TR 0

Delta layout: single front steer (fork + headset) and two rear wheels fixed on a single rear axle (driven). This makes 2-WD simpler: drive both rear wheels through a solid rear axle or micro differential/geartrain.

Frame: tubular frame with two side rails that split rearwards to cradle the rear axle. Exposed triangular bracing for industrial look.

Seat: reclined mesh/mesh-moulded seat (thin ribs) — keep cross-sectional thickness minimal for print.

Cockpit: single central steering column with short T-bar. For model fidelity include Ackermann steering tie-rod detail on the front fork if you want realism.

Scale detailing: pedal crank, chainring, chain run/guard, tiny chain tensioner, small rear sprockets or belt pulleys for visual realism.

4 — Drivetrain (2-WD) — practical options

Passive display (no drive): print static axles; show chainrun for realism. Easiest.

Single motor → solid rear axle: use one micro gearmotor (e.g., 6–12 V, 30–100 RPM) driving a small pinion that meshes with a gear on the solid rear axle. Both wheels rotate — simple and robust.

Two micro motors (one per wheel): more complex but independent wheel drive possible. Need micro wiring and mount bosses.

Differential (scale): tiny bevel-gear diff is hard at this scale — prefer solid axle or one motor + gearbox that splits torque to both wheels.

Recommendation for hobby micro motor option (if motorising): use one motor + tiny gearbox + shaft coupling to a rear axle gear. Make a small printed gearbox housing in the center of the rear axle.

5 — Materials & finish (for 3D print prototype)

Prototype (visual): PLA (easy print). Layer height 0.12–0.16 mm for good detail.

Durable parts (axles, pins): steel rods (0.8–1.5 mm diameter depending on scaled bore) or brass/steel pins.

Flexible parts (tires): print tires in TPU (if you want traction); otherwise paint rubberized paint over printed rims.

Glue / fasteners: tiny M1–M1.6 screws, cyanoacrylate for permanent joins, small press-fit pins for axles.

6 — CAD & printing tolerances / modeling tips

Wall thickness: minimum 0.8–1.0 mm for small structural pieces; thin decorative parts can be 0.6 mm but risk fragility.

Snap fits & press fits: for axle bores, design bore diameter ~0.2 mm larger than rod diameter for smooth rotation (scale dependent). Example: if using a 1.0 mm steel rod, bore = 1.2 mm.

Fillets: add small fillets (0.3–0.6 mm) to tube intersections to avoid fragile sharp corners.

Clearance: chain and crank clearances extremely small at this scale — model chain as a thin rail or printed linkless impression rather than true moving chain unless you scale wheels up.

Print orientation:

Long frame rails: print with the rails lying flat to reduce supports.

Wheels: print with the axle hole vertical to get a clean bore.

Seat: print with seat surface up for detail, add minimal supports under the seatback.

Supports: use supports only where necessary (overhangs >60°). Remove support contact with small taps to preserve detail.

7 — Bill of Materials (BOM) — model version

(Quantities for one 1:34 model)

Printed: Frame halves (2), seat (1), front fork (1), front wheel hub + rim (1), rear wheel hubs + rims (2), rear axle housing (1), steering column parts (1), pedals/cranks (pair printed)

Rods/pins: steel rods 0.8–1.2 mm × 50 mm (2–3 pcs) for axles/steer shaft

Fasteners: M1.2 or glue (several)

Tires: TPU printed or painted rims (3)

Optional: micro gearmotor (1), micro gearbox, small battery holder (if motorized)

Paint & finish supplies: primer, acrylic paints, thin brushes, matte varnish

8 — Exploded view & assembly sequence (brief)

Assemble rear axle gear onto rod; mount rear hubs/wheels to axle ends (press-fit or glue).

Join lower frame rails; insert rear axle assembly into frame cradle.

Fit bottom bracket/crank assembly into frame; align chainline.

Fit seat onto frame rails and secure.

Mount front fork & steering column; add tie-rod/steering link.

Attach front wheel.

If motorised, install motor and route drive to rear axle; test rotation and clearances.

9 — Micro-motorization suggestions

Motor: small DC gearmotor (e.g., 6–12 mm diameter gearbox) or micro hobby motor. Aim for low RPM with torque to move the model if desired.

Power: coin cell holder or micro LiPo (very small) for running demo; keep voltage consistent with motor rating.

Control: simple on/off or small ESC; no need for complex electronics for demo.

10 — Aesthetic & surface detail ideas

Add rivet/head bolt bumps along frame for industrial feel.

Exposed chaincase strip (thin wall) for realism.

Slight asymmetry in seat fabric texture or small vents near lower frame.

Option: make a transparent display base (acrylic) with a small name plaque that includes scale and model name.

11 — Deliverables I can produce next (pick any, I’ll lay it out now)

SVG orthographic sketches (top/side/front) sized to the scale for direct CAD tracing.

Step-by-step CAD part list with named dimensions ready for Fusion360/SolidWorks.

STL pack for printing prototype (low-poly) with recommended print orientation.

Exploded assembly diagram and annotated BOM.