Robot Car with Claw 

1  Overview

A compact four-wheel platform powered by two TT all-metal 6 V gear-motors (1 : 90). Front and rear axles on each side are locked together by identical Fischertechnik® blue chain loops that run on self-printed 20-tooth sprockets, giving skid-steer handling and excellent traction. Wheels are classic 3″ Meccano pulleys (19b) with Tyres 142b.

Control comes from a low-cost 6-channel 2.4 GHz radio set (eBay item 256822363761); power is a simple 3 × AA pack.

A fluorescent-green C888 narrow geared spacer strip forms a two-finger claw, driven through a standard Meccano worm gear (32) for slow, powerful gripping. All adapters—motor cradles, sprockets, chain guides and pulley hubs—are my own STL files, free to download.

2  Chassis & Drive

• Side rails – two blue 11-hole plastic girders (Meccano).
  
  

• Cross-members – one red Märklin 3 × 5-hole girder (torsion brace) and one green Märklin 11-hole strip (upper-deck tie-bar).
  
  

• Axles – two 5 ½″ blue rods; each wheel clamps to the rod via a printed hub (no brass bushes needed).
  
  

• Wheels – 4 × 3″ pulleys (19b) with Tyres 142b.
  
  

• Chain loops – ≈ 80 Fischertechnik links per side, driving printed 20-tooth sprockets drilled on the 12.7 mm Meccano grid.

3  Claw Assembly

• Backbone – C888 fluorescent-green spacer strip.
  
  

• Fingers – two 3-hole green strips hinged at the tip for a symmetrical pinch grip.
  
  

• Actuation – a Meccano worm gear (32) turns a printed 30-tooth sector fixed to the C888, giving ±45° motion (≈ 55 mm span). At present the worm is hand-cranked; the mount accepts a micro-servo for future automation.

4  Electronics & Power

• Motors – 2 × TT 6 V metal-gear, 1 : 90, seated in printed cradles.
  
  

• Radio – 6-channel 2.4 GHz TX/RX (PWM outputs; no separate H-bridge required).
  
  

• Battery – 3 × AA holder (NiMH or alkaline) centred low between the rails.