Mount a bottle cage without support

Build a removable bottle cage as two independent prints. First derive a clamp from the bicycle tube. Then make a small male/female rail coupon. Finally use the same interface in the cage and mount. The print rule is concrete: every new roof layer needs material beneath it, so a flat roof becomes a peaked one.

Fit is a named relation {#fit-first}

Clearance belongs to both mating profiles. Name it before shaping either rail. The male profile is nominal. The female profile grows by clearance, not by an anonymous offset hidden in a cutter.

Make the frame interface {#clamp}

The clamp derives from measured tube diameter. frame_dia controls its inside radius; clip_t controls material outside that measurement. The opening makes the clamp printable and lets it flex onto the tube. Change diameter once, then read the derived radii before rendering.

Remove the unsupported roof {#roof}

The starter rail has a flat roof. Replace its roof cutter with the peaked cutter from the next step. Preserve base width, top width, height, and length: only the roof changes. The acceptance compares Core IR, not source spelling.

Reveal the peaked rail {#peaked-roof}

The rail coupon makes the fit visible. papa is nominal. mama derives width and height from fit_clearance, then adds a roof rise. Print both short coupons flat, slide them by hand, and adjust clearance only after observing the actual material and printer.

Use the complete mount {#full-cage}

Review clamp and cage as separately printable parts. The mount owns a male rail and frame clamp; the cage owns a female channel. Their shared names—base width, rail height, rail length, and clearance—are the contract. Test rail engagement without a bottle, then test retention under intended load. Geometry matching is not evidence of safe ride vibration behavior.