Jumpin' Frankenstein

  This year, we came up with a last minute animated prop, that turned
out to get a lot of scare action. Inexpensive, as big props go, and easy
enough to get going in a day. We had bought one of the big inflatable
Frankenstein's Monster "balloons" at Costco, for about $35. The rest of 
the material I already had, but none of it was particularly expensive.
I posted a note about it on the Methodz of Madness list, and received a
requests for pictures and step-by-step how-to...

  OK, I've got pictures. Since I already posted an ASCII how-to drawing,
I'm gonna be lazy for now, and copy it here.

  The basic "monster" was a 7 1/2 foot tall, lighted (green face and
hands), cartoonish Frankenstein's Monster. It's made of RipStop nylon, and
comes assembled with a fan/blower on a four-legged, foldup base. It has
long feet sticking out forward, and big mitts out to the side. When it is
pushed forward by the air piston, and slams to a stop at the end of the
travel, it rocks forward and the arms swing forward, like it's grabbing
for you...

   Side views:
    /    \
    |    | VERY simplified side view of inflated "monster"
    |    |
    |    |
  __|    |
 / Big   |
   /===\   Fan-and-support legs assembly, integral part of
  /     \    the off-the-shelf effect.
 =========   23" wide, 24" long, 3/8" plywood "shuttle"

 =================== 30" long aluminum channels, open edges facing
 =================== 30" long aluminum channels, used as spacers
 ====================================================== 72" long,
 ______________________________________________________ 24"wide,
 |  2x4 rails, laid flat (1.5" high)                  | 3/8" ply

    Top view of deck:

                        Channel and spacer mounted on top of deck
                      /           Pop-up sprinkler riser "piston"
  |                            /                      | 
  |                           /                       | 
  |                         =========      __         | 
  |                 ()======|       |-----(__)--      | 
  |                  \      =========       \         | 
  |                   \                      \ Air    | (from
  |                    \                      \ Valve |  dish
  ===================---\------------------------------  washer)
                          Bolt to attach to edge of shuttle board

     End view, assembled:

     /      |     \   Fan base, legs. (Four: front, back, sides)
    /       |      \
  <==================>  'C' channels, with shuttle between
  H                  H  Spacers
  ====================  Plywood deck
  |___|          |___|  2x4 rails (72" long)

    'C' Channel detail:

    ____ Drill 3/8" holes in top edge.
    ---- Drill 1/8" holes in bottom edge, and countersink.
   |    | Drill 1/8" holes in top of spacer piece.
   |    | Run 1.5" drywall screws through both pieces and
            3/8" deck, into 2x4 rails.

  My piston was made from a 9" pop-up sprinkler riser. The model I have
has 1/2" pipe threads on both the bottom (water inlet) and end of the
pop-up (for attaching the spray head.) I capped the top, after drilling a
hole in the cap for the attaching bolt. The inlet is adapted out to a
short vinyl hose, leading from a dishwasher solenoid valve. Air supply for
my haunt is through standard 5/8" garden hoses, plenty strong enough for
70-80 psi. Since the dishwasher valve has that useless second inlet
fitting, it needed to be capped-off to prevent too much air from blowing
out. Or so I thought.

  At 70 psi, there was still more than enough to slam the shuttle out to
the end of its travel, with the second valve inlet left open. Soooo, I
added a few feet of hose on the extra inlet, and directed it out to the
"guest end" of the whole works. The added noise really improved the
effect! The pop-up has a return spring in it, but it was way too weak to
drag the shuttle board back, so we added a couple of long, weak bungee
cords for return assist. The shuttle was a sliding fit in the aluminum 'C'
channel stock, so we hit the edges with a belt sander to trim them down a
bit, and smooth them, then liberally applied oil in the channel and on the

  It's been working for over a week, and made it through many, many
firings at Saturday night's pre- Halloween party. Great fun!

Now, for those pictures I promised:

Front view, full Rear view, full Mechanics Piston, extended Slide rail and spacer close-up Side view (smoky!) Unrelated, the Skull Fogger inside the Maze

Created on ... October 31, 2002