Prop Building 101 Part 4: The Flying Crank Ghost

A flying crank ghost is a head, two hands and a lot of cheesecloth, hung from a slow motor. The head stays put. The hands are tied to a crank, so as it turns one arm lifts while the other drops, and the cloth between them rolls and flaps as if the thing were swimming through the air. It needs no electronics beyond a switch, it runs all night, and in a porch or window with a little light on it, it reads from the street better than most store animatronics.

What follows is our own build. The mechanism has been passed around the haunting hobby for years; the dimensions and choices below are ours.

How the Mechanism Works

Three lines hang from the top of the frame:

• The head line is fixed. It ties to the frame a few inches in front of the crank and holds the head at the height you want.
• Two hand lines tie to the crank, one to each throw. The crank turns on a horizontal shaft, so each throw travels a vertical circle, and the two offsets are set opposite each other: when the left hand is at the top of its circle the right is at the bottom.

The cloth hangs from the head and drapes over both hands. Every turn of the crank pulls the hands up and around in turn, and the fabric follows them a fraction of a second late, which is what sells the effect. The motor never touches the ghost; it only moves two strings.

Materials

• A frame or a solid overhead mount. A PVC tee stand or crossbar from Part 1, or a porch ceiling joist. The load is light, which is what keeps PVC reasonable here.
• A slow motor. A rotisserie motor, or a DC gear motor with its own power supply (both covered below).
• A crank. For a rotisserie motor, a short length of 5/16” square rod in the drive socket with two arms fixed to it. Our version uses two strips of 1/2” plywood about 4” long. Each gets a 5/16” square hole at one end (drill a round hole, then file it square so it grips the rod) and a small hole for the line near the other, and the two are set 180° apart and glued or pinned to the rod. A bent steel rod with two opposite offsets does the same job.
• A head. A foam wig head is the easy choice; it’s light and takes a skull mask or a papier-mâché face. A monster mud or corpsed skull head from Part 2 or Part 3 works if you keep it light.
• Hands. Anything light with a hole for the line: foam or plastic skeleton hands, or knotted cloth.
• Line. Clear 20 lb monofilament. The listing gives this spool a 0.016 in. diameter, thin enough to disappear against a dark background.
• Cloth. White cheesecloth for a porch under a roof; see the fabric section before you pick it for anything near a light.

Choosing the Motor

Rotisserie motors are the standard pick because they’re slow, cheap, run on household current and already have a mounting system. Onlyfire’s spec table for its Weber kettle ring kit lists a rotisserie speed of 2 to 3 RPM and a weight capacity of 20 lb (Onlyfire 6025 ring kit). Its standalone replacement motors fit “standard 3” motor mounts and 5/16” square drive rotisserie spit rods” (Onlyfire replacement motor), and the stainless version lists “up to 20 lbs capacity” and “a 36” power cord” (Onlyfire stainless motor). A ghost weighs ounces, so capacity isn’t the question.

At 2 to 3 RPM a full cycle takes 20 to 30 seconds. That reads as a slow, drifting float, which is what most people want. If you want a more agitated ghost, a longer crank arm gives bigger motion at the same speed.

What none of those Onlyfire pages states is an outdoor or wet-location rating, or a certification from a testing lab. The black motor’s page advertises an “easy on/off waterproof switch.” A waterproof switch is a switch; it isn’t a rating for the motor in rain. Because the ghost’s cloth hangs right off the crank, we’d only use a motor that carries a testing-lab mark (more on that below), and we treat every rotisserie motor as a sheltered-location device.

DC gear motors trade household current for a low-voltage supply, which keeps household current away from the cloth. Pololu’s micro metal gearmotors are the example we can document. In the 6V low-power version with a 1000:1 gearbox, Pololu lists a no-load speed of 13 RPM and an extrapolated stall torque of 5.5 kg⋅cm (Pololu micro metal gearmotors). That’s several times faster than a rotisserie motor, and Pololu is blunt about load: “The recommended upper limit for instantaneous torque is 2.5 kg⋅cm (35 oz⋅in) for the 380:1 and 1000:1 gearboxes,” and “a general recommendation for brushed DC motor operation is 25% or less of the stall current.” It also notes these motors “can run at voltages above and below their nominal voltages; lower voltages might not be practical.”

In practice that means a short crank (an inch or so), a very light ghost, and a faster, busier flap. It also means you’re choosing a power supply and wiring the motor yourself, which is a small electronics project rather than a plug-in. We’d start with a rotisserie motor unless the ghost has to run from a battery or sit right against the fabric.

Building It

1. Mount the motor to the frame or joist with its drive shaft horizontal, parallel to the ceiling or crossbar, so the crank arms turn in a vertical circle and clear everything around them. A rotisserie motor slides onto its 3” mount; a scrap of plywood cut to take that mount works if you don’t have the bracket.
2. Fit the crank. Push the square rod into the drive, fix both arms to it 180° apart, and tie a hand line to the outer hole of each arm.
3. Hang the head on its fixed line, tied a few inches in front of the crank and centered between the two arms, so the hand lines fall just behind the shoulders.
4. Set the hand heights. Each hand rises and falls by twice the crank arm length, so 4” arms move the hands about 8”. Tie each hand so it hangs a little below shoulder height at the bottom of its circle; at the top it reaches about head height. Longer arms give a bigger reach if the motor and frame have room.
5. Dress it. Drape one long piece of cloth over the head and both hands for the body, then add torn strips hanging from the hands and the hem. Rip the cheesecloth rather than cutting it; torn edges read as rags.
6. Run it before you install it. Watch several full turns for a line catching on the crank or cloth wrapping the rod. Trim anything that reaches the moving parts.

