• Units are essential when describing real things.

• Good engineering practice demands that each number should always be accompanied with a unit.

• This table does not give an exhaustive list of conversion factors, but instead a minimal (but fairly complete) set is given. From the values below any conversion value can be derived. If you are not sure about this, ask the instructor to show you how.

• A simple example of unit conversion is given below,

1. Beware upper/lower case letter in many cases they can change meanings.

2. Try to move prefixes out of the denominator of the units.

4. Use a dot in compound units.

5. Use spaces to divide digits when there are more than 5 figures, commas are avoided because their use is equivalent to decimal points in some cultures.

• In some cases units are non-standard. There are two major variations US units are marked with ‘US’ and Imperial units are marked with ‘IMP’.

1 ft. (feet) = 12 in. (inches) = 0.3048 m (meter)

1 mile = 1760 yards = 5280 ft = 1.609km

1 nautical mile = 6080 ft. = 1852 m = 1.150782 mi

1 acre = 43,560 ft. = 0.4047 hectares

1 rev = 2PI radians = 360 degrees = 400 gradians

1 barrel = 31 IMP gal. = 31.5 US gal.

1 US gal. = 3.785 l = 4 quarts = 8 pints = 16 cups

1 liter (l) = 0.001 m3 = 2.1 pints (pt) = 1.06 quarts (qt) = 0.26 gallons (gal)

1 cup (c) = 0.2365882 l = 8 USoz

1 US oz = 8 US drams = 456.0129 drops = 480 US minim = 1.040842 IMP oz

1 N (newton) = 1 kg•m/s2 = 100,000 dyne

1 dyne = 2.248*10-6 lb. (pound)

1 kg = 9.81 N (on earth surface) = 2.2046 lb

1 oz. = 28.35 g (gram) = 0.2780N

1 imperial ton = 2000 lb = 907.2 kg

1 atm (metric atmos.) =760 mmHg at 0°C=14.223 lb/in2=1.0132*105 N/m2

1 psi = 2.0355 in. Hg at 32F = 2.0416 in. Hg at 62F = 6894.8 Pa

1 h.p. (horsepower) = 745.7 W (watts) = 2.545 BTU/hr. = 550 ft.lb./sec.

1 J (joule) = 1 N•m = 107 ergs = 0.2389 cal.

°F = [(°C*9)/5]+32, °C = Celsius (Centigrade), F = Fahrenheit

0.252 calories = 1 BTU (British Thermal Unit)

-273.2 °C = -459.7 °F = 0 K = 0 R = absolute zero

0 °C = 32 °F = 273.3 K = 491.7 R = Water Freezes

100°C = 212°F = 373.3 K = 671.7 R = Water Boils (1 atm. pressure)

π radians = 3.1416 radians = 180 degrees = 0.5 cycles

1 rpm (revolutions per minute) = 60 RPS (Revolutions per second) = 60Hz

1 fps (foot per second) = 1 ft/sec

1 mph (miles per hour) = 1 mi./hr.

1 cfm (cubic foot per minute) = 1 ft3/min.

1 year = 365 days = 52 weeks = 12 months

R = 1.987 cal/mole K = ideal gas law constant

K = Boltzmann’s constant = 1.3x10-16 erg/K = 1.3x10-23 J/K

h = Planck’s constant = 6.62x10-27 erg-sec = 6.62x10-34 J.sec

Avagadro’s number = 6.02x1023 atoms/atomic weight

electron charge = 1.60x10-19 coul.

electron rest mass = 9.11*10**-31 Kg

proton rest mass = 1.67*10**-27 Kg

speed of light (c) = 3.00x1010 cm/sec

speed of sound in dry air 25 C = 331 m/s

gravitational constant = 6.67*10**-11 Nm**2/Kg**2

permittivity of free space = 8.85*10**-12 farad/m

permeability of free space = 1.26*10**-6 henry/m

mean radius of earth = 6370 Km

mass of earth = 5.98*10**24 Kg

magnetic flux = weber (We) = 10**8 maxwell

magnetic flux density = tesla (T) = 10**4 gauss

magnetic intensity = ampere/m = 0.004*PI oersted

electric flux density = coulomb/m**2

1 flame = 4 foot candles = 43.05564 lux = 43.05564 meter-candles

• The table below will allow conversions between decimal, binary, hexadecimal, and ASCII values. The values shown only go up to 127. ASCII values above this are not commonly used in robust applications.

• A basic list of ‘G’ operation codes is given below. These direct motion of the tool.

