When I was an undergraduate Physics major we would cook hot dogs by plugging them directly into a 120V outlet. This was a relatively hazardous operation as we simply attached the ends of an extension cord to two bolts, which were inserted into the hot dog. If you weren't careful and touched these bolts ("electrodes") while the cord was plugged in, I'm sure you can guess what would happen. Recently, after experimenting with a similar setup, I decided to build an electric hot dog cooker that would be much safer.
I wanted the key feature of this hot dog cooker to be an enclosed hot dog tray with a switch to ensure that current could only flow to the electrodes when the cover was closed. I also wanted to add a dimmer switch so that the current flowing through the hot dog could be varied. Previous experiments seemed to suggest that the hot dog was charing in the vicinity of the electrodes before the dog was fully cooked. As soon as the hot dog chars around the electrodes, conductivity between the hot dog and the electrodes decreases to the point where cooking cannot continue. By being able to decrease the current flowing through the hot dog, I hypothesized that cooking could be slowed and localized charing avoided. The final feature I wanted to add was a light that could indicate the level of current flowing through the hot dog.
Step 1: What I Used
I used the following supplies for this project:
Some scrap 3/4" thick and 3/8" thick pieces of wood
Short sections (< 1 ft) of 16 gauge wire
A blank electric box cover
A 600W rotary dimmer switch
A 120V, 3A, SPDT momentary push button switch
A 120V indicator lamp
An extension cord
Two #6 bolts with nuts and washers
A 1" PVC coupling
A 2" PVC coupling
2 small hinges and associated hardware
A handful of drywall screws and some other small wood screws
Some self-drilling screws
A 1/2" wide aluminum bar
A drawer pull handle
A 0.015" thick sheet of clear styrene
Step 2: Building the Clear Cover
The first step was to cut the 2" PVC coupling in half to form two shorter rings. One of these rings is then cut in half in the opposite direction to form two "U" shaped pieces.
The styrene sheet is scored to length and snapped. Styrene is cut by scoring a line and then bending along the score until it cracks. It's a little scary to do, but it has always broke cleanly for me.
Once the styrene is cut to length, it is attached to the two PVC "U" pieces with self-drilling screws. I used 4 screws set evenly around the arc of each piece.
Step 3: Adding Aluminum Bars to Cover
Two 1/2" wide aluminum bars are mounted to the cover to add rigidity and keep the styrene flat in between the "U" pieces. These bars are cut, drilled, and mounted to the PVC ends using the same self-drilling screws used to attach the styrene.
On the one side of the cover, the small hinges are attached over the aluminum bar with the screws holding them in place passing through the aluminum bar and into the PVC.
Step 4: Assembling the Base
A 3/4" thick piece of wood was cut to the correct width and length to accommodate the curved cover, and two 3/8" pieces of equal length were screwed to its sides to form the base of the system. Next the cover hinges were screwed to this base, completing the base assembly.
Step 5: Adding the Hot Dog Holders
I cut the 1" PVC coupling in half along its axis with the miter saw. I wasn't sure how this would work out, but it actually did a pretty nice job and was much quicker and neater than trying to use the hacksaw. These two halves were screwed down to the base with their centerlines being 4" apart. I had found that 4" was slightly shorter than the length of hot dogs I was cooking, which were pretty standard sized hot dogs. If you were cooking hot dogs of a different length (or sausages) you might want to adjust the spacing accordingly.
Once the PVC is mounted, I drilled holes through the center of each piece to accommodate the #6 screws, which will serve as the electrodes. These holes pass through both the holder and base. After drilling through the base, the base was flipped over and the bottom side of the holes were enlarged to accommodate the heads of the screws. I drilled about half way through the base with a 1/2" bit.
Step 6: Mounting the Switch
The last step to finish the base assembly was to add the momentary push button switch. I used a double pole momentary push button switch I had lying around, but you could use a single pole momentary push button - as long as it can handle at least 2 amps at 120V (~240W). I removed the back side of the base (the side with the hinges attached to it) and laid the switch on it under where the 2" PVC coupling sits. The goal is to have the PVC push the switch closed when the cover is down. I played with the height of the switch a bit until I was satisfied that it would be fully depressed when the cover was down without keeping the cover from fully closing.
After marking the outline of the switch, a recess was carved into the side of the base assembly using a rotary tool. I have a structured tooth carbine cutter that works well for removing large amounts of wood quickly. The switch was mounted into this recess using two small wood screws with washers. When test-fitting the side plate, it became apparent that a recess would also need to be cut in the side of the base bottom to accommodate the switch. After this was marked and cut, the side plate was re-attached to the bottom of the base.
