Introduction: UDS Cold Smoker Electric Heating With PID Control
I wanted a cold smoker so that I could smoke cheese, nuts and make my own bacon, sausage, and smoked Thanksgiving turkey. I also did not want to spend my whole life tending the fire to maintain temperature. I investigate the commercial units and they did not have the room for a whole turkey or ham and several reviews said the electric models did not have a reliable smoking system, either an auger or special smoke briquettes . So I looked at a ugly drum smoker, but most were charcoal fired and required constant tending while operating. They also would not work for cheese or nuts and difficult to make bacon.
Using the internet I investigated reliable cold smoke units and found the Amaze-n smoking maze. It generates smoke for up to 12 hours on one fill of pellets and it does not raise the temperature above the melting point of the cheese. There are other units, but this is the one I chose.
Next I looked for a electric heating element and found a replacement element on Ebay, it was for a BBQ unit.
Then a heating control was need, there were several how-to articles on PID controls, one was ordered again from Ebay. I got a complete kit PID control, 40 amp relay and k type thermocouple. The unit I purchased was advertised as switchable Fahrenheit to Centigrade, but it only works Centigrade, so I added a thermometer to the unit that reads both so I use it to convert to Centigrade when I set the unit.
Finally I went to a local drum salvager and got an open top drum that had food products in it, NO CHEMICAL DRUMS.
Step 1: Layout, Door Cutting, and Hinge Installation
The drum was taken outside and the paint was burned off using a propane weed burner, another method would build a wood fire and set the drum on the fire to remove the paint. When the drum is cool use a wire brush and remove the ash. Then using masking tape layout where you want door. An abrasive cutting wheel on an angle grinder cut the door. Cut the hinge side of the door first. Then install the hinges on the door before finishing cutting out the door. The hinges will have to be bent slightly, this can be accomplished by grasping the hinge in a vise and striking the hinge barrel, raise the barrel up about an inch and tap the barrel again, repeat until the hinge has a arc matching the side of the drum. After the hinges are installed the other three sides of the door can be cut. Then remove the tape.
Step 2: Installing the Damper and Chimney
A damper and chimney are needed on the top of the smoker. Rather than make a damper I chose to purchase a waste gate from a woodworking dust collection system (metal not plastic). This was made for 5 inch pipe so all that was needed was to saw a hole in the center of the lid and install a pipe flange to the lid. the damper and chimney are just set in place without screws so the parts can be removed for storage and moving through doorways.
Step 3: Door Seal and Magnet Catch
A door seal was needed to cover the kerf (saw cut gap) around the doors. Galvanized steel flashing was purchased and cut into 4 inch wide strips that were 3 inches longer than the opening it was to cover. The flashing was then bend over to form a 2 inch wide piece. This piece was then marked 1 inch from the folded edge with a permanent marker. The marks were then lined up with the door opening so the flashing extended into the opening 1 inch (this was approximate since I did not cut the opening perfectly straight and square. The flashing was clamped in place to conform to the curve of the drum. Holes were drilled and the flashing was pop riveted to the drum.
Then magnets were placed in the corners to hold the door shut. A magnet from a damaged speaker and purchased magnets were used.
Step 4: Installing Racks on Adjustable Shelving Brackets
The inside diameter of the drum was measured and it was 23 plus inches in diameter. I found some BBQ replacement racks that were 22 inches in diameter 4 were purchased. I had 3- 36 inch long adjustable shelf bracket supports and clips. These were mounted inside the drum one on each side of the door and one in the center between the other two. A 2x4 was place of the bottom of the drum for spacing off the bottom (first I had located the strips from the top, but the lid would not fit so the strips were moved down). Washers were placed between the drum and the shelving strips so that the installed strips held the 22 inch racks with about a 1/4 inch of free space for moving and adjusting the racks.
One rack was placed below the door for a caught pan or water pan the others were spaced out for general use. If you get into making large quantities of small items additional racks can be purchased. For hanging items like sausage two rack can be stacked at the top and strings can be tied to the racks to suspend the sausages.
Step 5: Finishing
The outside of the drum was painted with heat resistant paint used on automobile exhaust manifolds.
A hole was drilled in the top for the thermocouple. The thermocouple was mounted in a pipe nipple with a brass cap for protection and this was attached to a pipe flange for ease of remove when in storage (the electronics are stored in the garage and the smoker unheated shed)/
The PID controller was wired and mounted to a panel.
A thermometer was installed in the door for verification of the temperature and to have a Fahrenheit to Centigrade conversion handy.
Handles were installed on the doors, one was taken off another BBQ and the other is a 1/4-20 bolt.
An opening was made in the bottom rear for the heating element cord.
The Amaze-n smoker was placed in the bottom of the drum.
Step 6: Building a Stand
A wooden stand was assembled from some scrap 2x2's, 1/2 inch plywood, 1x4's, and 4 purchased casters. The 1x4's were cut 24 inches long and assembled in a square with pocket screws. The 2x2 legs were cut 18" long and screwed to the 1x4 apron, flush on the top. Additional 2x2 were cut to span between the legs on the inside of the apron, again flush on top. These were also screwed to the apron. A piece of 1/2 inch plywood was cut 24-3/4 inch square. A 1x4 was ripped in 1/2 and cut to 24 inches long. These pieces were attached to the plywood flush with the outside of the plywood. The legs were then attached to the plywood apron. The whole assembly was turned upside down and the casters were attached 3/4 inch in from the outside of the plywood. A lag screw was used in the one caster hole that lined up with the leg. the other 3 holes had 1/4-20 bolts holding to the plywood. The stand was then sanded and painted.