Nesting BNC Dipole Center and Winders

Pack together. Deploy separately. Walk out each antenna leg on its own winder, then join the winders at their spines and secure the center across them with a short rear strap.

This revision needs one LEFT and one RIGHT winder. Already printed the previous one-stud version? Keep one intact winder as the right and print only winder_left.stl. The center is unchanged. Two identical winders cannot make the intended joint with both studs engaged and the coils on opposite sides.

What to print

How the pair connects

Lay the right winder stud-up. Flip the left OVER about its long spine axis, like turning a page, so its stud points down and its winding region extends to the opposite side. This is a face-over flip, not an end-for-end turn while lying flat.

Bring the post-bearing faces together. Both studs enter the opposite holes; press straight together until the spines touch. The coils stay on opposite sides. The 6 mm studs rise 8 mm above their frames and project 3 mm through the opposite frame. Rounded roots and relieved hole mouths ease seating.

The two connections resist pivoting; the strap retains the bundle. To separate, pull straight apart by a little more than 8 mm. Avoid peeling or twisting against the stud roots.

A short strap around the back

Place the 90 × 39 × 23 mm center crosswise, leaving wire tails relaxed. Its 14 × 3 mm slots accept roughly half-inch hook-and-loop strap up to 2 mm thick.

Thread an end through each slot. Route the middle over the coils and around the back, then fold and fasten the ends at the slots. Use closures that engage when folded back. This forms an open U with the center’s front clear. Fit the length to your wound coils; separate coil ties retain each leg’s wire.

Deploy by releasing the strap, lifting off the center, separating the winders and walking out each leg before hoisting.

BNC fit and useful parameters

Default BNC opening: 9.50 mm. Start with the tight coupon. Print foot-down with holes upright, at 100% scale using the center’s settings. Choose the smallest opening that accepts your connector without force and lets its D-flat seat.

Extract the source ZIP with folders intact. Open models/ham_radio/nesting_dipole/nesting_dipole.scad, adjust, render (F6) and export STL. Existing STLs are fixed meshes.

The shared BNC Dipole Center uses strap_slots=true, balun_mount=false here. Its equivalent BNC setting is bnc_clearance=-0.10. Taller balun versions have not been validated in this bundle. The README covers wire, terminal and hanging-hole adjustments. The 40m/80m presets affect wire previews, not printed geometry.

Printing and hardware

Print broad backs flat, both studs up and BNC shelf upright, as supplied. Starting settings: PETG, 0.20 mm layers, five walls, 100% infill. Dry-fit the bare pair and BNC before winding.

The included center guide covers the Amphenol 31-221-RFX connector, M3 terminals and wire weave. Weave before crimping rings and leave slack at the terminals. CAD checks cover both stud engagements and straight insertion; physical fit, strength and loaded packing still need print trials.

Winding profile derived from K6ARK Wire Antenna Winder — UL Wireframe Model by Adam Kimmerly, K6ARK. Nesting arrangement and center by Robert Jackson, N1RWJ. Licensed CC BY-NC-SA 4.0; attribution included in the source ZIP.