Groves were also cut along the bottom of the base to allow the wires to the switch and electrodes to be recessed.
Step 7: The Electronics Box
Using pieces of 3/4" thick lumber, a small box was constructed to house the dimmer switch and keep all of the other electrical connections neat. I could have made this box neater, but I didn't have a lot of time so I threw it together quickly and just screwed everything together with drywall screws.
The box needs several holes drilled in it before it can be attached to the base. On the left side of the box (left when looking at the hole for the dimmer), two small holes were drilled for mounting to the base, with a large hole between them for passing wires through. I decided to mount the base 3/4" up from the bottom of the box. This would allow for screws to be easily passed through the side of the box and into the base. I also thought it would make the whole system look a bit more interesting. A second large hole was drilled in the back of the box to accommodate the power cord.
After drilling the holes, the box was disassembled and the left side was screwed to the end of the base using the mounting holes, which I had drilled. Once this side was attached to the base, the box was re-assembled, with the exception of the top.
Step 8: The Hole for the Light
A hole for the light needs to be drilled in the top of the box. After marking the center of the top, I drilled completely through it using a small drill bit (around 1/8"). From the bottom side, I drilled 3/4 of the way through the top with a large forstner bit. This hole needs to be large enough to allow the mounting nut of the light to be securely fastened. From the top side, a 5/8" forester bit was used to drill through and meet the larger hole. I would recommend drilling the 5/8" hole first to avoid chipping when the bit breaks through into the larger hole.
Step 9: Add the End Plate
The last bit of wood work was to add an end plate/support to the end of the base opposite the box. I simply used a 3/4" thick piece of wood cut to the width of the base with a height such that it would align with the top of the curved cover. This end plate was attached to the end of the base using two drywall screws.
With the wood work complete, the box, base, and end plate were sanded and spray painted black to make everything look neater.
Step 10: Wiring
Wiring for the hot dog cooker is quite simple. An extension cord with the female end cut off is used to supply power to the box. Current flows into the circuit along one of the wires in the cord and passes through the dimmer switch before flowing to the SPDT momentary push button switch. By connecting between the normally open (NO) and COM pins of the switch, current only flows through the switch when it is depressed. The circuit is completed through the hot dog, with the far end of the dog being connected back to the other wire of the extension cord. The light is connected in parallel with the hot dog.
Step 11: Connecting the Wiring
Four connections needed to be soldered - the wires connecting to the light and push button switch. All of the other connections were made with wire nuts inside of the box. Once everything was wired correctly, the dimmer was installed into the box. I drilled a hole in the blank electric box cover to allow it to slip over the post of the dimmer. For an extra cool factor, the dimmer knob was spray painted red.
Step 12: Install the Electrodes
The electrodes are made from 2" long #6 stainless steel screws. I tapered and smoothed the ends of the screws using a grindstone and the rotary tool. Wires were attached to the electrodes by wrapping the wire around the screw and tightening it between two washers placed between the screw head and a nut. Once the electrodes were wired, they were passed through the holes in the bottom of the base. Nuts were added on the top side of the base to keep the electrodes secure.
Step 13: Install the Handle
The final step is to add the drawer pull handle to the front on the cover. Two holes were carefully drilled in the aluminum bar for the mounting screws. One issue I had was that the mounting screws are made to be fastened through a thick piece of wood, making them too long for this application. To remedy this, I simply cut the screws to length using a cutoff disk.
Step 14: Testing the Hot Dog Cooker
Operation of the hot dog cooker is quite straightforward. A hot dog is placed onto the electrodes and the cover is closed. As long as the dimmer switch is turned on the hot dog will begin to cook. I found that cooking at full power tended to cook the hot dog too quickly and it would locally char, loose conductivity, and stop cooking before the dog was completely cooked. However, if I used the dimmer to reduced the current to somewhere around half-power, the cooking time was increased and the hot dog was cooked very well. In both cases, it was easy to tell when the hot dog was finished. You could audibly hear arcing between the electrodes and hot dog and the system would fill with smoke. If you continue to leave the hot dog on at this point, it will continue to arc around the electrodes, giving that part of the hot dog a burnt taste.
I was very pleased with how this hot dog cooker came out and was actually very impressed with how good of a hot dog it made! A fun little weekend project.