Make your very own steampunk piston out of a cigar box, clock parts, and spent bullet shells! Recycle your old clock parts to make a contraption that powers itself!
Step 1: Clock Guts
First off, find an old clock with easily accessible gears - cheap, busted clocks can usually be found at antique shops, clock shops and thrift stores. Carefully take it apart until you have it stripped down to just the mechanical housing (minus the pendulum, if it has one). Unscrew the housing and make sure to be careful that the spring steel doesn't unwind out of control - believe me, it hurts! I used tape to bind it so that it wouldn't feed out of the mechanism. Once you have the spring steel jammed, turn the gears around to see which gears move which gears. After a little time moving the gears around, you should be able to figure out which gear combination leads from ONE of the spring steel coils to the post (the longest gear where the hands of the clock face attach). For this particular clock, only 3 gears were involved - the spring steel unit itself, an intermediate gear, and the gear with the post (where the hands of the clock face attach). Remove all the extra gears and the second coil of steel. Once you have the proper gears isolated, screw the housing back together, making sure that the spring steel is still jammed.
Step 2: Cigar Box
Get your hands on a cigar box, which you can find for a good price in antique shops most of the time, or you can solicit a local humidor. Make sure that the box is big enough to hold the clock housing (with the spring wound fairly tight) and that it is deep enough for the clock to be completely covered so that only the post rises above the lid. Place the clock housing into the cigar box and carefully allow the spring steel to unwind, which it will try to do VERY quickly. Make sure the mechanism is braced in one corner of the cigar box. The spring steel will unwind and hold the mechanism in the box with spring tension. For added stability, you can screw the housing into the floor of the cigar box.
Step 3: Drilling
Close the lid of the box and see where the post hits the lid. Apply a little pressure to make an impression in the wood. To prevent the box from splintering, put masking tape on both sides of the lid where you will be drilling. Since the lid isn't going to line up exactly with the impression once it is closed, you will want to drill a little bit TOWARD the hinges from your mark. Use a drill bit that is larger than the post to give it a little room and prevent jamming, as well as helping the box to close. Drill from the inside and brace the lid over a flat piece of wood to prevent splintering. Repeat this step for the second post that comes out of the center of the spring steel - this post is square-shaped and turning it with the key will wind the steel, powering the contraption. The hole needs to be large enough to allow the key to be inserted.
Step 4: Bullet Shells
There are different shells which will fit inside one another fairly well. I found that brass Winchester 270's fit inside nickel-coated 416 Remington mags pretty well. Use a dremel tool with a cutoff disc to cut the tapered ends off of the shells so that you're left with just the shafts. Sand the ends flat and get rid of any sharp edges. I used an upholstry tack that was the same diameter as the open end of the 270 Winchester shell to use as a cap. Any flat or semi-domed brass or nickel cap will work as long as it matches the diameter of the shell.
Now for some soldering.
Step 5: Soldering
I would hope it goes without saying, but you can never be too careful, DO NOT UNDER ANY CIRCUMSTANCES TRY TO SOLDER UNFIRED CARTRIDGES - They contain GUN POWDER which will EXPLODE if heat or fire comes into contact with them. Only use spent shells, and make sure there is no gun powder residue on or inside of them.
This part can get kind of technical, but this is the method that I used:
Set up your soldering area: Solderite board, easy solder, brush on flux, an acetylene tank with an air intake attachment, and a third arm with tweezers or clamps.
For the piston, lay the 270 Winchester shell on it side and use tweezers to hold it steady, then position the upholstry tack so that the domed end is facing away from the rest of the shell. Slather some flux on it, lay down your solder chips and get to work with the torch. Use a solder pick to direct the solder around the seem to ensure complete closure. After that, turn the shell the other way and solder 2 washers to the end. Leave room between the washers and make sure they are symmetrical and equidistant with relation to the round lip of the shell (First Picture).
Set that aside and get the 416 shell. Carefully clamp the shell into a drill press without crushing it. Drill out the circular primer (the circular part in from the 416 REM MAG stamp) - this end will act as the intake. Take it to the solderite board. You can be pretty creative in how you make your exhaust chamber. For this exhaust, I took a second 270 shell and cut it down, saving the the two ends - about a 3/4 cm up from the rim at the primer end, and 3/4 cm down from the flare of the bullet end. I soldered the two pieces together to get the shape in the pictures below. Drill a hole into the side of the 416 shell that is roughtly (maybe slightly smaller) than the narrow end of the exhaust. File the narrow end of the exhaust, or use a dremel grinding attachment, to notch it to the approximate curvature of the 416 shell. Solder the exhaust to the 416 shell.
Use fine grain sandpaper to get rid of the fire scale and bring out the luster of the brass. The 416 shell is only nickel COATED, so you may sand it off accidentally.
Step 6: Determining Throw
In order for the piston to work properly, you need to determine 2 things: the length of the connecting rod and the diameter of the gear that it will attach to. These work together to determine the throw of the piston, or, how far the piston will move. This will take some guess work. The connecting rod I used was about 2 inches long and the gear was about 1 1/2 inches.
You don't necessarily have to use a gear, but any flat, rigid, round piece of copper, nickel or brass will work. Drill a hole in the center and, using the nut that holds the hands of the clock face to the post, solder it to the center of your gear/plate.
You might want to drill a couple of test holes in the plate (two can be seen in the first picture below) to see which will work best. Using 2 small nuts and bolts, connect the piston to the connecting rod, and the connecting rod to the gear/plate. Use washers to raise the connecting rod above the level of the nut you soldered to ensure clearance. Screw the gear/plate to the post coming out of the lid of the cigar box until it's tight. Hold the 416 shell chamber up and insert the piston. Here's where the guess work comes in: Use the key to wind the spring steel slightly, then move the 416 chamber around to find a spot where the piston steadily pumps back and forth with the least resistance. This will determine the best placement for the mounting bracket.
Step 7: Mounting Bracket
Once you have determined the position of the piston where it makes full revolutions with minimal resistance, you will want to mount it to the lid of the cigar box. I cut out a bracket from some sheet copper I had laying around and used a copper pipe end-cap to get a snug fit. Drill two small holes on the sides of where the piston will be to mount the bracket. Uses washers to prevent the box from splintering when tightening down the screws. A small sheath of leather wrapped around the 416 shell helps keep the piston in place and protects the shell from scratches.
Once the bracket is in place, assemble the piston and screw down the gear/plate to the post.
Step 8: Become the Envy of Your Friends With Your New Toy!
This is not a fully functioning piston because it doesn't have the valves in place. Valves could be added relatively easily (one intake valve and one exhaust valve). Greasing or lubricating the piston will also create a tighter air seal, further improving its efficiency.
Now just sit back and enjoy the mechanical hum!