Another mailbox mod

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M3 Pete

Newbie
Original poster
Oct 1, 2020
18
13
I know there are tons of mailbox mod threads, but I added a couple twists that I thought I'd share. Mine is going on the ground, so it needed a stand to give it enough clearance so the door would open without scraping the pavement. I had a scrap piece of 2x6, so I cut it long enough to use 4 of the attachment holes, while leave the other 4 attachment holes open for airflow. And I wanted to preclude any possibility of the wood catching fire, so I added a heat shield, which is probably unnecessary, but I had some scrap sheet metal hanging around so I figured why not?

If you do not have a 2x6, two pieces of 2x4 should work just as well, and maybe even better since you can place them flush against the sides for extra stability.

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I wanted to replace all the plastic hardware with metal, and I wanted it to "latch." So I created a "handle" out of an old bolt and a couple of nuts and washers. For the latch, I had a package of extra strong magnets left over from another project, and just put them inside the box, behind the rolled lip, which keeps the box closed.

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And here is the final product. Although the box and elbows are galvanized, with the AMNPS the box only gets warm (you can keep your hand on the top), and the connectors barely get above ambient temp. The top connector just press fits into the smoker. I only used one clamp (top connector), the bottom end of the hose just slides onto the elbow. I did tape the elbow onto the mailbox though. No leaks at all.

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I guess to make this a complete post I'll show the elbow attachment details.

Parts list:
Two 3-inch duct elbows (aluminum if you can find them, I just used galvanized)
One 3-inch x 8-foot semi-rigid duct
One Grayson Medium, Steel, Post Mount Mailbox (they sell aluminum ones, but they are 4x the price)
One (two is optional) 3-4 inch hose clamp
One 2x6 or two 2x4 (8.5 inches long)
Four 1-inch wood screws (broad head or small head with washer - I used GRK cabinet screws just because I had some, but any screw that is 3/4 to 2 inches will work)
Super magnets (optional)

First, cut a 3-inch hole in the end of the mailbox, about an inch from the top so you will have room for the flaps you are going to cut. I tried using a cheap Harbor Freight hole saw, but gave up after about five minutes and used tin snips.

On the elbow, mark a line 1 inch deep all around the non-crimped end. Starting right next to the overlap, mark and cut 16 cuts down to the line, fold half of the flaps out 90 degrees with pliers. Careful, these things are crazy sharp.

Insert the straight flaps into the 3-inch hole, and from inside, bend them down to secure the elbow to the mailbox. Seal with aluminum tape; I used high temp flue tape, but any aluminum tape will probably work.

Total cost: $28 (two 3-inch elbows: $8.48, one 3-inch semi-rigid duct: $9.42, mailbox: $9.89) all from Home Depot. Plus, of course, the AMNPS, which is about $30.

I already had the clamp ($1.75), the wood, the screws, magnets (cost: ?), and the flue tape ($9 at Amazon.com: 3M High Temperature Flue Tape, High Heat Sealing Tape up to 600 degrees, 15-Foot Roll: Home Improvement )

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Nicely done M3 Pete! Did you drill any holes in the side or bottom of the mailbox for air flow to help the AMPS stay lit?
 
Nicely done M3 Pete! Did you drill any holes in the side or bottom of the mailbox for air flow to help the AMPS stay lit?

Nope, the door does not really seal, so air gets in around it. But I did have a couple issues on my test burn yesterday. The AMNPS went out once when I closed the smoker vent halfway. I kept it open after that and it never went out again.

Then, when the smoldering pellets in the AMNPS got over the bottom hole on the right side, it flared up and started flaming. I could tell this before I even looked because suddenly the smoke increased and the smoke color looked "dirty." I had to spritz it with water to kill the flame, but the pellets kept smoldering to the end. I'm guessing that the airflow from that hole created enough of an airstream that caused the fire, like a bellows.

I will cover that right-side front hole next time, and leave one hole open in the door and see if that helps. I know that some guys raise the AMNPS a couple inches with bolts attached to the bottom, which may allow that air flow to diffuse before reaching the pellets. If it still needs more air, I can uncover the holes in the side for the mailbox flag, which I covered with tape. Or I could reposition the magnet(s) onto the edge of the door, so they keep it cracked open.