G02: Clockwise circular motion

G03: Counterclockwise circular motion

G05: Pause (for operator intervention)

G17: x-y plane for circular interpolation

G18: z-x plane for circular interpolation

G19: y-z plane for circular interpolation

G20: turning cycle or inch data specification

G21: thread cutting cycle or metric data specification

G25: wait for input #1 to go low (Prolight Mill)

G26: wait for input #1 to go high (Prolight Mill)

G28: return to reference point

G29: return from reference point

G31: Stop on input (INROB1 is high) (Prolight Mill)

G33-35: thread cutting functions (Emco Lathe)

G35: wait for input #2 to go low (Prolight Mill)

G36: wait for input #2 to go high (Prolight Mill)

G40: cutter compensation cancel

G41: cutter compensation to the left

G42: cutter compensation to the right

G43: tool length compensation, positive

G44: tool length compensation, negative

G70: set inch based units or finishing cycle

G71: set metric units or stock removal

G72: indicate finishing cycle (EMCO Lathe)

G72: 3D circular interpolation clockwise (Prolight Mill)

G73: turning cycle contour (EMCO Lathe)

G73: 3D circular interpolation counter clockwise (Prolight Mill)

G74: facing cycle contour (Emco Lathe)

G74.1: disable 360 deg arcs (Prolight Mill)

G75: pattern repeating (Emco Lathe)

G75.1: enable 360 degree arcs (Prolight Mill)

G76: deep hole drilling, cut cycle in z-axis

G81-89: fixed cycles specified by machine tool manufacturers

G81: drilling cycle (Prolight Mill)

G82: straight drilling cycle with dwell (Prolight Mill)

G83: drilling cycle (EMCO Lathe)

G83: peck drilling cycle (Prolight Mill)

G84: taping cycle (EMCO Lathe)

G85: reaming cycle (EMCO Lathe)

G85: boring cycle (Prolight mill)

G86: boring with spindle off and dwell cycle (Prolight Mill)

G89: boring cycle with dwell (Prolight Mill)

G90: absolute dimension program

G93: Coordinate system setting

G94: Feed rate in ipm (EMCO Lathe)

G95: Feed rate in ipr (EMCO Lathe)

G96: Surface cutting speed (EMCO Lathe)

G97: Rotational speed rpm (EMCO Lathe)

G98: withdraw the tool to the starting point or feed per minute

G99: withdraw the tool to a safe plane or feed per revolution

G101: Spline interpolation (Prolight Mill)

• M-Codes control machine functions and these include,

M01: optional stop using stop button

M08: turn on accessory #1 (120VAC outlet) (Prolight Mill)

M09: turn off accessory #1 (120VAC outlet) (Prolight Mill)

M10: turn on accessory #2 (120VAC outlet) (Prolight Mill)

M11: turn off accessory #2 (120VAC outlet) (Prolight Mill) or tool change

M20: tailstock back (EMCO Lathe)

M20: Chain to next program (Prolight Mill)

M21: tailstock forward (EMCO Lathe)

M22: Write current position to data file (Prolight Mill)

M25: set output #1 off (Prolight Mill)

M26: set output #1 on (Prolight Mill)

M35: set output #2 off (Prolight Mill)

M36: set output #2 on (Prolight Mill)

M38: put stepper motors on low power standby (Prolight Mill)

M47: restart a program continuously, or a fixed number of times (Prolight Mill)

M71: puff blowing on (EMCO Lathe)

M72: puff blowing off (EMCO Lathe)

M96: compensate for rounded external curves

M97: compensate for sharp external curves

M99: return from subprogram, jump instruction

M101: move x-axis home (Prolight Mill)

M102: move y-axis home (Prolight Mill)

M103: move z-axis home (Prolight Mill)

• Other codes and keywords include,

Annn: an orientation, or second x-axis spline control point

Bnnn: an orientation, or second y-axis spline control point

Cnnn: an orientation, or second z-axis spline control point, or chamfer

Fnnn: a feed value (in ipm or m/s, not ipr), or thread pitch

Innn: x-axis center for circular interpolation, or first x-axis spline control point

Jnnn: y-axis center for circular interpolation, or first y-axis spline control point

Knnn: z-axis center for circular interpolation, or first z-axis spline control point

Lnnn: arc angle, loop counter and program cycle counter

Pnnn: subprogram reference number

Rnnn: a clearance plane for tool movement, or arc radius, or taper value

Qnnn: peck depth for pecking cycle

Snnn: cutting speed (rpm), spindle speed

;: starts a comment (proLight Mill), or end of block (EMCO Lathe)