Key Mechanism - Wind Up Doll

I decided I wanted to create a Steampunk wind up doll costume this year. Here is how I made a wearable working key mechanism.

3/4" Baltic Birch Plywood - approx 10" x 10"

1/4" Baltic Birch approx 8" x 5"

1/8" Baltic Birch - approx 10" x 10"

0.20" polycarbonite

Bronze metallic paint

Battery holder - 4 x AA

4 x AA batteries

electric motor 6V - 15RPM - very slow

2 Plastic gear kits

6" Central vac pipe - 2" diameter

4 - Button head bolts 1/4-20 x 2" long

4 - 1/4-20 threaded inserts

10 - #6 x 1/2" wood screws

12' 18 guage wire - 6' red, 6' black

rocker switch

leather

cord

1/8" dowel

3/8" wire loom

clear wood finish

wood glue

4 - D-rings

1 - child seat restraint

small piece of 3/8" tubing

small hose clamp

With all ofthe parts purchased, I could determine the space that was needed to assemble and install all of the parts. I wanted the overall design to look like a large thick gear. I deceided birch plywood would be easiest solution the cut the pieces and I vary the thickness of the layers if I needed to. I was able to make three 3/4" pieces work. The top section to hold the gears and fasten the motor to. the centre one just as a spacer and the last for addtional space and the attach a recessed bottom. I cut all piieces using a cnc router using a 6mm and 3mm compression spiral bit. I machined a pocket for the motor to press fit into for more stability.

The bottom piece has hole drilled on the one side to accept the threade inserts. Bue sure to apply glue. The layers themselves are not glued just in case something has to replaced and sizes of the new parts may differ. The bolts hold eveything together.

Apply 3 coats of clear finish to the area where the gears will be installed.Sand in between each coat with very fine sandpaper. You want this area super smooth to reduce gear friction.

Making the key consists of 3 plywood components and a 6 inch piece of PVC central vac pipe. I selected this type of pipe because it was light weight and easy to glue to the ply wood. A 3/4" piece of plywood is cut to match the inside diameter of the PVC pipe and glued flush in place. The top plug consists of a 3/4" and 1/4" pieces glued together to form a piece 1" thick using wood glue.

The 3D top plug was machined double sided using a CNC router. The top of the plug is notched to receive the bottom of the key. Once glued in,it forms a sold base to attach it to the pipe.

Take all of pieces and glue them together. Fasten a medium sized gear to the bottom of the key, it will be used to make the other gears move. Paint the entire thing with the bronze metallic paint.

To help me with this portion of the build I made a second key shaft with a gear attached at the bottom to help figure out the gear layout. There is no right or wrong way. You want to ensure all gear turn, all move easily and you have no gear touching more than one gear at once. It may be alright with the motor you choose but I found it created too much friction. Attach each gear using a #6 screw and tighten to the point where the gear can still spin freely. Once all the gears are in place you should test that they all spin. Fasten the motor into position and attach a medium sized gear onto the motor shaft. Attach the power to the motor and see if all of the gears are moving. You may have to make a few adjustments if they are not.

You can now make and attch the polycarbonite lens that covers the gears. I used double-side tape to attach it.

Once you have all of that working, you will want to test the key for spin. Attach the key and gear to the shaft of the motor and see if it spins with the unit laying flat, then in the postion you will wear it.

Attac

I have seen where other people have used battery operated dico ball motors. It could work in this case but would have to be taken apart and modified. The motor I used was from the surplus store and was about two dollars.

The watch portion will take a litttle more attention. After machining the main body, I chose to cut off the arms off of the one side. I liked the look better. the other arms need a 1/8" diameter hole drilled in so a piece of dowel could be added. This will be used to help secure the wiring for the switch and to attach the leather cover. A hole will also need to be drilled betwwen the two remaining arms for the wiring to fit through.

Glue the lens to the body using wood glue and glue the switch in with hot glue. Solder the two wires to switch and feed the remaining wire through the hole where it will be covered with the loom and the leather. You can use a leather punch or awl to make the holes in the leather after folding it in half. make a slit in the fold for the wires to fit through.When eveything is in place, use the cord to stitch it up and secure everything.

The other end of the wires and loom will be fed into a hole drilled in the base of the gear control box.

The wiring is pretty straight forward. Start with the red wire from the battery holder and connect it to the red wire coming from the switch. Connect the black wire from the switch to the black wire on the motor. Connect the remaining wires on the motor and the battery holder. flip the switch and make sure everything is working. I opted to solder all of the connections and sealed them with shrink tube but there are other solderless options. Choose what works best for you. Secure any loose components and screw the back on.

Iadded a small piece of tubing which I glued into the hole in the control box to make attaching the wire loom easier and connected both using a small hose clamp.

Position the D-Rings so the harness will easily go over each shoulder and one on each side so the side staps can be clipped at the front. Adjust the straps so the control box fit snugly but confortably. You are now good to go!

Here is what I used for the harness.

https://www.amazon.ca/Adjustable-Stroller-Safety-Dining-Harness/dp/B07V6B4741/ref=sr_1_1_sspa?crid=19EBNKWHSSBU8&keywords=child+seat+harness+black&qid=1666318735&qu=eyJxc2MiOiIxLjQ2IiwicXNhIjoiMC4wMCIsInFzcCI6IjAuMDAifQ%3D%3D&sprefix=child+seat+harness+blac%2Caps%2C158&sr=8-1-spons&psc=1