Tuesday, January 25, 2011

Building a cold smoker, Part 1 -- Construction of the Parts

This is Part 1 of a jointly-authored post by Aryeh and Eli.
I’ve [Eli] been thinking about building a cold smoker for a while.  A cold smoker is a food preparation device to smoke foods at low (<90F) temperatures. This process is used in making lox, bacon, and lots of other foods. The basic principle is that you have a “hot box” where you generate the smoke, and a “cold box” where you place the food. You then connect the two together with ducting so the smoke has time to cool off.

Recently my [Eli’s] lab purchased a really expensive piece of scientific equipment which came in nice wooden crates. I decided these crates would be perfect boxes making the smoker.  Aryeh came over for the weekend, so we built the smoker together. The first thing we needed to do was modify the crate to make it into the “cold box”.

The crate originally had a screw-on lid, which we wanted to convert to a door, and we wanted to seal off the door so smoke wouldn’t escape to quickly.  For that, we used a strip of nail-on nylon weather stripping, which we nailed around the edge of the lid.
And, to make it into a door, we attached hinges.  Unfortunately, we forget to check the region under the hinges, so we drilled out holes for the protruding screws.

To complete the door we attached two latches to the other side of the door to hold it closed.

We had a 4” ducting “take-off” to connect the flexible ducting to the inlet of the cold side of the smoker.  However, we did not have a  4” hole saw.  In fact we had no hole saws or jig saws at all (as a side note, this sounds like the start of a Doctor Sues book).  So we decided that we where going to drill lots of little holes and then punch out the middle section.  We marked the center point of the hole, and then using some paracord  that I [Aryeh] had on me (yes, I do carry a length of paracord with me, its amazing stuff that I [Aryeh] will post about at a future date) we created a simple compass and marked a circle with a diameter of 4”.

We then drilled lots of holes.
However the wood was ⅜” thick and would not punch out easily.  So we drilled holes farther into the circle but in-between the outside holes.

This allowed us to get the hole.  However, we where still far from done.  The hole was very imprecise and we needed to clean the edges up.  This was accomplished with a smaller drill bit, an ancient hand saw and a grind wheel for the drill.  This was a huge pain in the neck, and we should’ve just bought the stinkin’ hole saw!

We wrapped this up with a little U-bolt and S-hook to hang food from, and the cold box was complete!

For the hot box, we modified a version of Alton Brown’s cardboard smoker.  The major difference with our box was that we needed to get the smoke out of the box, and into the larger crate.  Another 4” takeoff would allow us to attach the duct, but we still needed to get the smoke out.

To accomplish this, we attached a little DC fan, much like those found inside computers, on the outside of the box with two bolts. The fan was oriented to force [cold!] outside air into the box, creating positive pressure, cooling and forcing the smoke out of the hot box and down the duct. We connected the fan to a dying 9V battery (fan is rated for 5V, hence the dying battery) taped to the side of the box.

We then cut a little door to have access to the burner and made a nifty handle out of a bolt and two nuts.

Stay tuned for Thursday, where we show how to put it all together and make some lovely smoke!

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