Engineering · Interactive Suite

DFM cheat sheets & infographics.

Rigorous, physics-driven calculators, alignment charts, and dimensional lookups compiled from 25+ years on the CNC machine shop floor. Interactively configure parameters below to solve sheet bends, audit surface finishes, scale tolerances, and decode GD&T datum reference frames.

Free downloads

Printable cheat sheets (PDF).

Branded one-page references built from the same verified data as our tools — print them, pin them, keep them in the binder. Each opens with a one-click Download PDF.

Materials

Material Properties PDF ↓

Density, strength, hardness, modulus, CTE & machinability for 26 alloys.

Hardness Conversion PDF ↓

HRC / HRB / Vickers / Brinell per ASTM E140, plus approximate tensile (ASTM A370 / SAE J417).

Fasteners & holes

Tap Drill Chart PDF ↓

UNC / UNF / metric tap drills with major diameter + pitch.

Drill Size Chart PDF ↓

Number, letter, fractional & metric drills by decimal inch.

Clearance, Counterbore & Countersink PDF ↓

Close/normal/loose holes, SHCS counterbores, 82/90/100° countersinks.

Inspection & GD&T

GD&T Symbol Reference PDF ↓

All 14 characteristics — symbol, category, datum, definition.

Surface Finish (Ra) Guide PDF ↓

Ra by process plus Ra / Rz / RMS and µin / µm conversions.

ISO 286 Fits & Tolerances PDF ↓

Preferred hole-basis fits with tolerance bands.

Machining

Speeds, Feeds & Chip Load PDF ↓

Chip load by tool diameter + turning/milling SFM by material.

Bolt Torque Chart PDF ↓

SAE / ISO / stainless assembly torque, dry & lubricated.

Analytical Sheet Bending Mechanics

When a press brake deforms a sheet, the material on the outer bend radius undergoes severe tensile elongation, while the inner radius is compressed. The Neutral Axis is the boundary zone that undergoes zero dimensional change, shifting inward by a factor of K · t.

Live Bend Allowance Calculator

Material Preset

Thickness (t)

Inner Radius (Ri)

Bend Angle (θ°)

Neutral Axis Factor (K-Factor)

Allowance (BA)

0.1254″

Setback (OSSB)

0.1200″

Deduction (BD)

0.1146″

K-Factor Standard Reference Table

Material Class	Air Bend K	Bottoming K
Al 5052-H32	0.33 – 0.38	0.42 – 0.45
Cold-Rolled Steel	0.35 – 0.40	0.45 – 0.47
Stainless Steel 304	0.38 – 0.42	0.47 – 0.50
Soft Copper / Brass	0.30 – 0.35	0.40 – 0.42

Interactive Thread & Drill Chart

Search standard imperial and metric thread sizes to instantly isolate tap drill bits, decimal equivalent dimensions, and close/free clearance holes.

Thread Size	System	Tap Drill	Drill Dec.	Close Fit Clearance	Free Fit Clearance	Ideal Hole Depth
#2-56 UNC	Imperial	#50	0.0700″	3/32″ (0.0938″)	#32 (0.1160″)	0.17″ Max
#4-40 UNC	Imperial	#43	0.0890″	#31 (0.1200″)	#27 (0.1440″)	0.22″ Max
#6-32 UNC	Imperial	#36	0.1065″	#23 (0.1540″)	#13 (0.1850″)	0.28″ Max
#8-32 UNC	Imperial	#29	0.1360″	#15 (0.1800″)	#3 (0.2130″)	0.33″ Max
#10-32 UNF	Imperial	#21	0.1590″	#5 (0.2055″)	B (0.2380″)	0.38″ Max
1/4″-20 UNC	Imperial	#7	0.2010″	17/64″ (0.2656″)	19/64″ (0.2969″)	0.50″ Max
3/8″-16 UNC	Imperial	5/16″	0.3125″	25/64″ (0.3906″)	27/64″ (0.4219″)	0.75″ Max
1/2″-13 UNC	Imperial	27/64″	0.4219″	17/32″ (0.5313″)	39/64″ (0.6094″)	1.00″ Max
M3 × 0.5	Metric	2.5 mm	0.0984″	3.2 mm (0.1260″)	3.6 mm (0.1417″)	6.0 mm
M4 × 0.7	Metric	3.3 mm	0.1299″	4.3 mm (0.1693″)	4.8 mm (0.1890″)	8.0 mm
M5 × 0.8	Metric	4.2 mm	0.1654″	5.3 mm (0.2087″)	5.8 mm (0.2283″)	10.0 mm
M6 × 1.0	Metric	5.0 mm	0.1969″	6.4 mm (0.2520″)	7.0 mm (0.2756″)	12.0 mm
M8 × 1.25	Metric	6.8 mm	0.2677″	8.4 mm (0.3307″)	10.0 mm (0.3937″)	16.0 mm
M10 × 1.5	Metric	8.5 mm	0.3346″	10.5 mm (0.4134″)	12.0 mm (0.4724″)	20.0 mm

▸ DFM Tap Guideline: Internal threads exceeding 2.5 × diameter (depth) do not add structural holding strength, but sharply increase the risk of tap breakage from chip packing. Keep blind holes as shallow as design constraints permit.

Design Standard Guidelines

Shop Floor Best Practices

Grain Alignment Sheet Bends

Always layout bend lines transverse (perpendicular) to the rolling grain of the sheet. Bending parallel to the grain reduces your maximum elongation capacity, resulting in visible stress fractures on the outer radius.

grain direction ➔ bend line perpendicular

Recast White Layer EDM Finish

EDM erosion leaves a highly stressed, microscopic recast layer (White Layer). For critical cyclically loaded parts, specify orbital low-pulse EDM finish passes or electropolishing to strip this brittle zone and prevent fatigue cracking.

spec: orbit pass / chemical acid etch

Laser HAZ Hardness Thermal Edge

Thermal cutting in high-carbon alloy steels induces localized martensitic hardening at the cut edge (Heat Affected Zone). Always specify boundary machining or edge annealing if features require tapping or reaming post-cut.

drill clearance: laser width + 0.040″

Keep exploring

Related tools & references

Bend allowance calculator→

Full K-factor and bend-deduction calculator for sheet layout.

Tap & drill calculator→

Tap drill sizes and thread-engagement lookups.

GD&T symbols reference→

Every feature-control-frame symbol explained.

Surface finishes reference→

Ra ranges by process, in depth.

Tolerance cost ladder→

How tightening a tolerance multiplies machining cost.

Technically reviewed by the True Precision Machining engineering team · Last reviewed June 2026

Standards referenced: ASME Y14.5-2018

Have a part that needs to be made right?

Tell us about your part and we'll quote within 24 hours. Aerospace, medical, and defense work welcome.

Request a Quote Contact Us

Quotes in 24 hours