3d Printed RC Military Truck (WIP)

Hi, I'm Willem Smith,

This is my project creating a fully functional 1/10th scale model of the LMTV (Light-medium tactical vehicle) The model was 100% created by me over the last year+ in Fusion 360 and is almost entirely 3d printed.

This little truck is robust, capable off-road, and good to look at. It also isn't that little. It is pretty big for an RC, coming in at several pounds and over 2 feet (600mm) in length. Despite this, it was entirely printed on an Ender 3.

The truck uses off-the-shelf brass worm gears as a final 30:1 axle reduction, which means I was able to build the rest of the drivetrain fairly light duty. This is fundamentally different from most RC crawlers out there, and it really helps to make the most of the PLA parts. The truck uses standard hobby-grade electronics, mostly from a recycled Traxxas car.

The truck features TPU mudflaps, a fully boxed frame (all 3d printed), telescopic driveshafts, super rigid steering knuckles, a detailed interior, a raisable cab, and of course a rugged four-wheel-drive system.

The truck has come a really long way from the original prototype and is really shaping up to be a proper hobby-grade RC that can perform and take a bit of a bashing. (I let 5-year-old kids drive it for 2 hours, the most stressful moments of my life.)

I've been meaning to make assembly instructions for quite some time. Many people have shown interest in building their own.

Eventually, my plan is to make some of the more difficult parts to make (laser cut windows, metal leaf springs) available for purchase for those who can not make them themselves.

Email me with questions: willemanderssmith@gmail.com

Join the Discord for more information: https://discord.gg/b4YsMaVa

Get the model files: https://discord.gg/b4YsMaVa

Fillament (~3kg)

Print in your desired colors. Paint or spray paint is not recommended

Khaki (military beige) PLA ~$25 https://www.amazon.com/HATCHBOX-Printer-Filament-Dimensional-

Army Green PLA ~$25 https://amolen.com/products/amolen-3d-printer-filament-pla-filament-1-75mm-olive-green-

(backup) https://www.amazon.com/OVERTURE-Filament-Printer-Dimensional-

Black TPU (recommended) ~$25 https://amzn.to/3qSezXH

Hardware

At least 4 250mm lengths of 5mm Aluminum rod

~$15 aluminum https://amzn.to/3a14n9L

1x (4pcs) 5mm axle hubs

~$10 https://amzn.to/3oFp6nF

1pcs 1/8in motor coupler

~$9 (for 6) https://www.amazon.com/Vgoohobby-Coupling-Coupler-Connector-

2 SETS (8pcs) 5mm to 5mm universal joints

~$18https://www.amazon.com/Universal-Coupling-Connector-Rotatable-Accessory/dp/B085BPSFSG/ref=sr_1_3?keywords=5mm+universal+joint&qid=1638747483&sr=8-3

Servo linkage

~$11 (2pcs):https://amzn.to/3aJnyDO

M3 bolts

~$23 https://www.amazon.com/iExcell-Stainless-Socket-Button-Washers/dp/B08L9JL5Q3/ref=sr_1_4?

And ~$7 https://amzn.to/3oNXxJ0

Bearings (2 sets 20pcs)

~$22 https://www.amazon.com/uxcell-MR105

Grease

~$5 https://www.amazon.com/Team-Losi-High-Pressure-Black-Grease/dp/B009PBVYPK/ref=sr_1_4?

Electronics

3s capable brushed ESC (Hobbywing 1060 or better recommended)

~$20 https://amzn.to/37RVYTm

80t brushed motor

~$10 https://store.rc4wd.com/540-Crawler-Brushed-Motor-80T_p_825.html

25kg servo

~$18 https://www.amazon.com/ANNIMOS-Digital-Torque-Waterproof-Control/dp/B07GJ6ZCVY/ref=

Radio transmitter and receiver Must be programmable i.e soft limits on servos. Any other remotes will work, however, you may encounter rubbing at full lock steering

~$47 https://amzn.to/2W2IU8e

3s lipo battery(doesn’t have to be high capacity, around 2500mah is fine)

~$14 https://amzn.to/3oY8hVh

Appropriate connectors ESC is Tamiya plug, the battery is Deans connector.

LIPO Battery charger

~$60 https://amzn.to/3oY8hVh

Tools

Required

Electric drill

Hack saw

hex bits https://amzn.to/3a25yFW

Drill bits 3mm, 5mm, 6mm (7/64, 13/64, 15/64) https://amzn.to/3a25yFW

Super/Hobby glue https://amzn.to/38KeoqZ

Recommended

Flexible extension https://amzn.to/381mrOe

Soldering Iron

https://amzn.to/3nlXK5R

Needle nose pliers https://amzn.to/38yxoZo

Utility knifehttps://amzn.to/3bEfPZV

All parts are printed at 0.2mm layer height with a 0.4mm nozzle.

• Gcode for Ender 3 is included under "sliced model files"
• Almost any printer should be able to print this Gcode. (seriously!)
• If you are new to 3d printing, you might want to learn the ropes, this is not an easy project
• 215x215x200mm build volume required

If you plan to slice your own files (important)

• Parts are optimized for specific print orientation
• Look at my Gcode! Especially for parts listed below!
• You can use larger nozzle sizes (much faster), but no guarantees.

Notable parts

Large, flat parts (bed, roof, hatch)

• Use painters tape on the corners (to prevent warping)
• Level your bed
• use between 8-15% infill to save weight

The cab

• Lack of supports is intentional (I have a stock ender 3 hottend and cooler, it prints fine)
• Make sure your printer is in tip-top shape. You don't want to re-print this part

The Frame rails

• Print these at 50% infil+
• Print frame rail connectors at 100%

Axle housings

• 30-40% infill
• try to avoid "elephants foot"
• definitely use tape to avoid warping. Warped axle housings will not work!

