Christmas Jumping Jack Bears

It was time for some new Christmas decorations. This time they had to be animated. An oversized jumping jacks seemed like the perfect thing.Jumping jacks are the toys with a character on a stick. The arms and legs leap up when you pull a string.

3/8" Outdoor plywood - 2 bears fit in one 4x8 sheet

1/8" Plywood for arm/leg reinforcement

1/4" Plywood for post to body mounts

1" Rigid foam insulation

2" x 2" x 5' Pine lumber - 1 per bear

1" x 1" x 32" Angle iron (L) for base - 1 per bear

2" x 3" x 32" Pine lumber for base - 1 per bear

2" ID x 2" ID x 10-12" Steel tubing for base, 12ga to 1/8" wall thickness - 1 per bear

1/4" Carriage bolts, plain nut, nyloc nuts - 9 per bear

1/4" Plain washers - 17 per bear

1/2" OD, 1/4" ID 1" long nylon spacers - 6 per bear

Nylon rope

Camping stakes - 4 per bear

Old cotton sheets or material to cover arms and legs

Water proof wood glue

Urethane (Gorilla) glue

Paint

Outdoor varnish

Masonry water proof paint

Linear Actuator - 1 per bear. See separate Instructable for homemade one.

Tools

Jigsaw

Foam cutter

Paint Brushes

Drill

I upscaled the patterns to fit each on a 4'x4' piece of plywood along with a 2" grid for alignment.

Print out all pattern pieces and tape all pieces together. Some of the pages are unneeded so preview before printing.

The best way to transfer it onto the wood is to lay down a heavy pencil line on the back of every line. Once you turn it over and place the pattern on the board, trace over all the lines on the front.

The graphite on the back will be transferred onto the wood. Trace the main body on plywood and trace arms and legs on ridged foam insulation.

The foam makes the arms and legs very light so it is easier for the motor to move them up and down.

A jigsaw for the plywood and a foam cutter for the foam were used to cut out the pieces. You can use a handsaw to cut the foam but it creates more of a mess. Put a thin layer of water proof wood glue over the front surface and sides of the foam pieces and stretch a piece of material over them, I use cheap cotton sheet. Overlapping it onto the back adds strength and makes it look nice and neat.This lets the paint stick to the foam.

I like to undercoat each piece with masonry waterproof paint. Once the undercoat is dry it is time to paint away. Acrylic paint works great.

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2x2 Mounting Post

I used a keyhole cut out piece of 1/4" plywood on the back of the body to minimize the bolts showing through and so it would store compactly. The glue side of the pieces have clearance to let the bolt slip back out when disassembled.

Drill the 2" x 2" post for three keyhole mounts up the back. Alternate the bolt slots left-right-left so they will lock the 2" x 2" post in place. Bolt the plywood keyhole pieces together with the 2x2 so everything aligns and glue the keyhole blocks down with gorilla glue.

X Base

To keep it from flying away, a steel and wood base is attached to the bottom of the post and staked down with camping stakes.

The base is also collapseable. Pre-drill the 2x2 steel square tube for the 2'-8" length of 2x3 pine that is bolted to the base. Make sure there is clearance to tighten the 1/4" bolts after the steel angle is welded to the base.

Weld the 2'-8" angle iron to the square tube. You can braze it with a propane torch if you have no access to welding equipment.

Shim and stake to the ground so your bears do not become kites.

Cut out 4 3" circles of 1/8" plywood for each bear. Drill a 1/2" hole in the center of each.

Cut out 4 15" x 4" x 1/8" plywood in the shape above for the lever arms. The ropes are attached 4-4.5" from the pivot point depending on the clearance from the center post. Drill a 1/2" hole for the pivot point.

Sandwich the plywood circle on the front, foam arm, and plywood lever on the back and drill through with a 1/2" drill at the pivot point. Fill the hole with the 1/2" OD plastic spacers cut to be flush with the plywood. Glue the front and back plywood with Gorilla glue and use a 1/4" bolt and washers to let them dry with the holes aligned front and back.

Mount arms and legs after dry in the following order:

1. 1/4" carriage bolt
2. Plywood body
3. plain washer
4. nut - tighten
5. plain washer
6. arm/leg
7. plain washer
8. nyloc nut

A linear actuator with 8" travel was attached to the base of each bear. The actual speed of each bear is 30 seconds for a full loop but with 4 bears on separate actuators there is always something moving.

Look for a separate Instructable I am writing for building an actuator. Commercial units are available from Surplus Center or EBay but you need a timing circuit to stop and reverse the actuator plus a power supply.