Crop turret, the camera-aimed water jet
A pan/tilt head on a staked post. Its camera finds a deer, a rabbit or a raccoon in the berries, the head swings onto it, and a short burst of garden-hose water sends it off. Never at a person. It is built from a 3D printer's leftovers: both motors, the belts and the wheels. This is the checked design; nothing has been built yet.
The meshes are exported from the same OpenSCAD file the checks read and the slicer will print. Red parts are printed in ASA, and so are the grey faceted covers (their final colour isn't chosen). Steel, black and blue parts are bought. The belts change shape from the model's own keyframes.
What it does
One unit guards a circle of about 15 m radius, the same as the commercial motion sprinklers, so a large patch takes two or more. The camera's frames go over the farm's own network to a small AI accelerator in the shop, which finds the animals. When an allowed animal is seen in several frames in a row, the head turns onto it and fires a random pattern of one to three pulses, each no longer than 3 s, then waits 20 s. It sends a phone notice and a snapshot each time it fires. Nothing about it needs the internet.
The research is plain that a scare works for days to weeks before the animals get used to it, and the ones that last are triggered by the animal and vary what they do. So the turret is one layer, alongside the fence and the netting, and it gets moved every few days.
The rules it keeps
No shot with a person in view. A person anywhere in the frame blocks firing until 30 s after they leave, and so do a dog, a vehicle and anything the detector can't name. A maybe-person counts as a person. A person who appears mid-burst closes the valve at the next frame.
The valve can't stay open. Every opening has a deadline in software. In hardware, the valve's coil gets power only through the e-stop, a relay that drops out if the control program freezes, and a timer that cuts it at about 4 s whatever the software does. A key switch on the box arms it, and the red e-stop on the lid cuts everything.
Birds by species, never as “bird”. An eagle is a bird, and disturbing one is a federal offence, so the generic classes can't be set as targets. In Wisconsin the infrared lamp stays off in the fall shining hours, and deer mode goes off for the gun season. The line of fire is limited per site so the jet never reaches a road or a neighbour's land.
Built from a printer's leftovers
When a 3D printer is rebuilt, its spare parts can become this: the two Z-axis stepper motors drive pan and tilt, the V-wheels carry the turntable, and the GT2 belts and idlers make an omega drive onto a printed 80-tooth drum. Everything else is standard: a ¾ in EMT stake, a normally-closed 24 V solenoid valve, a brass nozzle, 608 bearings on a hollow tilt axle that the hose runs through, and a Raspberry Pi wide camera with an 850 nm lamp for night. The control box on the post is a stock NEMA 4X enclosure with cable glands.
The water-carrying parts come off on two hand-tight hose unions and come inside before the first frost. Like the rest of the fleet, it works in the warm season only.
Choosing a look
These four are pictures, not drawings. An image model painted them from the model's render, with the layout held fixed; the finish, covers and fittings are its ideas. Chosen 2026-11-02: C's faceted covers and D's clipped cable runs. Both are now in the checked model above: hoods over the valve, the tilt motor and the camera, three snap-in cable clips on the yoke, and C's skirt, twelve facets round the pan drive in two halves that lift off. Hide covers shows what they enclose.
Where it stands
The head and the post are drawn and checked, and the control logic's safety rules each have a test. Next: the counterweight change, then measuring the real motors and wheels off the printer to replace the assumed sizes, then a first print. A working unit in a field is at least six months away.
Design basis: drumlin docs/TURRET.md, turret/head/pan-tilt.scad and turret/post/post.scad, at 0238d06 · 2026-11-02. The turntable and the omega drives are rows from the shop's design library, used as they are. Figures marked as research come from sourced findings; the rest is the design's own arithmetic.