Total burn time for a full tray of Traeger blend and Kingsford cherry pellets was just about 8 hours
 
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And to anyone who wants about 4 days of good reading on this, here is a link to the 'old' mailbox thread on the MES forum. This really did change my smoking life. I'm at high altitude (Denver-ish) and I couldn't get consistent smoke to save my life. I did this mod and have never looked back. Ignore the makeshift chimney, that's a relic of the insane stuff I used to try to get consistent TBS.
 

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At high altitude (Denver-ish), I have had poor luck w/ the maze AMNPS. The tube AMNTS works pretty well. I have had better success w/ many air holes open, or even crack the door, until I'm *positive* it's lit well. Then I close off the holes to get something similar to Dave's picture. The 12" tube lasts a looong time in the mailbox, I remember over 8 hours once, always over 5 hours.
 
I know there are tons of mailbox mod threads, but I added a couple twists that I thought I'd share. Mine is going on the ground, so it needed a stand to give it enough clearance so the door would open without scraping the pavement. I had a scrap piece of 2x6, so I cut it long enough to use 4 of the attachment holes, while leave the other 4 attachment holes open for airflow. And I wanted to preclude any possibility of the wood catching fire, so I added a heat shield, which is probably unnecessary, but I had some scrap sheet metal hanging around so I figured why not?

If you do not have a 2x6, two pieces of 2x4 should work just as well, and maybe even better since you can place them flush against the sides for extra stability.

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Mines similar to yours. I sealed rear corners and mounting holes except the two pencil holes closest to the door and made a rack to elevate the Amnps and drilled a center hole between the two open holes so all air passes above and below the Amnps from the three holes and the door hinge. I rarely use more than two rows of pellets so I put a bolt in the hole infront of the 3rd row. The holes line up for the three rows in the Amnps so the lighting hole edge of the tray is at the holes but not over the holes. Bolt cutters and a tomato cage for a stand and a black shoelace with a spring stay to hold it on the stand. Made a coupling from 3"× 24" alum vent pipe.
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I normally just stick the coupling in the chip loader hole but can add the vent pipe for a longer run.
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A 4" ubolt I threw in the charcoal chimney to burn off the galvanized zinc coating works well on the round 12" tube smoker in the vent pipe mod. Slide it in out of the pipe to get the smoke you want without opening the smoker. Cylinder shot glass pellets rest against the bottom and a wire pin through the tube to hold jn place for custom sizing short smokes.
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I did the first actual smoke using the mailbox, for pulled pork with two boneless shoulders (Costco, about 7.5 pounds each). Got a solid 12 hours of smoke out of the AMNPS using Traeger Blend pellets, with the vent open all the way, even with a solid breeze. At 235 smoker temp that was enough to get me to the stall, so I wrapped them and didn't need any more smoke.

The shoulder on the lower shelf cooked faster than the upper, and was done a few hours before the upper shelf. In fact, I got tired of going outside in the dark and brought the last one into the oven at 275 to finish it off. Cooked both to 203 IT. Total cook time for the longer one was 17 hours (8 am to 1 am). Left them in a cooler till morning to pull, and they were still hot (first one was just below 140, second was still around 160).

Used SoFlaQer finishing sauce (1/2 cup for each) and the result was super juicy, and the meat super soft. Vacuum sealed and froze most of it. Made some cole slaw (mayo, apple cider vinegar, and a bit of BBQ sauce) and had some great sandwiches.

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I just realized that I never put the type of smoker I was modifying in the first post, and it's too late to edit. Just so people can find this in a search, the mailbox modification I made was for a Masterbuilt MES 30 (130B MB20071117) digital smoker. I am pretty sure that this mod works for all Masterbuilt electric smokers, and maybe other electric smokers as well.

I used an A-MAZE-N ANMPS maze pellet smoker, but you could use a pellet tube smoker or any self-burning smoke generator for pellets or dust that will fit in the mailbox.
 
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