Twopi Forge

Twopi Forge is the complete bench companion for amateur radio operators and RF electronics builders who wind their own toroidal inductors. From computing the exact turn count and wire length for your next low-pass filter or choke balun, to photographing your finished coil and getting a pass or rework verdict, Twopi Forge covers every step of the winding bench workflow — offline, always. The Wind calculator covers 18 real toroidal cores — T-37 through T-200 in iron-powder mixes 2, 6, 10, and more, plus ferrite cores FT-82, FT-140, and FT-240 in mixes 31, 43, and 61 — across 8 winding styles including bifilar, trifilar, twisted-pair, coax-wound, and sectional. Dial in a target inductance in microhenries or a reactance in ohms at your chosen ham band, and the engine returns turn count, recommended AWG wire gauge, cut wire length, window fill, and a to-scale 2-pi gauge diagram showing exactly where each turn sits around the toroid. The Check tool turns your camera into a precision winding inspector. Place calibration circles on a photo of your wound coil, tap each turn around the ring, and let the geometry engine measure actual pitch, spread, lead gap, and deviation from plan. A colour-match check confirms you grabbed the right core mix. Every check is saved to the build log with a deviation sparkline so you can track improvement across rework iterations. The Chart reference library keeps you from reaching for a databook: AL tables for all 18 cores, full mix profiles with frequency ranges and coat colours, winding-style diagrams, a fault guide covering 9 common defects and their fixes, and a bench-kit checklist. Ten pre-loaded build templates — a choke balun, a 9:1 unun, a Guanella 4:1 balun, a QRP PA output filter, and more — let you see real-world winding plans straight away. No account needed; no network required.