Calculators and charts
Drill sizes, thread series, Morse taper dimensions and densities are published standard values. Formulas are standard shop math: RPM = 3.82 x SFM / D, feed = RPM x flutes x chip load, tap drill = D - 0.01299 x % / TPI. Every calculator is labeled either as a published standard or as a shop starting point.
Surface speeds and chip loads are starting points chosen for hobby-size machines, deliberately conservative against handbook values that assume rigid industrial equipment.
Tool picks
Products are researched from published manufacturer specifications, listing details and patterns in verified owner reviews. We did not test them in person, and we say so on every roundup. Every product is a real, currently listed item; prices are pulled from live listings and change often.
Picks are weighted toward what hobbyists actually buy. Mini lathes around the $450 to $650 mark sell in high volume, while benchtop mills above about $1,600 sell in small numbers, which is why mills appear only as an expert tier.
Corrections
If a figure is wrong, tell us and we will fix it.