle channel follower, and set -100% on both. (This is tested and works on Flysky FS-i6, documented 2025 Aug 26) - if it's steering weird, it could be because 1 ESC is forward and the other is in reverse, adn they aren't identical forward and reverse. A typical symptom of this is veering to 1 side when moving straight (as if 1 track was slower) but when you reverse direction, the other side slows instead - this might be fixable with setting mixing +/- 100 instead, and swapping polarity of motor wires (it is with Hobbywing 1060s).

3. A tank ESC will work “out of the box”, just plug it in and choose which channels you want on each transmitter control.

Custom ESC Build Instructions (and why we want one)

There is no cover yet for the ESC. I have only just developed it, but will do it soon. I will also produce a PCB (printed circuit board) design so that the wiring loom is removed.

Generally RC ESC are built for cars and have different performance in forward and reverse. This is fine for driving and braking, or reversing slowly, but bad for tank steering. Drone/plane ESCs often can't reverse (propellers only work in 1 direction). Tank ESC tend to be for toy vehicles and basically randomly bad, with inconsistent performance between left and right or forward and backward etc. HengLong make some good ones for their RC tanks but they use lower power motors. You might be able to swipe one from a large RC bulldozer, but I took the decision to build one and it worked out much better. Control and precision is just much better than the BYRC toy tank units I was using.

Install Arduino IDE. Plug in Arduino (you will need to tell it what port it's connected on and the type of Arduino). Load the software and the code. If you connect your Arduino differently from below, you need to change the pin numbers at the start of the code. Upload the code to the Arduino (CMD+U on Mac). The serial monitor, if set to 118500 baud, will communicate with the Arduino and show you what it's doing. 

However if the circuit is completed you must not operate it with the USB connected and without the BEC and battery connected, as otherwise it will try to power the entire circuit from the Arduino's USB instead of the LiPo battery and this can damage the Arduino. You can (and often need to) operate with both the USB and the LiPo.

Now, build the power circuit. This splits the + and - from the battery into 2 lines, and runs 1 to each motor controller (allow for a 3rd split to the BEC for later). Connect the motors to the motor controllers. You may have to reverse the polarity later so don't solder yet. Use the heavier wire for this cicruit, or the wire could melt or catch fire. Note that the motor controllers are connected to the battery in parallel.

Now you need the digital electronics power circuit. The BEC steps down the battery power to the level used by the electronics, so we are using the thinner wires here. If you bought an RC BEC, the output side is the one with the 2 or 3 pin Dupont connector on and the output is 5V. The input side of the BEC connects to the battery. The output side is split 4 ways, to the receiver, arduino, and to each motor controller. These are connected in parallel. For the flysky i6 receiver, it does not matter which of the channels you use for the power input so long as both go into the same channel. The VIN and GND pins are on the top right of a Nano if the reset button is facing you and the USB port is at the bottom.

Now you need to connect the digital signal pins. The diagram has the reset button of the Arduino facing you and the USB port downwards.

Whatever channel your transmitter steers and throttles on, those are your steering and throttle channels so connect the signal pin of those channels to the Arduino pins D4 and D8 respectively. 

Each motor controller now has 4 connections which are L_EN, R_EN, LPWM and RPWM. The enable the motor in the left and right directions, and are the PWM (speed control) for the motor in those same directions. Refer to diagram.

IMPORTANT - TEST FIRST

First of all, DO NOT plug in a LiPo until after you have checked the connections, and tested with a less flammable power source. You can use (8x) AA batteries. This is 12V and is enough to cause the motors to twitch. This will show the circuit is working. If you disconnect 1 motor, there should be enough power to spin the other one weakly.

After this point, it should drive when connected to a LiPo though you may need to swap over the polarity or reverse a channel on the transmitter.

My code permanently energizes the enable pins of the motor controller and this means that the motors are continually energized even the vehicle is stationary. This means it will resist rolling away downhill if you stop on a slope, but it also means that it will consume small amounts of battery even when stationary. I would fit a LiPo voltage alarm. (If you can program, you can see in the code where this bit is, and experiment with disabling it, for example 5 seconds after the throttle is released; this gives you time to spot terrain or rotate sideways to park on a hill before the motors de-energize)

Before Driving

1. Check Track Tension. When the vehicle is lifted up, the track should not drop under the centre road wheels. Also it should not pull the front and rear suspension too much (a little is OK). Place the vehicle on the ground, and then adjust the tensioners, then lift the vehicle to check.
   
   Addendum 2025-Aug04 - Make sure there is some space on either side of the track tensioner. It will need to tighten to take up the slack created when your suspension lifts on a bump. You may have to remove a track link as your tracks stretch with use. The tracks will be tighter than you think if you are not familar with tracked locomotion.  (This is one reason the front idler wheel support arm is made like that).
    

2. Check fasteners. Seriously, they love to loosen even with threadlock. Non-drilled 2020 is not the best at stopping movement. If you are happy with the build, you can drill the bars and that will reduce your maintenance greatly.
    

3. Check gear shims. They will compress with use.

Notes on Driving/Tuning

Pivot turn means the tracks turn in opposite directions. Skid steer means 1 side is slowed or stopped. Use pivot when stationary and skid steer when moving. Try not to stop 1 side completely, it puts sideways stress onto the track.

Generally you can drive around over most things at walking speed or better. If it grips but doesn't climb, add more power. If grip is poor you may need to apply less. Generally I would point at the target and go to full power until it stops working but that's just me.

Certain situations can cause a track to fall off ("throwing a track").