Print this little guide out, bolt lengths will be color-coded.

Steps correspond with diagrams in order

Use the bolt guide to determine m3 bolt lengths from the diagrams

1. Cut 1/8 inch brass coupling in half with a hack saw (you may want a vice) You may want to use a caliper to mark the centerline, however, it doesn't have to be perfect. You should now be left with the part shown in figure 1
2. Insert the set screw into one of the holes and tighten it so it is flush. (not sticking out)
3. Sand the surface of coupling so it becomes a more glue-friendly surface
4. Add a touch of glue and press-fit the small herringbone gear onto the coupling using a vice or clamp

1. Cut off a 34.5mm length of 5mm aluminum rod. Don't worry about drilling the hole yet. Mount the bearing onto the shaft (you may need to spin the aluminum in a drill and sand it to get the bearings to slide on)
2. Mount the large herringbone gear onto the shaft (may require drilling out or heating with a lighter) Align it as shown in figure 3 with around 5mm sticking out the back of the gearbox housing (to the left in the diagram)
3. Drill a hole through the shaft with a 3mm or equivalent drill bit, using the gear as a guide
4. Bolt the gear on with a 14mm m3

1. place the smaller gear in place (meshed with the larger gear)
2. loosen the set screw and slide the motor shaft into the gear coupling
3. tighten set screw onto the D-shaft (as shown in figure 3)
4. Bolt the gearbox cover on with 5 20mm m3 bolts

1. Insert the servo into the mount (it's tricky but you'll get it)
2. bolt it down with 4 4mm m3 bolts

Follow the diagram to bolt together the front and middle left frame rails

Parts in this diagram:

1. front left and middle left frame rail
2. 1x front frame rail gusset
3. 1x rear frame rail gusset
4. 2x leaf spring brackets
5. left motor support
6. left shock tower
7. 6x 20mm m3
8. 2x 16mm m3
9. 2x 14mm m3
10. 4x 12mm m3
11. 4x 4mm m3
12. 5x m3 nuts

Repeat on the other side.

Note: The left rear frame rail gusset gets an extra set of 10mm bolts and nuts compared to the right side

1. electronics tray
2. 4x 10mm m3 bolts

This will definitely be tricky, a flex drive will help you out tremendously!

1. Air tanks/mudguard
2. Air cleaner (black)
3. 2x 16mm m3
4. 2x 14mm m3
5. 2x 20mm m3
6. 2x m3 nuts

1. Fuel tank
2. 2x 18mm m3
3. 2x m3 nuts

1. 1x frame bracket
2. 4x 12mm m3

Place the ESC in the electronics tray

connect the leads of the motor to the leads of the ESC. Polarity doesn't matter

Use double-sided tape, velcro, or glue if you dare

1. Rear right and rear left frame rails
2. Rear frame connector
3. 1x frame bracket
4. Hitch plate
5. 4x leaf spring mounts
6. 4x 20mm m3
7. 10x 14mm m3
8. 6x 12mm m3
9. 4x 10mm m3

Loosen the bolts and attach the rear track bar. It should be able to pivot easily

1. Front bumper
2. Front skid plate
3. 2x 30mm m3
4. 1x 5mm m3
5. 2x tow rings
6. 2x 12mm m3

1. backpack
2. snorkel base (attach with glue)
3. snorkel neck (attach with glue)
4. snorkel (black) (attach with glue)
5. 2x tire rack base
6. 4x 8mm m3
7. tire rack crossbar
8. 2x 10mm m3
9. tire rack brace
10. 2x 10mm m3
11. backpack mudguard
12. tire
13. inner rim
14. outer rim

1. backpack assembly
2. 4x 14mm m3

*if you plan on installing the bed on your truck, skip this step

1. mudflap brackets
2. mudflap hangar
3. 2x TPU mudflaps (will potentially hurt rear approach angle)
4. 4x 6mm m3
5. install on frame
6. 10x 6mm m3

1. lower cab
2. cab leg
3. 18mm m3
4. 4x 30mm TPU filament (glue in)
5. 2x cab step (glue in)

1. Cab
2. Lower cab assembly
3. 6x 6mm m3
4. 6x m3 nuts

1. attach grill backing with glue
2. attach either new or old-style grille with glue

1. right and left fender flares
2. 4x 6mm m3
3. 2x 10mm m3
4. 4x m3 nuts
5. right and left engine bay flaps
6. 6x 5mm m3
7. 4x m3 nuts

1. 2x seat pad
2. 2x seat bracket
3. 6x 5mm m3

Repeat 3 times (total of 3 seats)

1. 3x seat assembly
2. 6x 16mm m3
3. 2x 14mm m3

1. glue a 35mm length of aluminum rod into the steering column
2. press-fit or glue the steering wheel onto the end of the shaft

Requires Window kit (purchased from me. Coming soon)

Or laser cut your own Lexan

1. 2x window 1 (carefully glue into place)
2. 2x window 2 (carefully glue into place)
3. 2x window 3 (carefully glue into place)
4. windshield (slide into place, no need to fix with glue

1. carefully glue down the roof (don't use too much glue. You may want to use hot glue so you can get it apart if need be)
2. install the hatch (do not glue)

1. Mirror frames (from kit) press-fit into holes, do not glue
2. 2x mirrors (glue onto frames with super glue)

1. place the cab on the chassis
2. bolt on with 2x 22mm m3

1. 1x servo linkage attached to the servo (use the hole closer to the center) 1x 10mm m3
2. 1x servo linkage attached to the frame with 1x 16mm m3

Work in progress!

More steps coming this weekend!

Questions? Reach out to me: willemanderssmith@gmail.com