Thursday, October 17, 2013

How to Build a Mini WSM Smoker

The mini WSM is named after the Weber Smoky Mountain smoker. The WSM smoker is a very popular vertical charcoal smoker, priced at about $200. It comes in two sizes: 18.5 inch and 22 inch.
You can build a mini WSM by using a small Weber kettle grill (Smokey Joe), a 32 qt tamale steamer pot, and some assorted hardware. Be sure to check Craiglist for a used Smokey Joe, I've seen them listed there for as little as $10.

The pot I used is a 32 qt tamale steamer pot made by Vasconia, and sold by Phaltzgraff. There are other brands that will work, but I bought the Vasconia because it was known to be a good fit. If you're willing to shop around you can probably find something cheaper that works. Just make sure the pot sits snugly in the Smokey Joe so you won't have any air leaks.

There are two different models of the Smokey Joe grill - Silver and Gold. The main difference between them is the air inlet. The silver has a sliding air inlet on the bottom, the Gold has four 3/4 inch holes on the side. For smoking, many pitmasters prefer the Gold. During a long smoking session, ash can clog up the bottom vents on the Silver, and choke out your fire. I used the gold as well, as the size of the side air vents was perfect to pair with my BBQ Guru stoker.

I also built a charcoal basket for my smoker. (above) This keeps the charcoal close together, allowing ash to fall to the bottom. The bottom of the basket is the Smokey Joe charcoal grate, and the sides are made with 3 inch strips of expanded steel. Expanded steel is available from any of the big box home improvement store. I bought a 12 inch x 24 inch sheet and cut two strips 3 inches high. The sides are secured to the charcoal grate using stainless steel wire.

It is very import to never use galvanized metal of any kind to build a smoker. The galvanized metal will burn off nasty chemicals that can make you sick.

On the sides of the pot you'll need to drill three 1/4" holes for your grill rack. You can see one of them in the picture above, at the top. Through the hole is a 1/4 inch x 3/4 inch stainless steel hex bolt, a nut, two 1/4" steel washers, and an acorn nut on the outside. The 3 holes should be spaced approximately 14.5 inches around the outside of the pot. Below my grill rack bolt, you can see I've installed two 1/4" grommets. These holes will be used for my temperature probes.

Here's the rack inside the steamer pot, with the temperature probes through the grommets.

The next step is to either cut out the bottom out of your steamer pot, or to drill it with holes to allow the heat and smoke to get to your food.

I decided to cut the bottom out of the pot, leaving a little bit of a lip around the edge. Other mini builders I talked to said they thought it burned better without the bottom, and allowed more room for charcoal. The easiest way to cut the bottom is using a jigsaw equipped with a metal cutting blade.
You don't want to cut the entire bottom out, or your pot will become too flimsy. Leave at least a 1/2 inch lip.

To assemble your mini, put the charcoal basket in the bottom of the Smokey Joe and place your steamer pot on top. You can then add the tamale steamer insert as a diffuser (optional), then place your grill grate on top of the bolts, and the Smokey Joe lid on top.

These are two of the holes on the side of the Smokey Joe Gold. The one on the left I plugged up with a 3/4 inch black iron plug. The one on the right has the 3/4 inch BBQ guru adapter, with a 4 cfm stoker fan. This will attach to my BBQ guru DigiQ.

To start the fire, I put some charcoal in the basket, leaving a space in the middle. Then I started a few pieces of charcoal in the chimney starter. When these coals are fully ashed over, I drop those in the space in the middle of the basket. If you're using wood chunks for smoke flavor, intersperse those with your charcoal. This was just a test run, so I left those out.
I coated the inside of the steamer pot with a little bit of oil, so it could season. The pot is aluminum so this just helps seal everything up.

 With everything in place, I set the BBQ Guru for 225 degrees and let it go for 2 hours.

For my first smoke in the mini I decided to reverse sear a tri tip. I took the pot off the Smokey Joe briefly to toss in a chunk of cherry wood for smoke flavor, then put my spice rubbed tri tip on the grill. There is a temperature probe in the meat so I can monitor the internal temperature.
It took about 50 minutes reach 125 degrees internal temp. Then I removed the tri tip from the smoker, removed the steamer pot from the grill, and placed the grill grate on the Smokey Joe right above the coals. I waited a few minutes for the fire to stoke up and get very hot, then placed the tri tip on to sear.
About a minute a side should be all that's needed. By now your internal temp should be up to about 130 for a nice medium rare.

If you like, you can paint the steamer pot with high temperature paint. I used a stencil to trace these pictures and then used the stencil to cut out painters tape. (several strips of tape, slightly overlapping) I used Rustoleum high heat paint, but if you go to an auto parts store, you can find one that's more glossy and will match the Smokey Joe better.
All in all this was a really fun project and costs less than $100. The initial build took about two hours once I had all the parts. And the smoker itself works great!