Feedwright CNC Calculator

Feedwright is a CNC calculator and machinist calculator for the mill and the lathe: speeds and feeds, RPM, feed rate, chip load, tap RPM and tapping feed, threads, tap drills, bolt circles, tapers and sine bar stacks, in inch and metric. Made for machinists, CNC programmers and operators, toolmakers and students.

It works like a hardware calculator: a steel-blue chassis, real keys and a clear LCD, with each answer labelled so you know what you are reading. Results are shown in decimals, the way machinists read them.

SPEEDS AND FEEDS
• Spindle RPM for milling, turning and drilling, from surface speed and diameter in SFM or m/min
• Surface speed or diameter back from the other two
• Feed rate in IPM or mm/min = RPM × chip load × number of teeth
• Lathe feed rate: feed per revolution in IPR or mm/rev, and feed from a feed per revolution
• Chip load per tooth from feed, RPM and teeth

TAPPING
• Tap RPM from the surface speed and the tap's major diameter, in SFM or m/min
• Tapping feed = RPM × pitch, in IPM or mm/min, worked from the whole RPM you set so spindle and feed stay in step for rigid tapping
• Example: a 1/4-20 tap at 30 SFM runs at 458 RPM and feeds 22.9 in/min (30 SFM is only an example: use the surface speed from your tap maker's chart)

THREADS AND TAP DRILLS
• Unified inch and ISO metric 60 degree threads
• Major, pitch and minor diameters and thread height
• Tap drill for 75 percent thread, or any percent you set
• Percent thread of a given drill
• Built-in tables of common unified and metric threads

BOLT CIRCLES
• X and Y of every hole from the centre, for any hole count
• Start angle for the first hole
• Chord distance between holes

TAPERS AND SINE BAR
• Included angle and compound setting from two diameters and a length
• Taper per foot and taper ratio
• The other diameter from a known angle
• Sine bar gauge block stack for an angle, or the angle for a stack, on a 5 in, 100 mm or any bar

MATERIALS
• Starting surface speeds for high-speed steel and carbide in aluminium, mild steel, 4140, 304 stainless, cast iron, brass and titanium
• Brinell hardness from the indentation diameter, with a tensile strength estimate for steels

WORKS THE WAY YOU DO
• Inch and metric, and each thread keeps its own system
• A results strip shows every solved value at once
• 10 memories, a tape of your calculations, reference tables and a key guide
• Large keys you can hit with gloves on

TRY PRO FREE FOR 7 DAYS
Try every feature free for 7 days, then keep Pro with a yearly subscription. Cancel anytime in Google Play. No ads, works offline.

PRIVATE BY DESIGN
Works offline, no account, no data collected. Everything stays on your device.

How it's calculated: the formulas and tables behind every result, at https://wrightcalc.app/feedwright/

Questions or feedback: support@wrightcalc.app

Results are computed from the formulas shown for each function and are provided for reference only. Material speeds are starting values: adjust for your machine, tooling, setup and coolant, and follow the tool maker's data. Verify every dimension before machining. The developer accepts no liability for loss or damage arising from use.