Formulas, worked examples and the typical mistakes from the workshop – explained so that you can work it out yourself on your next job. A new article is added every week.
Calculation guides
Engineering formula book for metalwork as an app – over 50 formulas with calculation steps
Over 50 calculations from areas to heat, every formula rearranged and worked out with sketch and calculation steps.
Learn CNC programming – learning path, G-code and cycles to DIN/PAL
Interactive learning path for turning and milling, all G and M codes with example blocks, cycles with input mask.
Calculating ISO fits – understanding H7/g6, H7/p6 and more
Read a fit designation, determine the limits of size and see whether you get clearance or interference.
Tap drill size for threads – formula and chart
Which drill before tapping? Formula, chart for cutting and forming, fine threads.
Calculating spindle speed and feed rate for turning and milling
From vc to spindle speed, from fz to table feed and on to machining time.
Tightening torque for bolts – chart for 8.8, 10.9 and 12.9
Guide values for M6 to M16, reading the property class and the effect of lubrication.
General tolerances to ISO 2768 – table and examples
What “ISO 2768-mK” means and how much deviation is allowed on dimensions without a tolerance.
Calculating the developed length for bending
Blank length via the neutral axis, bend deduction and minimum bend radius.
Bolt circle calculation – hole coordinates
X and Y values for every hole, pitch angle, chord and start angle.
Taper turning – calculating taper ratio and setting angle
Taper ratio, the angle for the compound slide and when the tailstock will do.
Blog
- Checking an H7 fit bore – plug gauge, inside micrometer or dial indicator?
With Ø 20 H7 you have only 21 µm of tolerance. Which instruments are fine enough, what the plug gauge can do and why two-point measurement misses an out-of-round bore.
- M8 tap drill – 6.8 or 6.75 mm? What the rounding means
The formula says 6.75 mm, the drill set has 6.8 mm. Why both work, what 0.05 mm means for the thread and where the limit is.
- Technical handbook as an app – what a digital handbook needs
Book or phone? Which tables you really need, where an app can do more – and why you should still practise with the book for the exam.