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Discussion Starter #1
I was asked for a tutorial on my swaying zombie: http://www.halloweenforum.com/halloween-props/132032-opened-back-door-find-swaying-zombie.html There are other talented folks here who have made them, but I copied mine from CycloneJack, as I liked the lurching movement his had: http://www.halloweenforum.com/halloween-props/125470-swaying-ghoul-zombie-done.html

Here he is before getting gory:
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Materials Needed:

Drive mechanism:
12v gear motor, anywhere from 6rpm to 18rpm
12v power supply (wall wart transformer)
hole-punched steel strap for garage doors (Home Depot)

Zombie:
about 8' of 3/4" PVC
four 3/4" PVC 45s, one 90, one cross
about 8' of 3/4" EMT (cheap steel conduit, Home Depot)
two 2' pieces of 5/8" steel rod or rebar
four 3/4" hose clamps
3/4" plywood, 1'x3' should be enough
head (a mask on a milk jug would work, but I used a mannequin head from displayimporter website)
hands (I used realistic ones fro displayimporter)
padding to fill out (I used 2liter soda bottles and pool noodle)
clothes to dress him (I used my old stuff so I sized him to match me)


Optional Materials:
Motion Detector Floodlight (about $15 at Walmart or Home Depot)
 

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Discussion Starter #2
Head construction

I used a mannequin head from the displayimporter website for its realism, but its fiberglass and rather heavy about 4lbs, which is a chore for the motor to swing around. A mask on a wigform or milk jug would be much easier and lighter.

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I used a holesaw for the bottom hole, the holesaw and a burr bit to cut the armpit holes as they are elliptical, and the holesaw to make the corners of the back window, with a jigsaw to connect the holes. I had to cut-fit-cut-fit again to sneak up on the armpit holes so they would line up to the cross and be tight.

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Discussion Starter #3
Hip construction

The hips are the mounting point for the drive mechanism and where the legs attach. I measured myself at waist/hips and used the jigsaw to cut the 3/4" plywood. I used a holesaw to cut the leg holes for the conduit; I like these holes to be somewhat loose to allow flexibility in the stance width. I drilled a 1/2" hole centered between the leg holes for the driveshaft, which is a 3/8" bolt. I cut two pieces of the garage door strap and bolted them over the hole, one above the board and one below, with the mounting bolts boing thru both pieces. This gives a durable, low-friction, precisely vertical bearing surface for the driveshaft bolt. The driveshaft gets a lot of side loading and it shouldn't wobble or the motor connection will fail. Another piece of strap makes the arm. The driveshaft bolt has a nut and washer under the arm strap to keep it high enough, and under the hip board it gets a washer and two nuts that will be locked together as jam nuts with enough slack for the bolt to turn easily. The moving end of the arm strap gets a bolt with two nuts at the top for the PVC spine to slip over. I'm sorry I didn't take enough pics during this phase.

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Discussion Starter #4
Spine Pivot Support

I used more 3/4" plywood to make the pivot support for the zombie's spine. It's about 6" above the hips. The lower the pivot hole, the greater the swing and weight against the motor. I made a 1-5/8" hole for the pivot even though the PVC is 1-1/8" outside. The oversize hole is the key to why CycloneJack's zombie has the lurching sway. The zombie head/torso will flop from side to side in the pivot hole. The hip board is resting on hoseclamps on the leg conduit. Hoseclamps above the hip board will keep the legs attached when moving it around, and allow enough slack for a variable stance width. EMT conduit is great because it is really cheap, light, strong, and corrosion-proof. The leg conduits slip over 2' long pieces of 5/8" steel rod that I hammer halfway into the ground. This way I can easily move him to other locations as the stance width isn't critical, and it's strong enough for wind. I now moved the bolt on the crank arm inboard two holes because I found the outer hole allowed the torso to flop too far.

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This was a test mounting of the motor. If you use a wiper, vent, or monster purposed motor you would have it easier. I used this 12v gearmotor I got from American Science & Surplus for only $8. The problem is attaching a driveshaft. It has two outputs, one that is 5/16" fine thread, and one that is a round shaft with no flats. In this attempt, I hose-clamped a piece of fuel line on the smooth motor shaft to the drive bolt. I thought this would allow some flex to take the stress off the gearmotor bearings since the driveshaft will wobble a little. It gripped the motor shaft well, but not the threaded drive bolt.

