Are these CNC machining resources free to use?

Yes. Every chart, calculator, guide, and glossary is completely free. No account required, no paywall.

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CNC Machining Resources
& Surface Footage Chart

Free cutting speed references, tolerance guides, engineering calculators, and DFM checklists — built by machinists to help you design better parts and get them machined faster.

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Written by machinists with 30+ years of combined experience.

Your Go-To Surface Footage Chart & CNC Reference Library

Setting the right cutting speed starts with a reliable SFM reference. Our Machinability Chart gives you recommended surface footage values for over 25 metals and plastics so you can calculate spindle RPM in seconds. Just find your material, note the surface footage, and plug the number into the formula: RPM = SFM × 3.82 ÷ cutter diameter.

But surface footage is only one piece of the puzzle. This library also includes tap drill charts, thread references, tolerance guides, DFM checklists, and interactive engineering calculators. Every resource is free, with no account required. They are written and reviewed by machinists with 30+ years of combined shop experience.

We built these tools because we got tired of hunting across five different sites for reliable data. Whether you are a mechanical engineer checking a press-fit tolerance, a buyer reviewing a quote, or a machinist dialing in feeds and speeds, you will find what you need below.

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Everything You Need to Know

From material selection to design optimization, our resource library covers what matters most to mechanical engineers and procurement teams.

Reference Charts

Sortable, searchable data tables for hardness, threads, drill sizes, tolerances, and more. Bookmark and use daily.

Guides & References

In-depth guides on anodizing, DFM, tolerances, GD&T, and more. Written by machinists with 30+ years of experience.

Engineering Calculators

Free online calculators for CNC costs, tolerances, press fits, cutting speeds, bend allowances, and more.

Document Generators

Create invoices, packing slips, purchase orders, and inspection reports. Fill in the form, print or save as PDF.

Glossaries

Look up any CNC or quality term. Browse A-Z or search to find plain-language definitions fast.

Material Grade References

Compare aluminum, steel, and titanium grades side by side. Sortable tables, property bars, and selection tips.

Featured Guides

Key Machining Specs at a Glance

The numbers engineers ask about most, all in one place.

±0.001"

Tightest Tolerance

Achievable on 5-axis CNC with precision tooling. Standard is ±0.005".

Ra 0.8

Best Surface Finish

Mirror-like finish. Standard machined finish is Ra 3.2 μm.

3 Days

Fastest Lead Time

Expedited prototypes. Standard production runs ship in 7-10 business days.

30+

Materials Available

Aluminum, steel, stainless, titanium, copper, brass, and engineering plastics.

5-Axis

Max Milling Axes

Complex geometries in a single setup. Reduces cost and improves accuracy.

48"

Max Part Size

Large envelope milling. Contact us for oversized or non-standard dimensions.

1-5,000+

Order Quantity

Single prototypes to mid-volume production. No minimums required.

100%

CMM Inspected

Every critical dimension verified. Full inspection reports included.

How to Use a Surface Footage Chart

A step-by-step guide for machinists and engineers

A surface footage chart lists recommended cutting speeds in surface feet per minute (SFM) for different material and tooling combinations. The values represent the speed at which the cutting edge should travel across the workpiece surface for optimal tool life and finish quality.

Step 1 — Find your material

Look up the workpiece material in the chart. For example, 6061 aluminum typically has an SFM range of 600–1,000 for carbide tooling, while 304 stainless steel is closer to 200–400 SFM.

Step 2 — Note the SFM value

Choose a value within the recommended range. Start at the lower end for roughing cuts or harder alloys. Use the higher end for finishing passes or free-machining grades.

Step 3 — Calculate RPM

Use this formula: RPM = SFM × 3.82 ÷ tool diameter (inches). For a 0.5″ end mill in 6061 aluminum at 800 SFM, that gives you 800 × 3.82 ÷ 0.5 = 6,112 RPM.

Step 4 — Set feed rate

Multiply RPM by chip load per tooth and number of flutes: Feed = RPM × chip load × flutes. Our Feeds & Speeds Calculator does this math for you automatically.

Running at the correct surface footage matters more than most operators realize. Too slow and you get built-up edge, poor finish, and wasted cycle time. Too fast and you burn through inserts, generate excessive heat, and risk tool breakage. A good SFM reference takes the guesswork out of the equation.

Ready to look up your material? Open our interactive surface footage chart — it covers 25+ metals and plastics with SFM ranges for HSS and carbide tooling.

Common Questions

Frequently Asked Questions

What is a surface footage chart, and how do I use one?

A surface footage chart (also called a surface speed or SFM chart) lists the recommended cutting speeds for different materials and tool types. You use it to calculate the correct RPM for your spindle based on the cutter diameter and the material you are machining. Our Machinability Chart includes surface footage data for 25+ metals and plastics.

Are these resources free to use?

Yes. Every chart, calculator, guide, and glossary on this page is completely free. No account required, no paywall. We built them because we got tired of hunting for reliable machining data ourselves and wanted to put it all in one place.

How often are the reference charts updated?

We review and update our charts quarterly. When new alloy grades enter common use or industry standards change (like ISO tolerance updates), we add the data within a few weeks. If you spot something that looks off, let us know and we will fix it fast.

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