My first build - 120 gallon tank

Discussion in 'Reverse Flow' started by joe ny, Mar 30, 2015.

  1. joe ny

    joe ny Fire Starter

    ok trying this again I lost the 1st post.  I have been reading this and other sites for the last year and am ready to start my project now.  I got a propane, I was told it was 120 gal, it is around 40"x30" wide.  I have very limited welding experience, just got a welder this year and have been practicing a bit.  Its a flux core/mig but I have no gas yet.  Is there a big difference between the 2, I will be welding outside and figured flux core would be the best way to go.

    I plan on making a reverse flow with 2 pull out shelves, maybe a removable exhaust stack with a possible cooking grate on the FB.

    I was trying to figure out what I will need and have used "Standard Reverse Flow Smoker Calculator... by DaveOmak" to crunch some of the numbers.  Here is what I have so far.

    CC: 27,720

    FB/CC opening 110.88

    under RF plate 110.88

    FB 9147

    Vents 27.72

    Exhaust Stack volume 471.24

    I have a bunch of questions and your opinions and experience are very welcome.

    What is the "under RF plate" should I make the RF plate the same height as the top of the FB opening in the CC?

    For the firebox does it make a difference if it is square or rectangle?  If rectangle should it be tall, wide or deep?  21" square is 9261 that enough for a tray and shelf?

    Regarding the fire box, it seems like a good idea to have the door go straight to the bottom for easy cleaning, does that cause other issues such as heat leaking out?

    The wheels of the cart should they be mounted under the firebox or just to the inside.  I was planning on using 1/4" for the FB and was concerned it would be too heavy on the FB side.  I was planning on using pneumatic tires just cause they look cool and I have seen ones rated at 300lbs each.  Is there a certain distance I should keep them from the FB?

    I was thinking of making a door in the top of the FB for grilling.  Would the FB need to be bigger, if using a gasket can I make a good seal?

    For the exhaust I can use 4" at about 37" long or 5" 24" long, does it make a difference?  If not I will see what I think looks cooler.

    Thanks again for any help given, pics to follow.  I know there will be a bunch more questions as I get working on this smoker.  This will be a long process hopefully be completed this year.

    Joe
     
  2. joe ny

    joe ny Fire Starter


    Here is a pic of the propane tank. It measures about 42" tall not counting the collar and 30" diameter. Thinking of making the first cuts this week.

    Joe
     
    Last edited: Apr 3, 2015
  3. joe ny

    joe ny Fire Starter

    Would it make a difference if I cut the FB from the bottom or the top of the tank?

    Thanks,
    Joe
     
    Last edited: Apr 3, 2015
  4. joe ny

    joe ny Fire Starter

    Not sure if I broke some forum etiquette I was not aware of.  I was looking for some advice before I start my project and after lurking here for the last year I have seen some great advice in many, many posts. I have learned a tremendous amount reading here but was looking for a few more pointers before I start cutting and hopefully avoid making a big mistake.

    Thanks,

    Joe
     
  5. The board seems awfully quite lately.  Hopefully the regulars are okay.  I was also surprised that i got no response to my q-view post.

    IMHO, once feet and collar are removed, it does not matter which end you cut for the FB.  Tank is the same standard throughout.

    Jerry
     
  6. lendecatural

    lendecatural Smoking Fanatic

    I'll take a stab at your initial questions, you didn't break any "rules", we just must have missed this one since it takes more time than the average request and got in the "to do" list and not followed back up.

    What is the "under RF plate" should I make the RF plate the same height as the top of the FB opening in the CC? Yes, that height at the FB/CC should be continued on as the RF plate inside the smoker. If you look at the end of the opening you cut to get the 110.8 sq-in, the RF plate will carry that area on down the inside of the CC.

    For the firebox does it make a difference if it is square or rectangle?  If rectangle should it be tall, wide or deep?  21" square is 9261 that enough for a tray and shelf? No, the firebox doesn't have to be square at all. You want the width to match up with the width of the RF plate so you don't have edges of firebox wider than the CC. Taller is generally better because it gives you a taller fire allowing room for the grate and area under for ash collection and better fire breathing. 

    Regarding the fire box, it seems like a good idea to have the door go straight to the bottom for easy cleaning, does that cause other issues such as heat leaking out? Yes, it would be easier, there are also a couple guys that incorporated a separate ash tray that is easily pulled out for cleaning. You do need it to seal so be careful which design you choose assuring you can get a good steel.

    The wheels of the cart should they be mounted under the firebox or just to the inside.  I was planning on using 1/4" for the FB and was concerned it would be too heavy on the FB side.  I was planning on using pneumatic tires just cause they look cool and I have seen ones rated at 300lbs each.  Is there a certain distance I should keep them from the FB? Yes, with the size of your smoker, you will likely have the firebox well above the axle depending on your wheel diameter and you will also need a decent wheelbase so it is stable. I would use a minimum of 10" and if they are getting hot, make a heat shield out of aluminum and attach it to the axle between the tire and the firebox.