When you steer, the inside track experiences a backwards force and you will see it loosen between the driving sprocket and the rear road wheel (in the forward direction, the track tensioner will prevent this). If a track comes off, this is usually where it happens. If you keep both tracks moving forwards, this "risk" largely disappears. Otherwise, prefer to stop and pivot; a skid steer with one side stationary puts the wrong kind of stress on the track and requires a single motor to do all the work.

Addendum 2025-Aug-04 - Another issue is running over a ditch, which will also cause the track to drop, when combined with steering this can help to throw a track. Half of the issues with retaining the tracks is track tension. The other half is being aware of the terrain and using the correct driving technique. Real tanks are hard to drive, for basically reasons such as this. During World War 2 “halftracks” (tracks in the back, steerable car wheels in the front) were popular as they could be driven by car drivers. After WW2, tank training schools were established and halftracks vanished (also they invented tank steering wheels).

If you have real rubber track pads, the performance is much better than 95A TPU due to better grip. In my tests (trying to tow weights), the vehicle can pull 2x as much with rubber.

Wheel articulation is not as good as I would like, and you might try softer springs in the 2 middle road wheels.

Brushless sensored motors make a HUGE difference to the agility and control of this vehicle.

You might want to build the vehicle 30mm wider. If you were able to assemble this you don't need to be told how to do that.

My lights are original "Knog Plus" cycle/runners lamps. Convenient as they clip to your clothing while you travel to the off-road site, then can be mounted on the vehicle. You can get RC lights and engine sound systems linked to your transmitter.

Addendum

• NOTE 2025-July-27 I forgot to mention that performance may improve if you add 500 grams  (18 oz) of counterweight (to the front of the vehicle. It is a little rear-heavy. 2025-Aug-06 (Go up backwards to see the effect of counterweight; I should add a climbing vertical wall video)
   

• NOTE 2025-Aug-02 today I tried to drive up a children's playground slide. An RC car with rubber wheels did it fine. A dragontrack wtih TPU 95A tracks could not grip the slide. I spent some time gluing rubber to the tracks and it worked. TPU tracks are really really bad. EDIT: With Mark 14 pads, this is now fixed as much as reasonably possible.
   

• 2025-Aug-08 My tester reports that they prefer 50:1 gearboxes for the basic brushed motors. Control is better, and slower driving can help with traction.
   

• 2025-Sep-11 With the new Mark 14 tracks pads and custom ESC, I feel that version 1 of this vehicle is complete. With the mark 14 you wish to increase vehicle weight further to get more grip.

Photo/Video

Vehicle in photo and video is prototype and slightly different from the final files (e.g. look at the road wheels).

2025-Aug-04 Differences with published file and photo: (1) road wheels have different spacing for the scrws; (2) final drive module and gear cover are fatter in prototype, as it can accomodate a larger 2-1 ratio bevel gear. This proved unnecessary and the final version is smaller at the rear giving better ground clearance.

Coming in Mark II

• Universal motor mounts

• high and low gear, switchable via RC

• better articulation

• High payload modification (10+ kg/22 lbs)

• Screw on track pads

• Lighter weight track

• 2025 Sep 01 - A custom ESC has been built but requires miniaturization to fit into the vehicle - this is coming soon. UPDATE: It's done.

Licence

It is CC-BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/) and you do NOT need to contact me if you are doing anything with this so long as you follow the license.

2025-July-29: Clarifying license that I require that you include vectorized CAD files such as STEP, and link back to the canonical document which is this (and may change should anything happen to Printables).

Addendum

• 2025-July-29 The level 2 spec is removed. The ESC Hobbywing Quicrun 0880 Dual Motor Brushed ESC is not recommended. I looked at the ESC spec from the vendor not the factory. My unit arrived today, and it does not differential steer. (Suffice to say it's going back the vendor!) Level 1 and 3 work, I have a unit loaned to a tester that is driving on sensored brushless motors, and the vehicle driving in the videos is level 1.

Updates

• (THIS UPDATE DEPRECATED/OBSOLETE) 2025 Aug 14 New more grippy track pad (in date stamped folder). They are certainly sticker but less durable. I am still printing a full set to properly evaluate. However I went around the woods with this one link (and one regular one) poking them into the ground and trying to slide it. It worked better but I did manage to break one pad off. TPU 95A, 0.8mm perimeters 10% infill to make it soft. (Consider this an experimental update, print the regular track if you want no risk). (UPDATE: The Mark 14 track pad replaces this and is considered “final”).
   

• 2025 Aug 21 I had the sprocket release its grip from the metal shaft. So a new modification. The drive sprocket and final drive are made more robust. Previously there were M3 grub screws (set screws) and a circular hole for the metal D-shaft. There is now a D-shaped hole for the D-shaft, and M4 grub screws. This makes sure it doesn't slip off. (Also it reminds me that the vehicle needs a clutch or motor power limiter, to prevent drive damage if one side gets stuck). You need (4x) M4 square nut DIN 562, and (4x) M4x8 grub screw (set screw).
   

• 2025 Sep 01 - New tracks for soft ground (called SoftGroundTrack). These dig into the ground and grip very well, and when printed in PLA they are strong enough to drive carefully on concrete. Do not bash over bricks in these. If you use threaded inserts on specific track links, you can swap tracks about as quick as swapping tyres on an RC car. NOTE THey have considerably more grip meaning more motor is required to turn and the track suffers higher sideways stress when doing so, this can make it easier to throw a track (have it slip off). Recommend strength 3 or 4 for these tracks due to print orientation.

NOTE 2025-Dec-25 ESC wiring diagram is missing power connections. I will add these the next time I work on the design.

Disclaimer

These things use Lithium Polymer (LiPo) batteries, and is a hobby project, and I am not a professional engineer. Use at own risk, and take all safety precautions. Lithium batteries are flammable, and potentially explosive.