The Ultimate CNC Cheat Sheet — Everything You Need in Seconds (G-Code, Feeds & Speeds, Tools, Fixes and Quick Answers)

This page is designed for speed.

No long explanations.

No theory.

Only the most important CNC knowledge in the fastest possible format.

Use this page when you need instant answers.

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SECTION 1 — MOST USED G-CODES (QUICK LIST)
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G00 Rapid move
G01 Linear cut
G02 CW arc
G03 CCW arc
G17 XY plane
G21 Metric mode
G40 Cancel comp
G41 Left comp
G42 Right comp
G43 Tool length
G54 Work offset
G80 Cancel cycle
G81 Drill
G83 Peck drill
G90 Absolute
G91 Incremental

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SECTION 2 — MOST USED M-CODES
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M03 Spindle on
M05 Spindle off
M06 Tool change
M08 Coolant on
M09 Coolant off
M30 End program

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SECTION 3 — FEEDS & SPEEDS QUICK CHART
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Aluminum

RPM → high
Feed → high

Steel

RPM → medium
Feed → medium

Stainless

RPM → low
Feed → low

Titanium

RPM → very low
Feed → controlled

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SECTION 4 — TOOL SELECTION QUICK GUIDE
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Aluminum → 2 flute
Steel → 4 flute
Finishing → ball nose
Roughing → flat end mill

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SECTION 5 — MOST COMMON CNC FIXES
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Tool breaks

→ reduce feed
→ reduce depth

Chatter

→ reduce RPM
→ shorten tool

Bad finish

→ reduce feed
→ new tool

Wrong size

→ adjust offset

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SECTION 6 — CRASH PREVENTION QUICK CHECK
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Before run

✔ G54 correct
✔ Tool offset correct
✔ Z safe
✔ Simulation

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SECTION 7 — CNC FORMULAS (FAST)
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RPM

RPM = (Cutting Speed × 1000) / (π × Tool Diameter)

Feed

Feed = RPM × Flutes × Chip Load

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SECTION 8 — PROGRAM STRUCTURE (MINIMAL)
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G90 G17 G40 G49 G80
G54
T1 M06
S3000 M03
G00 G43 Z100 H01

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SECTION 9 — FAST DECISION LOGIC
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If tool breaks → reduce feed
If chatter → reduce RPM
If finish bad → reduce feed
If size wrong → adjust offset

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SECTION 10 — REAL CNC RULE
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Shorter tool = more stable

Higher feed + correct chip load = faster machining

Offsets control reality

Most problems come from simple mistakes

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FINAL PRINCIPLE

This page is built to save time.

Use it during programming.

Use it during machining.

Use it when something goes wrong.

Fast answers are better than long explanations when machines are running.