    I was thinking of making a door in the top of the FB for grilling.  Would the FB need to be bigger, if using a gasket can I make a good seal? Yes, if you are going to add a grate to the top inside the firebox, you should allow a couple of extra inches of height to make up for the grate and you would need a very good seal since the hot air is trying hard to escape out the top when you need it to turn and go into the CC.

    For the exhaust I can use 4" at about 37" long or 5" 24" long, does it make a difference? Yes, the 4" would have more friction, you would be better off with a 5" at 30", it would provide the best draw with the least resistance. 

    Would it make a difference if I cut the FB from the bottom or the top of the tank? No, it won't matter, it is best to avoid any legacy fittings, so you should lay it out and double check you aren't cutting through anything thick that isn't necessary.

    Again, sorry we didn't get to you sooner and feel free to ask followup questions, we'll be along to help, some of us are a little old and slow. [​IMG]
     
  7. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    I have a bunch of questions and your opinions and experience are very welcome.



    What is the "under RF plate" should I make the RF plate the same height as the top of the FB opening in the CC? Yes...



    For the firebox does it make a difference if it is square or rectangle? If rectangle should it be tall, wide or deep? 21" square is 9261 that enough for a tray and shelf? Depends on the size of the firewood.... The FB can be larger than the numbers... Longer for long firewood... Taller to make room for more ash collection.... The numbers generated are a minimum and guideline...



    Regarding the fire box, it seems like a good idea to have the door go straight to the bottom for easy cleaning, does that cause other issues such as heat leaking out? Having a flange around the FB for the door to seal on, is a necessary item... A cleanout can be in the bottom of the FB and can also be used as an air inlet... Contemplate the operation of your new smoker before finalizing the design.... That will help... How you put in wood, how you clean out ash, where the doors should be.. etc...



    The wheels of the cart should they be mounted under the firebox or just to the inside. I was planning on using 1/4" for the FB and was concerned it would be too heavy on the FB side. I was planning on using pneumatic tires just cause they look cool and I have seen ones rated at 300lbs each. Is there a certain distance I should keep them from the FB? Some folks make steel "wagon" type wheels from pipe...



    I was thinking of making a door in the top of the FB for grilling. Would the FB need to be bigger, if using a gasket can I make a good seal?
    I would make a "stand alone" grill...



    For the exhaust I can use 4" at about 37" long or 5" 24" long, does it make a difference? If not I will see what I think looks cooler. I would go with a 5" x 30" above the CC... Then a choke plate on top of the stack ....



    Thanks again for any help given, pics to follow. I know there will be a bunch more questions as I get working on this smoker. This will be a long process hopefully be completed this year.



    Joe
     
  8. joe black

    joe black Master of the Pit OTBS Member

    Joe, welcome from another Joe, I personally think that you may have just hit the site when folks were taking a deep breath. I know from my experience that I will take it in spurts. Maybe I'm wrong and should be more consistent.

    As for your smoker, I think you got some good answers from Len. When Dave gets over his electrical experiment, I'm sure you will get a lot of valuable input from him. As far as I'm concerned, I'm not a builder and certainly don't want to give any bad advice. Out of all of your questions, the only thing that I could offer is that if your FB is not insulated, be careful about pneumatic tires.

    Otherwise, I'll be watching. Good luck, good building and good smoking, Joe
     
  9. Evening Joe I noticed you said you just purchased your first mig flux welder

    First to respond to your question if there is a big difference between flux and gas. I much prefer flux it is more forgiving in my opinion with that said I rarely use it because of the cost.

    You may be fine but the rest of this is just a general info post and wanted to make sure you read the manual which most of us don't.

    The biggest problem most first time mig welder users have is that the machine usually comes wired for gas and a small sample spool of flux wire to get you started. This is stupid on the manufacturers part.

    I think they should leave the lead wires off the connector blocks and put a sticker on it that says refer to manual for proper connection. Reason being is that most come wired for gas (DCEP) and you must have gas to properly run that polarity.

    They give you a sample spool of flux or most people buy some flux to try it out (planning to buy gas when they can afford it) flux needs to be wired (DCEN) If you try running DCEP with flux wire you will think either you have the worst welding skills in the world or your machine is a piece of crap. Both could be true, but if you correct the wire connections you will get decent welds with mig after just a few miles of welding Yes I said miles.

    If you don't know what DCEP and DCEN mean I suggest you read the manual.

    .

    I asked a friend who lays down weld like a robot if he could teach me to weld better he told me to hit the road when I get to L.A. turn around and head home after a couple thousand miles of welding it should look better.

    .

    "Welding tips and tricks" on you tube is a good place to get some advice.

    .

    Hope this helps someone

    Scott
     
    Last edited: Apr 9, 2015
  10. joe ny

    joe ny Fire Starter

    I would like to thank you all for the response from my questions.  I have had a week from hell at work and just rolled in the door, I plan on a few hours of sleep and do a little work on the smoker.  My son (9 years old) has taken a liking to working with me so I think this project might need a little more time for instruction and his "help".

