A small, independent set of calculators and guides for people working in a wood shop or a metal shop. Formula on every page, no account, nothing to buy.
Furniture and cabinet makers, hobby woodworkers, machinists, welders and anyone setting up shop machines. The tools cover four kinds of job: laying out joints and cut lists, setting up saws, routers and lathes, buying and fastening lumber, and choosing starting settings for drilling, tapping and welding. There are currently 46 calculators; 20 of them are full guides with reference tables and worked examples.
The Tool Mill is not affiliated with any tool maker or retailer, does not sell anything, and no calculator steers you toward a product.
A topic gets a page when the job has a real formula you can check by hand and inputs you can measure yourself — a wheel diameter, a slot width, a board thickness, a rod diameter. Topics that would only repeat someone else’s chart, or that need a structural or code decision, are left out. Pages that turned out to be too thin to be useful have been folded back or removed from the index rather than padded.
Every number in a reference table or worked example on a guide page is produced by running the page’s own calculator code with those inputs, then compared with the published result. If the calculator and the text ever disagree, the page is not published. When a formula is corrected, the tables and examples are regenerated from it.
Where a formula has a well-known independent form — the compound miter angles for a splayed box, the 75% tap drill rule, the belt length around two pulleys — the calculator’s output is also checked against that form. Lookup tables (screw root diameters, drill sizes, insert pilots) come from published dimension charts, and the page says so.
Inputs are checked for the mistakes people actually make: a blank or zero field, a negative length, a clearance larger than the slot, a bit larger than the circle. Instead of printing a confident wrong number, the calculator says what is wrong.
A formula only knows what you type. It cannot see a dull blade, a worn tire, a flexing frame, wet wood, a loose pivot pin or an out-of-tram mill head. Speeds and amperages are starting points to make a test cut or a test bead with. Every page lists the main assumptions it makes, and where a manufacturer publishes a figure for your exact blade, bit, insert or electrode, that figure wins.
These pages are not engineering calculations, building-code rulings, welding procedure specifications, or a substitute for a machine’s manual or safety training.
If you find a wrong number, a confusing input, or a result that does not match your shop experience, please use the contact page. Reports are checked against the formula and the worked examples, and the page is corrected if needed. A clear description — the inputs you used and the result you expected — makes it quick to find.
Marine calculators (fuel range, anchor rode, dock lines) live on a separate site, The Boat Mill. The Tool Mill sticks to the shop.