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The Flying Crank Ghost

An amazing effect for next to nothing!

[Introduction]-[Parts List]-[Chassis]-[Puppet]-[Finished Product]

Introduction
     Last year, after the party was over and we were taking the garage haunt down, my haunting partner Derek said to me, "Next year, let's do animatronics." I didn't take him seriously then, but early this summer we decided to "go all out." I joined the Halloween-L mailing list, and a series of posts (me asking for advice and getting lots of it) convinced me to take the plunge into my first self-animated prop.
     The Flying Crank Ghost was invented by Doug Ferguson of Phantasmechanics. Doug's version of the FCG (Scroll down his page to find it) is amazing, but the costs involved with the aluminum mechanism were somewhat out of an unemployed 16-year-old's reach. So, I set out to construct a somewhat less heavy-duty, but still operational (an much cheaper!) version of the flying crank ghost.
     Someone on the Halloween-L mailing list directed me to All Electronics, where I bought a motor that is much cheaper than the one Doug recommended, but does the same job. My other main changes to the original plans, using wood and unbent coat hangers instead of aluminum for the chassis frame, took the cost way down. My version is completely different in design, but relies on the same mechanical principles of the original.
Parts List
Chassis
ItemPrice
6 RPM 12V DC Gearmotor$12.00
5 feet of ~1"x2" wood~$2.00
3 small pulleys$4.50
2 STRONG wire coat hangers--
Assorted screws--
1 large washer--
1 Plastic bushing--
Lots of string???
2 Rubber bands???
Total should be:<$20!
Puppet
ItemPrice
Under Construction!
Building the Chassis

The finished chassis
Note: Click on any photo to enlarge it!

I started out with the 6 RPM 12V DC Gearmotor from All Electronics. I slid off the black protective cover, to expose the motor contacts (much easier to work with than the extra wire). The motor
Since the FCG is basically a three-point marionette, I decided to construct a T-frame out of wood, with the top of T 30" long and the height of the T 20" long. (The crank, built of 3/16" thick coat hanger wire, is also shown here.) T of the chassis
I chose to build the T in two layers for several reasons: First, overlapping adds strength, and second, the extra thickness compensates for the unneeded length of the motor shaft. All measurements necessary to build the T are on this image. Dimensions of chassis
To accommodate the motor, I drilled a 1/2" hole (for the shaft) and then a 1" hole (for the motor) in the piece that makes up the top layer of the T. I used a Dremel tool to enlarge the 1" hole untile the motor fit snugly, and then I bored out the space between them as well as the edge of the 1" hole on the top side (see picture) so the motor could slide all the way on. Where the motor goes
This picture shows the T bottom up, with the motor in position. The shaft is about 2" from the top of the T, but the exact position is unimportant. As this picture also shows, I drilled a 3/16" hole in the motor's shaft while it was in a workbench-mounted vise (not shown). The motor in place
Next, I bent a 16" long piece of 3/16" (very strong) wire coat hanger into an L shape 2" from the end. I slid the long end through the hole in the motor shaft, and did not secure it until I knew how much motion I wanted to generate. I placed the bushing on the short end and made another bend to secure it. Motor and crank
In case you were wondering what the bushing is for, its purpose is to make this wahser spin freely. This prevents the 3 strings that are tied to the holes drilled in the washer from tangling or twisting as the crank revolves. The washer should fit snugly on the bushing, so it doesn't fall off. The washer
I suspended a pulley from each end of the T frame by drilling a hole through the wood about 1 inch from each end and dropping T shapes from 8" coat hanger segments through, then bending them into hooks for the pulleys. 1 of 3 pulleys on its hook
Now, the 3 strings each went from the horizontally revolving (but not rotating) washer at the end of the crank, to pulleys that each converted the crank's motion to non-synchronized vertical bobbing movement. At this point, I was basically done, and basically happy with the chassis. The finished chassis
I decided to test the chassis by mounting it to the fortunately exposed ceiling structure of the workroom. Before I did this, I temporarily removed the crank from the motor and secured the motor with 2 rubber bands stretched from the screw on 1 corner of the motor, under the chassis, and back up to the opposite corner. The bands can be seen in this picture, as can the loops of twine that suspend the T frame from 2 nails and a hook in the ceiling, and the alligator clips and coord from a 12V AC adapter that I had lying around and used to power the motor. The blue pole on the left is a blacklight that I stuck in a mass of rope hanging from the ceiling and used to test my puppet as I built it.
To test the chassis, I plugged in the AC adapter, hooked up the alligator clips to the motor leads, and watched my weighted strings bob up and down...all for under 20 dollars!
The mounted chassis, from below
This concludes the Chassis section. If you have any questions, comments, thoughts, information, inspiration, or plain old desire to contact me, feel free to email me at mooseboy@optonline.net.

[Back to Top]
Crafting the Puppet
Under Construction!
The Final Effect
Under Construction!