Shop math and reference that just works.
Free calculators and reference data for machinists — no login, works offline, mobile friendly.
Calculators
Thread Calculator
UN/UNJ, metric M/MJ, NPT, ACME, STI — limits, wire measurement, tap drills.
LiveSpeeds & Feeds
RPM, chip load, chip thinning, ball nose, MRR — with starting-point data by material.
LiveTap Drill
Cut & roll form tap drills at any % thread, nearest standard drill.
LiveShop Trig
Bolt circles, sine bar, tapers, dovetails over pins, chords & arcs.
LiveSurface Finish
Feed vs. nose radius, Ra/Rz/RMS conversion, scallop height.
LiveGD&T Position
True position from deviations, bonus tolerance at MMC.
LiveLimits & Fits
ISO 286 shaft/hole fits computed from formulas — H7/g6 and friends.
LiveBar Economics
Parts per bar, material cost per part, scrap percentage.
LiveReference
Drill Size Chart
Wire, letter, fractional & metric — searchable, sortable, with mm equivalents.
LiveMaterial Library
Machinability, properties, and starting cutting data for common shop materials.
LiveInsert Decoder
Type any insert designation (CNMG 432 / DCGT 11T302) — get the full breakdown.
PlannedHardness Converter
HRC ↔ HB ↔ HV ↔ approximate tensile.
PlannedGuides
Tap Drill Size & Percent of Thread
What the chart on the wall is assuming, and when to drill bigger on purpose.
Cut vs. Roll Form Taps
Cutting or displacing — when each wins, and why the drill size changes.
Work Hardening in 304 & 316
Why rubbing is the cardinal sin in austenitic stainless. Feed is your friend.
Why 12L14 Machines So Well
The screw-machine benchmark, what makes it cut, and where it doesn't belong.
6061 vs. 7075
When the cheap one is plenty and when the strong one earns its price.
Machinability Ratings Explained
What B1112 = 100% means, and the four ways the single number lies.
Radial Chip Thinning
Why light stepovers rub instead of cut, and how to feed to fix it.
Choosing Insert Nose Radius
Finish against edge strength, and the feed rule that ties them together.
Reading Insert Designations
CNMG 432, letter by letter, in ANSI and ISO.
Troubleshooting Chatter
A diagnostic order that starts with stickout, not with the speed knob.
Drill Point Geometry
118 vs. 135, why split points exist, and the spot drill angle rule.
Oversize, Taper & Burrs
Drilled hole problems by symptom, from lip mismatch to exit burrs.
Coolant Selection Basics
Flood, mist, air, or dry — matching the fluid to the job.
Measuring Threads with Wires
The three wire method start to finish, without the algebra.
Understanding H7/g6 Callouts
What a fit callout encodes and what to do with it at the machine.
Swiss Guide Bushing Basics
Bar quality, clearance feel, and what diameter wander is telling you.
Collet Types: 5C, 16C, TF20
What fits what, and why dead length matters on a subspindle.