Cricket Bowling Machine with Adjustable Speed and Swing

A cricket bowling machine with adjustable speed and swing fires cricket balls at a batsman using two spinning rubber wheels on an adjustable frame. The machine uses twin counter-rotating wheels driven by 24 V DC motors: a ball dropped through the top hopper is squeezed between the wheels and launched at the panel-set speed. Amateur cricketers rarely get a steady, repeatable feed of deliveries: human throw-downs vary in pace and line, while commercial machines are expensive and need trained operators. A student-scale machine closes that gap — it gives nets a repeatable practice tool built from common motors, steel angle and rubber wheels at a fraction of commercial cost. Swing comes from a speed difference between the two wheels: the faster wheel drags one side of the ball harder, rolling spin onto it, and the spinning seam separates airflow asymmetrically — the Magnus effect, the same physics that bends a swing bowler's delivery.

The Cricket Bowling Machine turns two spinning wheels into a repeatable bowling action. The operator selects a delivery speed on the control-panel knob, and the PWM controller drives both DC motors to the corresponding wheel RPM, shown live on the digital display. A cricket ball dropped into the top hopper rolls down the feed chute and lands in the gap between the two counter-rotating wheels, spaced slightly narrower than the ball so the rubber grips and compresses it on contact. Friction accelerates the ball in a fraction of a second, and it exits the delivery tube toward the batsman at the target speed. For swing, differential mode spins one wheel slightly faster: the faster surface drags one side of the ball, rolling spin onto it, and the spinning seam separates airflow asymmetrically to curve the flight — the Magnus effect. The operator then shifts line and length by tilting or swiveling the head mount and feeds the next ball.

1. The operator sets the delivery speed on the control-panel knob; the PWM controller drives both DC motors to the matching wheel RPM shown on the display.
2. A cricket ball is placed in the top hopper and rolls down the feed chute into the pinch point between the two counter-rotating wheels.
3. The wheel gap — set 10–15 mm narrower than the ball diameter (see builder note below) — lets the rubber grip and compress the ball momentarily.
4. Friction accelerates the ball through the contact zone and launches it down the delivery tube toward the batsman.
5. For swing, differential mode runs one wheel slightly faster, spinning the ball so its seam curves the flight through the air.
6. Line and length are adjusted by tilting or swiveling the head mount, and the next ball is fed for the following delivery.
   Builder note from the build process: set the wheel gap 10–15 mm narrower than the ball diameter. Test it with the power off by pressing a ball through by hand — it should need a firm push without jamming. Too tight stalls the motors; too loose and the ball slips through with low speed.

Tech stack:

• 24 V DC motors (775-class) × 2
• PWM motor speed controller
• Mild-steel angle frame (bolted)
• Rubber throwing wheels (approximately 250 mm)
• Digital RPM display (tachometer)
• Sheet-metal ball hopper and feed chute
• Emergency-stop switch and wheel guards
• 24 V SMPS power supply (230 V AC mains)

The Cricket Bowling Machine combines four capabilities for the practice net. Adjustable speed control lets the operator dial the delivery pace from gentle throw-downs to brisk seam-up pace through a panel knob driving both DC motors with PWM control, so beginners and experienced batsmen share one machine. Swing generation runs the two wheels at slightly different speeds, rolling spin onto the ball so the seam position curves its flight through the air — genuine swing aerodynamics rather than a straight throw. Repeatable delivery mechanics mean every ball leaves the wheels from the same point with the same energy once set: the hopper feeds ball after ball while the rigid steel frame holds wheel alignment, making practice sessions measurable. Finally, the adjustable head mount changes tilt and swivel, shifting line and length without dragging the whole machine around. An RPM display, the gravity-feed hopper and safety guarding support these four in the base build.

• [Adjustable speed control] A panel knob drives a PWM motor controller that sets both DC motors together, with wheel speed adjustable from approximately 800 to 3000 RPM (design target) — slow throw-downs to brisk pace from one machine.
• [Swing generation] A differential-speed mode runs the two wheels at slightly different rates, rolling spin onto the ball so the seam curves its flight through the air via the Magnus effect.
• [Adjustable head angle] The machine head tilts and swivels on its mount, changing the delivery's line and length without moving the frame.
• [Top-feed ball hopper] A sheet-metal hopper holds several balls and gravity-feeds them one at a time down the chute into the wheel gap.
• [RPM display] A digital tachometer on the control panel shows live wheel RPM so the operator can repeat exact speed settings between sessions.
• [Steel frame chassis] A rigid mild-steel angle frame holds the motors, wheels and head mount in alignment under the vibration of spinning wheels.
• [Safety guarding] Wheel guards cover the spinning wheels and a panel-mounted emergency-stop switch cuts motor power instantly.
  Implemented in the base build: all seven features above. Optional customizations (quoted separately): battery-pack operation, automatic ball magazine, remote speed control. Future scope: radar speed readout, spin-axis camera analysis.

• Fabricated cricket bowling machine prototype (wheels, frame, hopper, control panel with RPM display)
• Wired motor speed controller, emergency-stop switch and wheel guards
• Build documentation: component list, wiring diagram, fabrication drawings
• Operating and calibration manual (wheel-gap setting procedure, speed calibration steps)
• Project report PDF (design rationale, fabrication process, testing observations)
• PPT presentation for final review
• Viva Q&A preparation document