5.1 Motor Sizing

We know that, T= F * r, where:

T= Load Torque r= distance between motor and dial's center = 0.5cm F= force Also, F= μ * m * g, where:

μ= coefficient of friction m= Total mass or load g= acceleration due to gravity We will find mass by volumetric analysis.

Loads in our course project:

1 * Dial(Hollow, made of acrylic sheet)

1 * 16 toothed gear(made of acrylic sheet)

1 * 8 toothed gear(made of acrylic sheet)

2 * shaft(made of aluminum)

(i) Gears

The volumes are calculated using Autodesk Inventor.

V1 = 5.6863cc (16 toothed gear)

V2 = 45.80cc (8 toothed gear)

M2 = (V1 + V2) * 1.18 g/cc(density of acrylic sheet) = 0.0607 kg

(iii) Shaft

(1)shaft

The volumes are calculated using Autodesk Inventor.

Radius(r) = 6mm

Length(l) = 50mm

Volume = pi * l * (r)^2 = 1.2978 cc

Mass = 1.2978 * 2.7(density of aluminum) = 0.0035 kg

Therefore total mass, M = M1(gears) + M2(shaft) = 0.0642 kg

Thus, F = 0.0642 * g = 0.6291 N

Torque = (0.6291 * 0.0168) = 0.1080 kg-cm

Torque = 0.1080 * 1.5(Safety factor) = 0.1620 kg-cm

For this magnitude of torque requirement, we can use stepper motor - 28BYJ48

5.2 Battery sizing

Sl.no	Components	Current	Voltage
1	Stepper motor	40mA	5V
2	Buzzer	10 mA	3V
3	LED's	30*4 mA	3.5V
4	Arduino Mega 2560	100 mA	5V
5	Numeric keypad(4X4)	100 mA	3V

Total required current= 370mA*1.2(safety factor) = 444mA

Required adaptor of size = 5V , 5A.