    Len and Dave thanks for you insight, I am very apprehensive to make the first cuts but I gotta start somewhere and feel better that I am on the right track.

    As far as the door on the top of the FB for a grill I think that will not be included, for the added difficulty and possibility of heat leakage.

    Joe, I am concerned about the pneumatic tires but I think they look cool, I'll have to see how they work out with the heat from the FB.

    Scott, thanks for the welder/welding tips.  I have spent many hours pouring over videos, some good some not so, welding tips and tricks has been some of my favorites.  I have seen about a dozen of them.  You mentioned you don't use flux core because of the cost.  Is that because the wire is much more expensive and can I assume that the cost of mig wire + gas is cheaper than the flux core.  I guess I am shying from the initial purchase of the bottle.

    I know you guys all love pics, heck I can't get enough when I follow a build, more to come as I get some work done.

    Joe

    PS, is there a going rate for steel, $x per lb or something?  I am getting very different prices and they all seem a bit much, I know the price of metal is going up but I wonder if they see a newbie welder and jack up the price.
     
  11. Steel prices are going to vary I think it depends where you go. I would say defiantly don't go to lowes or Home Depot or a place that has a small selection of steel. They typically are a huge rip off for steel. My company does a lot of structural steel work so we buy a lot. I got a price from two of our suppliers for a 4x8 sheet of 1/4 smooth plate. One was 148.00 one was 166.00. I don't know how much a sheet of 1/4 plate weighs. And the I came across a add on Craigslist of a local metal yard selling steel mostly cut offs and extras I assume for .30 a lb. so that is an idea I guess. But I don't think you will be getting new full length steel at .30 a lb. do a search for metal suppliers in your area. Good luck.

    Add: I just did the math on the weight and price of a sheet of 1/4 plate my lowest price came out to around 45 cents per pound.
     
    Last edited: Apr 12, 2015
  12. lendecatural

    lendecatural Smoking Fanatic

    Prices are supply and demand and do vary a lot. If you know anyone in the fabrication business, see if you can tag on one of their orders, they get really good prices. One of my friends has a big fab shop and I get to run my stuff through his account number but pay cash at pickup. He buys by the truckload and gets awesome pricing structure. I've only bought stainless so my data wouldn't help. I also actively cruise the recycle yards. They pay pennies on the pound and sell cheap but you must stop by regularly to keep up with their stock. I got 30' of 2x2 stainless tubing for 20% of new price and it had a couple of nicks in it, I don't care about that so it was a great deal for me.
     
  13. Joe,

    For what it's worth: I first used Northern Tool 10" flat free tires.  Too much weight for them.  Then returned them for the 12" flat free.  The 12" develop flat spots quickly.  Not suited to constant weight.  Returned them for 12" x 3" solid rubber wheels.  HUGE difference.  Can move the smokier around with ease.  Heat was not an issue on any of them.

    Jerry

     
    tykenn28 likes this.
  14. joe ny

    joe ny Fire Starter

    Got a quote for a 4x8 plate 1/4" for $400.  Little to rich for my blood.
     
  15. joe ny

    joe ny Fire Starter

    Thanks for the info Jerry.  I watched your build with great care, nice build and I have learned from yours and others.
     
    Last edited: Apr 12, 2015
  16. Wow!
     
  17. joe ny

    joe ny Fire Starter

    Got a some progress today and made the first cuts, measured out the FB and cut it out and started measuring the door.  I have my son helping so it is slow going but worth every second.  He is getting psyched helping me, it is great spending the time and hopefully pass on some knowledge.  Not only did he help measure and mark the tank he also took the pics. 

    Tomorrow I will be cutting the CC door and Saturday welding the flange and the hinges to the door and completing the cut.  Hopefully all will be square and no springing.  Thanks Dave for your tutorial it has been instrumental for the build.


    Cutting off the collar.  Note to self wear a hat your getting really bald.


    Measured like 10 times



    Loving the angle grinder, it made quick work of the tank


    Little help from my hammer and...


    Viola open and my little girl posing.


    Measuring for the CC door
     
    Last edited: Apr 13, 2015
  18. rotor head

    rotor head Fire Starter

    Good luck on your build Joe from one more Joe you'll have a great time and will be happy every night to see its progress. I am also doing my first build its the one under Roter Head.
     
  19. joe ny

    joe ny Fire Starter

    Thanks Joe, will keep an eye out maybe we can learn together and avoid some pitfalls.

    Joe
     
  20. rotor head

    rotor head Fire Starter

    yeah I already had one. didn't position wheels in right place and it started to tip over on the firebox end. I got a good laugh out of it now I have to fix just think I will fill the other other legs with lead. on your question on the flux core its going to be a personal thing I like gas better no slag to clean. 
     

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