Power: GFCI, Listing Marks and Cords

The CPSC’s decorating advice is written about lights, and it applies to a motor on a porch just as well: plug outdoor decorations only “into a ground-fault circuit interrupter (GFCI)-protected receptacle or a portable GFCI,” and “Only use lights tested for safety by a nationally recognized testing laboratory” (CPSC).

A nationally recognized testing laboratory, or NRTL, is an OSHA designation. OSHA says the lab’s certification mark “signifies that the NRTL tested and certified the product,” and that “each NRTL uses its own unique registered certification mark(s)” (OSHA NRTL program). A listing’s claim is a reason to shortlist a motor; the mark on the housing or plug is what confirms it. A crank ghost hangs cheesecloth inches from the motor, so there’s no “well away from combustibles” option: if the motor you receive carries no testing-lab mark, return it and use one that does.

Our setup for a rotisserie motor:

• Under a solid roof. A porch ceiling or deep eave, not an open yard. Rain on a motor with no wet rating is the failure we’re avoiding; our weatherproofing guide covers covering connections.
• On a GFCI. Use a GFCI-protected outlet, or a plug-in GFCI adapter at an indoor wall outlet. The Southwire portable GFCI we recommend elsewhere is described in its listing as suitable for indoor use, so it goes at the wall inside, not out on the porch.
• Cords routed, not trapped. OSHA’s flexible cord guidance lists how cords get damaged: “by door or window edges, by staples and fastenings, by abrasion from adjacent materials” (OSHA). Don’t close the front door on the cord, and use clips rather than staples.

Pinch Points: Mount It Out of Reach

A 2 RPM crank looks harmless. OSHA’s guide to machine safeguarding disagrees with that instinct. It describes rotating parts as motion “that may grip clothing or otherwise force a body part into a dangerous location,” adds that “Even smooth surfaced rotating machine parts can be hazardous,” and notes that “Projections such as screws or burrs on the rotating part increase the hazard potential” (OSHA 3170, Safeguarding Equipment and Protecting Employees from Amputations, p. 7). Its in-running nip points develop “when two parts move together and at least one moves in rotary or circular motion” or “when one part moves past a stationary object” (p. 8).

That’s workplace guidance about industrial machines, and a rotisserie motor is not a press brake. But the description fits a crank with a set screw and bolt heads on it, turning next to a frame member, very well. Long hair, a scarf or a costume sleeve wound onto the rod doesn’t need much torque to hurt someone. So:

• Mount the motor and crank above reach. On a porch, that means at the ceiling, not at head height on a stand in the walkway.
• If the ghost has to sit lower, box the crank in with a scrap-wood or cardboard cover that leaves only the lines coming out of the bottom.
• Unplug the motor before you touch the crank, the lines or the cloth.

Fabric, Lights and Exits

The motor is a small fire risk. The cloth is a bigger one. NFPA’s Halloween tip sheet says to “Keep all decorations away from open flames and other heat sources like light bulbs and heaters,” and that decorations “are the first thing to ignite in more than 800 reported home fires each year,” with nearly a third started by a candle (NFPA Halloween Fire Safety Tips). A CPSC report estimates that candles were associated with an annual average of 5,600 fires from 2017 through 2019, across the whole year rather than just October (CPSC, 2022).

• No candles, lanterns with flames, or hot bulbs near the ghost. A moving ghost sweeps a bigger volume than a still one; measure clearance from the widest point of the arm swing.
• Light it from a distance. Aim a spotlight or blacklight at the ghost from several feet away rather than tucking a fixture inside the cloth. Our blacklight setup guide covers which materials fluoresce and how far to keep UV fixtures.

On fabric choice, the only federal flammability data we have is for clothing, not decorations, so read it as a guide rather than a rating. CPSC’s staff fact sheet on the clothing textile standard (16 CFR 1610) says years of testing show two groups “consistently pass as Class 1,” the normal-flammability class: plain surface fabrics “weighing 2.6 ounces /73 grams per square yard or more,” and fabrics made entirely from “acrylic, modacrylic, nylon, olefin, polyester, and wool.” It names “sheer rayon or silk” among fabrics likely to land in the faster-burning classes (CPSC 1610 fact sheet). Cheesecloth is sheer cotton, which puts it in neither of the consistently passing groups. Applying that to a Halloween ghost is our inference, but it’s why we use cheesecloth only where no heat source can reach it and look for fabric labeled 100% polyester when the ghost will hang near lights.

Exits. NFPA’s other rule for decorations: “keep exits clear of decorations so nothing blocks escape routes.” A ghost in the front doorway is a classic spot and a bad one if its lines or cloth hang into the opening. Hang it beside the door or above the swing, high enough that nobody walks into the hem.

Getting It Up There

Of the roughly 3,200 Halloween-related injuries treated in emergency rooms each year, the CPSC says “25% were due to falls while putting up or taking down decorations, tripping on costumes or walking while trick-or-treating” (CPSC, 2022). Mounting a motor to a porch ceiling means working overhead on a ladder with both hands busy. Our skeleton posing guide covers ladder setup, including OSHA’s portable ladder guidance. Screw the mount into framing, not into a soffit panel or drywall, and have someone hold the ladder and hand things up.

For a crank ghost indoors or on a long-term display, our animatronic repair guide covers the power and weather problems motorized props share.