Copper Wire Ampacity (Chassis Wiring, 60°C–90°C Insulation)
Units: AWG, Amps (approx.)
| AWG | Amps (approx) |
|---|---|
| 18 | 10 |
| 16 | 13 |
| 14 | 18 |
| 12 | 25 |
| 10 | 40 |
| 8 | 55 |
| 6 | 75 |
| 4 | 95 |
Values are rule-of-thumb for automotive chassis wiring with typical insulation. For continuous loads, use 80% of rating. For long runs, consider voltage drop.
Minimum Inside Bend Radius (Air Bend – Starting Points)
Units: Thickness (in), Min Inside Radius (in)
| Material | Thickness (in) | Min Inside Radius (in) |
|---|---|---|
| Mild Steel | 0.060 | 0.060 |
| Mild Steel | 0.120 | 0.120 |
| Aluminum 5052 | 0.063 | 0.050 |
| Aluminum 6061-T6 | 0.063 | 0.094 |
| Stainless 304 | 0.060 | 0.090 |
Tighter bends may crack or distort, especially for 6061-T6 and stainless. Use proper tooling; consider anneal or larger radius for cosmetic parts.
Sheet Metal Thickness (Gauge vs Thickness)
Units: Gauge, inches, millimeters
| Gauge | Steel (in) | Steel (mm) | Aluminum (in) | Aluminum (mm) |
|---|---|---|---|---|
| 20 | 0.036 | 0.91 | 0.032 | 0.81 |
| 18 | 0.048 | 1.22 | 0.040 | 1.02 |
| 16 | 0.060 | 1.52 | 0.050 | 1.27 |
| 14 | 0.075 | 1.90 | 0.064 | 1.63 |
| 12 | 0.105 | 2.67 | 0.081 | 2.06 |
| 10 | 0.135 | 3.43 | 0.102 | 2.59 |
Gauges are nominal; thickness varies by spec (CRS vs galvanized). Always measure for precision work.
Spark Plug Condition Diagnosis Chart
Use this chart to interpret spark plug conditions. A light tan or gray plug usually indicates optimal combustion. Dark, wet, or oily plugs suggest issues such as rich mixture, oil control problems, or misfire. White or blistered plugs may indicate overheating, pre-ignition, or a lean mixture. Always compare against plugs from multiple cylinders and consider engine load and fuel type.
Tap Drill Size Chart (UNC / UNF / Metric)
Units: Thread Size, Pitch, Major Dia, Drill Size, Decimal (in/mm)
| Thread | Pitch | Major Dia (in/mm) | Drill Size | Drill Dia (in/mm) | Series |
|---|---|---|---|---|---|
| #4-40 UNC | 40 TPI | 0.1120 / 2.84 | #43 | 0.0890 / 2.26 | UNC |
| #6-32 UNC | 32 TPI | 0.1380 / 3.51 | #36 | 0.1065 / 2.71 | UNC |
| #8-32 UNC | 32 TPI | 0.1640 / 4.17 | #29 | 0.1360 / 3.45 | UNC |
| #10-24 UNC | 24 TPI | 0.1900 / 4.83 | #25 | 0.1495 / 3.80 | UNC |
| #10-32 UNF | 32 TPI | 0.1900 / 4.83 | #21 | 0.1590 / 4.04 | UNF |
| 1/4-20 UNC | 20 TPI | 0.2500 / 6.35 | #7 | 0.2010 / 5.11 | UNC |
| 1/4-28 UNF | 28 TPI | 0.2500 / 6.35 | #3 | 0.2130 / 5.41 | UNF |
| 5/16-18 UNC | 18 TPI | 0.3125 / 7.94 | F | 0.2570 / 6.53 | UNC |
| 5/16-24 UNF | 24 TPI | 0.3125 / 7.94 | I | 0.2720 / 6.91 | UNF |
| 3/8-16 UNC | 16 TPI | 0.3750 / 9.53 | 5/16 | 0.3125 / 7.94 | UNC |
| 3/8-24 UNF | 24 TPI | 0.3750 / 9.53 | Q | 0.3320 / 8.43 | UNF |
| 1/2-13 UNC | 13 TPI | 0.5000 / 12.70 | 27/64 | 0.4219 / 10.72 | UNC |
| 1/2-20 UNF | 20 TPI | 0.5000 / 12.70 | 29/64 | 0.4531 / 11.51 | UNF |
| M3 x 0.5 | 0.50 mm | — / 3.00 | 2.5 mm | 0.0984 / 2.50 | Metric Coarse |
| M4 x 0.7 | 0.70 mm | — / 4.00 | 3.3 mm | 0.1299 / 3.30 | Metric Coarse |
| M5 x 0.8 | 0.80 mm | — / 5.00 | 4.2 mm | 0.1654 / 4.20 | Metric Coarse |
| M6 x 1.0 | 1.00 mm | — / 6.00 | 5.0 mm | 0.1969 / 5.00 | Metric Coarse |
| M8 x 1.25 | 1.25 mm | — / 8.00 | 6.8 mm | 0.2677 / 6.80 | Metric Coarse |
| M10 x 1.5 | 1.50 mm | — / 10.00 | 8.5 mm | 0.3346 / 8.50 | Metric Coarse |
| M12 x 1.75 | 1.75 mm | — / 12.00 | 10.2 mm | 0.4016 / 10.20 | Metric Coarse |
| M8 x 1.0 | 1.00 mm | — / 8.00 | 7.0 mm | 0.2756 / 7.00 | Metric Fine |
| M10 x 1.25 | 1.25 mm | — / 10.00 | 8.8 mm | 0.3465 / 8.80 | Metric Fine |
| M12 x 1.5 | 1.50 mm | — / 12.00 | 10.5 mm | 0.4134 / 10.50 | Metric Fine |
Drill sizes are based on ~75% thread engagement. Softer materials may use smaller drills for higher engagement, while harder materials or critical fits may need slightly larger drills.