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Machining by the Numbers
Speeds, feeds, power, tool life and cost for planning and quoting machined parts
Calculate cutting data, power, deflection, tool life, cycle time and cost for turned, milled and drilled parts, and turn the numbers into a defensible quote.
Start readingAbout this book
Most machining decisions come down to a handful of numbers: how fast the tool moves across the work, how much material each tooth or revolution removes, how much power that takes, how long the tool lasts and how much the minutes cost. Experienced machinists carry many of these numbers in their heads. Estimators, engineers and buyers often do not, and even experienced people benefit from checking intuition against arithmetic before committing to a quote or a production plan.
This book sets out those calculations in a practical order. It starts with cutting speed and feed for turning, milling, drilling and tapping, then moves to cutting force, power and torque, deflection and chatter, tool life and the economics of choosing a cutting speed. The last two chapters bring everything together into a cycle-time estimate and a quotation.
The eleven chapters follow one fictional example: Harbourline Precision, an invented small job shop, quoting a batch of steel pump flanges. The part, the shop, its machines, its cutting data, its rates and its results are invented for teaching. They are not BIZOMAT projects, clients, prices or claims of performance, and the cutting data are illustrative starting points rather than recommendations.
Calculations use metric units: millimetres, metres per minute, newtons, kilowatts and minutes. Money is in Australian dollars, excluding GST. Always start from your tool supplier’s current data for the specific tool, grade and material, stay within the machine manufacturer’s limits, and follow your workplace’s guarding and safe work procedures. The book is general technical and business education, not a substitute for those sources or for competent supervision.
An independent treatment
The Library already covers machining in a set of overview chapters, including milling cutters and milling strategies and designing parts that are economical to machine. This book is the quantitative companion: it works through the formulas, shows every step of each calculation and connects them to time and cost.
The explanations, the Harbourline case and all worked examples are original BIZOMAT writing. Machinery’s Handbook was consulted to cross-check relationships and models; no tables, figures or text from it are reproduced. Where tool supplier conventions are mentioned, readers should use the supplier’s current published data.
Who this book is for
Machinists moving into programming or estimating, production and manufacturing engineers, workshop owners and technical buyers who need to plan, check or compare the time and cost of machined parts.
What you will learn
- Convert supplier cutting data into spindle speeds, feed rates and machining times for turning, milling, drilling and tapping.
- Estimate cutting force, power and torque, and check them against the machine's capability.
- Recognise when tool or workpiece deflection, rather than the cutting data, limits accuracy and productivity.
- Fit the Taylor tool-life equation to test data and choose a cutting speed that minimises cost or maximises output.
- Build a cycle-time estimate and a quotation that shows how batch size, set-up and tooling affect the price.
Inside this book
Chapters
- 01From drawing to cutting dataThe handful of quantities that govern every machining operation, where trustworthy cutting data comes from, and the pump flange used as a continuous example.
- 02Cutting speed and spindle speedConvert cutting speed into spindle speed for turning, milling and drilling, handle constant surface speed and spindle limits, and calculate facing time and effective diameter.
- 03Turning: feed, depth of cut, removal rate and surface finishChoose feed and depth of cut within the insert's working range, calculate metal removal rate and machining time, and predict the surface finish a feed and nose radius can give.
- 04Milling: feed per tooth, chip thinning and feed rateCalculate milling feed rates from feed per tooth, correct for radial chip thinning and lead angle, and estimate removal rate and time for side milling and face milling.
- 05Drilling, reaming and tapping calculationsCalculate drilling speeds, feeds and hole times including point length, estimate drilling power and torque, choose tap drill sizes and time synchronised tapping cycles.
- 06Cutting force, power and torqueEstimate specific cutting force from chip thickness, calculate cutting force, power and spindle torque, and check planned cuts against a machine's power and torque curve.
- 07Deflection, rigidity and chatterEstimate tool and workpiece deflection with cantilever formulas, see why overhang and diameter dominate, and recognise and reduce chatter before it limits accuracy and output.
- 08Tool life and the Taylor equationDefine tool life, fit Taylor's speed and tool-life relationship to two or more tests, predict life at other speeds and understand why feed is usually a cheaper lever than speed.
- 09Machining economics: choosing a cutting speedBuild a cost-per-part model from machine rate, cutting time, tool changes and tool cost, then find the minimum-cost and maximum-output speeds and see how flat the optimum is.
- 10Estimating cycle timeBuild a cycle-time estimate operation by operation, add non-cutting time and handling, check it against simulation and actual results, and find where the time really goes.
- 11Quoting a machined partTurn cycle time into a quotation: material, machine time, set-up, programming, inspection and tooling, the effect of batch size, risk allowances and a quote the customer can compare.
Apply This in Practice
Use these BIZOMAT tools to try the method from this reading with your own numbers.
Applies this method
Boring Bar Overhang Check (Deflection, Diameter Error, Natural Frequency, Longest Overhang)
Applies the cantilever deflection of this chapter to a boring bar: diameter error, overhang ratio, natural frequency, and the longest overhang and feed for a tolerance.
Used in Deflection, rigidity and chatter
Applies this method
Reaming Plan (Drilled Size, Stock, Speeds, Cycle Time, Holes per Reamer)
Plans a drill-and-ream operation: pilot drill from the reaming allowance, stock per side, speeds, time per hole and reamer use.
