Practical Engineering Tools
Drafter Toolbox
Practical engineering tools for calculations, checks, conversions, references, generators, and the workflow around them.
Engineering Copilot
Mechanical engineering copilot for DFM, machining, and manufacturing questions.
Drawing Redliner
AI drawing review: upload a drawing and get structured redline feedback.
Fixed Fastener Formula
Calculate the required positional tolerance for clearance holes in a fixed fastener assembly. Applies the GD&T fixed fastener formula T = H − F to determine tolerance distribution between mating parts.
Tolerance Stack-Up Calculator
Build a manual 1D tolerance stack-up, 2D hole alignment check, or fastener clearance workflow with STEP assembly context, worst-case, RSS, Monte Carlo yield, and contributor impact ranking.
Thread Engagement Calculator
Find the minimum thread engagement for a bolt to break before its threads or the tapped threads strip, from the thread size and the two materials, by the Machinery's Handbook method. Preliminary (PDR-level) tool.
Bolt Torque Calculator
Find the recommended and maximum install torque for a fastener and the resulting bolt tension (preload), from bolt size, proof strength, and nut factor K. Preliminary (PDR-level) tool.
Clearance Hole Chart
Find the clearance hole and drill for a screw or bolt at close, normal or loose fit: metric M1.6 to M64 to ISO 273, inch #0 to 1 1/2 to ASME B18.2.8.
GD&T Cheat Sheet
The symbols, datum rules, and feature control frame anatomy on one page. The reference to keep open while you dimension.
Tap and Drill Chart
Drill sizes for every common inch and metric thread, with thread engagement percentages so you can pick a size instead of guessing.
Weld Symbol Chart
Weld symbols and what each one actually asks the shop to do, including the ones people draw wrong most often.
CNC Design Guide
How to design parts a machinist can actually cut: tool access, internal radii, wall thickness, and the tolerances worth paying for.
Sheet Metal DFM Guide
Bend radii, relief cuts, hole-to-bend distances, and the flat-pattern math behind them. Written for parts that come back right the first time.
Injection Molding DFM Guide
Draft, wall thickness, ribs, bosses, and gate placement, plus what each one costs you in tooling if you get it wrong.