IMG_2983resized.jpg
 

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Discussion Starter #5
Anti-spin control

This pic shows the wire that keeps the zombie torso from spinning while the crank pivots it around. I used some heavy coathanger wire. You have to get the zombie's spine cut to length by test-fitting him, then slip it over the crank bolt. Then you mark where the spine meets the top of the pivot hole at the high and low points. I drilled a 3/8" hole thru the spine at the top and bottom points then connected them by grinding so they are one slot on each side for the anti-spin wire to go thru. A 3/8" slot is pretty wide for the wire, but this ensures it doesn't bind and adds a little slack for more lurching floppiness. The trick is the top of this slot needs to be low enough that the zombie torso's weight is on the wire, not the crank bolt, or it may flex the crank arm down and jam, as well as adding stress to the crank bolt. I also welded the nuts & bolts because I don't want them to loosen in use, this was probably not necessary if you tighten them good, but I have a MIG and too much Murphy's Law experience. You could use Loctite, epoxy, or JB Weld if you are as paranoid as me.

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Discussion Starter #6
Slightly better motor mount

This part will be easier for you if you are slightly smarter than me and use an appropriate motor. YOU would just attach your wiper motor to the hip board and screw a crank arm into the drive hole. After the rubber connection failed, I fell back to my original plan. This was to weld a 5/16 fine thread nut onto the drive bolt for the threaded motor shaft to thread into, with a nut on the motor shaft to act as a jam nut. I didn't want to weld directly to the motor shaft for fear of killing my beloved $8 gearmotor. Naturally the nut welded on a little crooked, despite much careful jigging and quick welding of opposing sides followed by forceful straightening while hot. I estimated this crookedness would quickly wipe out the gearmotor bearings trying to fight this unyielding wobble. So I used a couple of steel 90 degree brackets to block the motor from spinning, but with enough gap that the motor can wobble without stressing the bearings. The brackets are not attached to the gearmotor, the gearmotor is hanging from the drive bolt. A really hacked up solution to poor motor choice leading to reliance on poor welding skills! Start with a good gearmotor!!!

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Discussion Starter #7
Wrap-up

Sorry no pics of the arm building but it's simple and same as CycloneJack's. I cut the PVC sticking out of the armpit holes to length and put a 45 on the end, angled forward and down, with two 3/16" holes drilled near the ends. The upper arms are 12" or so PVC with two 3/16" holes at the top end. They hang from the shoulder holes by zipties, loosely so they can swing freely. The elbows are a 45 on one side, and a 45 plus a 90 on the other. This is what CycloneJack did and I really liked his zombie's arms positions and how they contributed to the movement. Forearms are about 12" PVC, and I ziptied on mannequin hands from displayimporter. To fill out the arms and legs I used mostly 2liter soda bottles, with holes in the top and bottom, and a split down the side so I could pop them over the PVC or conduit. Some pool noodle type stuff goes across the back of the shoulders to bulge it there. You can see a test scar on his chest I made with ripped up red fabric ribbon and Gorilla Glue.

IMG_3054resized.jpg
 

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Discussion Starter #8
Optional Enhancement

I power mine thru a motion detector pulled from a cheap floodlight, on the Test setting so it runs day or night each time motion is detected, but only for 5 seconds. I don't want to burn out the motor and I think this is a little more realistic. Now I have decided to add a green light to illuminate him when he is running, so, DUH, I would have been better off leaving the motion detector attached to the floodlight. You could put a bulb in one floodlight socket and a screw-in plug adapter in the other to accomplish this easily. If you choose a gearmotor that moves a little faster than my 6rpm, say 10-15rpm, I think it would be better. I am still making him look damaged so I will post a finished pic here soon.
 

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Discussion Starter #11
That is a GREAT idea, I could see him with a mug of rum in his hand and a parrot on his shoulder wobbling trying to hang on! AAARRR, still got me sea-legs!
 

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Funeral Crasher
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Your zombie looks excellent and that's a great tutorial!
Very nice movement.
I think I used that same gear motor on my swaying zombie. Is it the one that sounds like a thrashing machine when it's running?

To attach my crank, I screwed a 5/16 nut halfway on the motor shaft, then screwed a 5/16 bolt into other half of the same nut. I used another 5/16 nut as a jam nut and lock washer on both sides of theoriginal nut to keep it from unscrewing.
I think it's gonna work. He'll be out in the yard tomorrow!
 
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