Applies this method
Slender Work Turning Check (Work Deflection, Diameter Error, Steady Rest Spacing)
Applies beam deflection to a slender part turned between centres or in a chuck: diameter error, longest unsupported span and steady rests needed.
Used in Deflection, rigidity and chatter
Related Tools and Examples
Useful alongside
Cutting Speed Adjusted from the Feed and Speed Tables (Turning, Milling, Drilling)
Adjusts a tabulated feed and speed pair to your own feed, depth and width of cut before the spindle speed is worked out as this chapter shows.
Related to Cutting speed and spindle speed
Useful alongside
Economic Production Quantity Check (Batch Size, Run Length, Peak Stock, Cost against Current Batch)
Finds the batch size that balances set-up against holding cost, the batch-size effect this chapter shows in a quote.
Related to Quoting a machined part
Useful alongside
Grinding Economic Wheel Life and Wheel Speed
Carries the minimum-cost tool life idea of this chapter over to grinding wheels, from the dressing cost and the time to replace the wheel.
Useful alongside
Grinding Force, Torque and Power from Equivalent Chip Thickness
Applies the specific cutting force method of this chapter to grinding, where the chip is far thinner and the specific force far higher.
Related to Cutting force, power and torque
Useful alongside
Metric Ground Thread Tap Limits (M Profile: Pitch and Major Diameter, D and DU Limit Numbers)
Checks the tap itself against its pitch and major diameter limits, so a worn or wrong-limit tap is found before the go and no-go gauges this chapter uses reject the holes.
Related to Drilling, reaming and tapping calculations
Useful alongside
Milling Mean Chip Thickness and Equivalent Chip Thickness (Feed per Tooth for Light Radial Cuts)
Gives the mean and equivalent chip thickness and the feed per tooth that holds a chosen chip at light radial engagement, the handbook form of the chip thinning correction this chapter applies.
Related to Milling: feed per tooth, chip thinning and feed rate
Useful alongside
Slot Milling against High-Speed End Milling (Feed Rate, Equivalent Tooling Time, Cost per Part)
Turns the raised feed per tooth this chapter allows at light radial engagement, and its warning that slotting is the hardest case, into a cost per part for slotting against high-speed milling.
Related to Milling: feed per tooth, chip thinning and feed rate
Useful alongside
Surface Finish Change with Tool Nose Radius (Colding Rule)
Sets the empirical nose radius rule beside the geometric finish rule this chapter uses, which overstates the gain from a larger radius.
Related to Turning: feed, depth of cut, removal rate and surface finish
Useful alongside
Tool Life from the Force Ratio FH ÷ FC (Colding)
Links the tool life this chapter models with the Taylor equation to the measured force ratio, for tool-change monitoring.
Related to Tool life and the Taylor equation
Useful alongside
Trepanning Plan (Ring Cut Power, Torque, Time and Core against Solid Drilling)
Applies specific cutting force to a trepanned ring and a solid drill, comparing their power, torque and time for a large hole.
Related to Cutting force, power and torque
References and source notes
The manuscript and worked examples are original BIZOMAT writing. References inform particular concepts; their authors do not endorse this book. Web references were consulted on 18 October 2026.
- Erik Oberg, Franklin D. Jones, Holbrook L. Horton and Henry H. Ryffel (Industrial Press). Machinery's Handbook, 29th edition (2012). Consulted to cross-check the cutting speed, metal removal and machining power relationships, the theoretical surface finish relation for turning and the economic tool-life model. No speed and feed tables, figures or text are reproduced; use your tool supplier's current data.
- Frederick W. Taylor, Transactions of the American Society of Mechanical Engineers, vol. 28. On the Art of Cutting Metals (1907). Original source of the tool-life relationship used in Chapter 8.
- W. W. Gilbert (American Society for Metals). Economics of Machining, in Machining: Theory and Practice (1950). Classic derivation of minimum-cost and maximum-production tool life used in Chapter 9.
- International Organization for Standardization. ISO 3685:1993 Tool-life testing with single-point turning tools (1993). Standard method for tool-life testing, referred to when planning the tests in Chapter 8.
- Sandvik Coromant. General turning formulas and definitions (current web guidance). Tool supplier reference for turning speed, removal rate, power and specific cutting force conventions, compared with the derivations in Chapters 2, 3 and 6.
- Sandvik Coromant. Milling formulas and definitions (current web guidance). Tool supplier reference for milling feed, chip thickness and power conventions used in Chapters 4 and 6.
- Sandvik Coromant. Drilling formulas and definitions (current web guidance). Tool supplier reference for drilling feed, power and torque conventions used in Chapter 5.
- Yusuf Altintas (Cambridge University Press). Manufacturing Automation: Metal Cutting Mechanics, Machine Tool Vibrations, and CNC Design, 2nd edition (2012). Background on cutting mechanics and chatter stability for Chapters 6 and 7.
- Richard G. Budynas and J. Keith Nisbett (McGraw-Hill Education). Shigley's Mechanical Engineering Design, 10th edition (2015). Standard cantilever deflection relationship used for the tool deflection examples in Chapter 7.
- Australian Government, business.gov.au. Prepare quotes (current web guidance). Plain-language guidance on quotes and estimates, referred to in Chapter 11.
- Safe Work Australia. Model Code of Practice: Managing risks of plant in the workplace (current web guidance). Australian guidance on machinery risks. Calculations in this book never override guarding, safe work procedures or the machine manufacturer's limits.