Rear Fire Box for Propane Smoker - No more opening the door! - AMNPS Ready!

Discussion in 'Propane Smokers' started by s2k9k, May 30, 2012.

  1. s2k9k

    s2k9k AMNPS Test Group

    I finally finished my RFB (rear fire box) for my GOSM (Great Outdoors Smokey Mountain) propane smoker. Awhile back I posted some pictures of a prototype I was working on and I have finished it. This all came about because I want to be able to use an AMNPS during hot smokes so I don't have to keep opening the door and adding wood. Wood chunks only last about 45 minutes in the chip pan so I am constantly opening the door and letting heat out so I thought the AMNPS would solve this problem but after much research I learned the AMNPS doesn't really work very good inside of propane smokers during hot smokes. I got a lot of great advice from "forluvofsmoke", "NWDave" and "TJohnson" and one of them (I forget now) added a CharGriller side fire box to their GOSM to use the AMNPS, so I thought "that must be the way to go". Well being I'm cheap and always like to find an inexpensive way out I started looking for alternatives to the $60 CG SFB. I read about using a mailbox and then thought of a metal toolbox because I like the way the top opened. I found one at my Dads house he didn't want so I went to work.

    I decided to mount it on the back because the side wasn't wide enough. I wanted to make it able to be taken off in case I didn't want to use it or needed to move the smoker, so I found some old drawer slides in my garage and mounted them on the bottom and also cut a hole in the back for the transfer pipe:



    I made a transfer pipe out of a piece of sheet metal and after cutting a hole in the toolbox mounted it to the back of the box and sealed it with some high temp RTV, I didn't get a picture but I also cut a hole in the end of the toolbox and used a piece of sheet metal as a damper: 


    During my prototype I had a lot of smoke leakage so I sealed everything up real good on this one. I put high temp rope gasket around the edge of the lid of the toolbox:


    And also used it around the hole where the transfer pipe enters the back of the smoker:


    Now all I have to do is slide out the supports and guide the transfer pipe into the smoker and it is ready to go:


    And inside view:


    I smoked some ribs this weekend and used my chip pan inside the RFB and it worked great. I put 4 pieces of charcoal in the pan and lit them with a propane torch then set 2 chunks of hickory on top and shut the lid. It produced a real nice TBS out the top vent of the smoker for 2 hours, those same 2 chunks in the pan inside of the smoker would have only lasted about 45 minutes. When the TBS went away all I had to open was the RFB and stoke up the wood a bit and I added another chunk and it kept going. I played around to see and I was able to control the amount of smoke adjusting the damper on the side controlling how much fresh air was going into it. I was able to go the first 3 hours of my 3-2-1 ribs without ever opening the door to the smoker and still keep smoke going the whole time. 

    I feel this was a success and I have less than $20 in it. I do not have an AMNPS yet but I am confident that it will work and that I will be able to get 8-10 hours of smoke without having to touch anything except maybe the damper.

    Now my dilemma, I hear Todd is working on something new, so do I go ahead and buy an AMNPS or wait and see what he is working on? Hmmmmmmm

    Thanks for looking!
    Last edited: Jul 26, 2012
  2. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Dave, morning....  what a great mod..... good design and sounds like it works very well....   I'm not sure what the design is on Todd's new smoke gen....  I know what the AMNPS does and seeing your mod work, and the increased length of time  you get out of the chunks, and how happy you are with the mod, I would be confident in purchasing the AMNPS and using it....

    I am really impressed with the AMNPS... It is better than all the rave reviews have pictured it....   Dave 
  3. Great ingenuity! 
  4. scarbelly

    scarbelly Smoking Guru OTBS Member

    Great job Dave - that is an awesome mod. I think the AMNPS is still going to be your best bet based on this mod. Todd new toy is designed to go inside a smoker if I remember correctly. 
  5. nwdave

    nwdave Master of the Pit SMF Premier Member

    Ding, Ding, Ding.......we have a winner here.  [​IMG]When I added the Char Grill Fire Box, weight was the most difficult part of the construction and of course, its a permanent installation, or at least time consuming to restore the GOSM back to factory condition (saved the side vent louver's).  So what do you cover the hole in the back of the GOSM with when the Tool Box Smoker adaptation is removed (I really like the built in carry handle on the tool box, sure is going to be handy carrying the smoke box).  I'd think something like a  square piece of metal, about an inch overlap on all sides.  One screw in an upper corner to act as a pivot and a slot in the opposing corner for a screw which is mounted in the GOSM.  The plate pivots up out of the way when the smoke box is installed.  When the smoke box is removed, the plate pivots down to cover the hole, slot slides under and aligns with screw, screw down and you're good to go.  Of course you've come up with that solution already.  I just can't help myself pondering an answer.

    Outstanding solution.  [​IMG]I hate to tell you but now you're cursed with the "I see a better way to improve on something" curse.  It's not a bad place to be.

  6. s2k9k

    s2k9k AMNPS Test Group

    Thanks a lot Dave!!! Yea I've had that curse all my life, I've always taken things apart and rebuilt things to my liking. 

    Though I haven't installed it yet, you are exactly right on the door to cover the hole. I did the same thing on the side of the FB for a damper.
  7. forluvofsmoke

    forluvofsmoke Smoking Guru OTBS Member

    Too many going by the name of Dave on this thread (LOL!!!) so I'll address you by your screen name, S2K9K.

    That's SWEET!!! You could literally throw anything into that smoke box to generate smoke. It sure will solve any problems with fitting a smoke generator into the bottom of the narrower GOSM cabinet, shielding from heat and drippings, etc, and as you mentioned, no more opening the cabinet door. You nailed down the whole concept very nicely!

    You will enjoy using the AMNPS...I promise! With adequate air flow to keep the pellets smoldering (doesn't need much, either), it works like a dream.

    I'm also not one for buying something to make mods if I don't absolutely need to. There always seems to be a way to get from point A to point B with salvaged materials...may take a bit more work and engineering to pull it off sometimes, but you can usually take advantage of any preformed/prefabbed items and come up  with a solution.

    I thought about putting my old SnP SFB onto my GOSM 3405-GW about a year ago...never got around to it, as the 18" dia SFB was too much for a side mount, and I didn't want to go with a rear mount...that thing is just way too big and heavy, and would need additional support legs.

    Well done, brother!

  8. s2k9k

    s2k9k AMNPS Test Group

    Thanks guys! I really appreciate it but I couldn't have done it without you! You all gave me the ideas and all the information I needed to be able to accomplish a working unit. I remembered earlier who had the mailbox...Pops! on the side of his smokehouse! Thanks to you too Pops! I love SMF, we might be many miles apart but we can still put our heads together to come up with some really good stuff!

    Thanks again!
  9. nwdave

    nwdave Master of the Pit SMF Premier Member

    Now, have you thought about putting a glass door in the front of the GOSM?  Puts an end to peeking to see how it's going.  Been there, done that, got the glass door now.
  10. s2k9k

    s2k9k AMNPS Test Group

    Yea I saw yours, that's nice but don't tempt me I have a piece of tempered from an old stereo cabinet.

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