Hexagonal smoker.

[bbq city]

Hello everyone,

I'm new to this forum and find it very entertaining and useful to read all your previous builds.

Where i'm from there is a real shortage on propane or oil tanks so i want to build my smoker out of 1/4" steel plate.

please check out the plans i made so far measurements will be 

25" by 22" hexagon 59" long cooking chamber and a 25" by 25" by 22" firebox. I'm having a bit of trouble with the calculator as far as the chimney is concerned (dimension wise) 

I'm planning on a reverse flow smoker. also want to make the subframe exchangeable so later on i can make a trailer to take the smoker to wherever we want to go.

Also a question about the baffelplate(?) to create a reverse flow...... will it not take a lot of the heat away?

Well, I will be posting about my plans and the progress of the build to follow regularly so you can enjoy the process with me.

Please feel free to comment in whatever way shape or form...... I'm open for suggestions!

until next post!

Marcel

Smoker dwg 3.jpg

• bbq city
• Feb 22, 2013

 

[vtmecheng]

If you are worried about heat loss going with extra thick steal plate will not help much.  Steel is a bad insulator.  If you really want it to hold the heat in do some searching on here for double walled smoker builds.  The idea is to have an inner wall and outer wall, separated by an air gap.  Some place insulation in this air gap but to be honest the insulation is unnecessary.   The whole point of insulation is to hold air in place, against the area you want to keep heat or cold within.  It isn't the material itself that does most of the insulating, it's the air trapped within the insulation.  That is why the insulation in your house attic should be fluffy instead of packed down.  For your smoker, if the inner and outer walls are sealed off from the outside air either with welds or a sealant than that trapped air will provide all the insulation you need.  The gap between inner and outer walls will dictate the rate of heat rejection from inside your smoker to the outside.

Regarding the reverse flow baffle, if the smoker is well insulated all around all it will do is help distribute the heat throughout your smoker.  Yes the area below the baffle will be at a slightly higher temperature than the area above it but we are talking only a little bit, this again because steel is a bad insulator.  What the baffle will do is force the air to to flow throughout your smoker so temps are more constant in the cooking area.

Happy building, I am jealous of anyone with the means, space, and tools to build a custom smoker like this.  I have the knowledge but no welder, garage, money, or time to do it. Ah well, guess that's why I am on here dreaming about it.

 

[Dutch]

Interesting design Marcel.  I'm sure that the members that have done build will chime in with their 2¢. From looking at you side view (bottom row) is the top shaped like a wide V?  If so I think you would be better off just going with a flat top. If the top comes to a peak ^ you will end up with dead space that you'll waste fuel on to heat up.

Also a question about the baffelplate(?) to create a reverse flow...... will it not take a lot of the heat away?

The baffle plate will absorb heat as the heat and smoke passes underneath; once the plate gets hot, it will radiate heat up into the underside of the meat-this is also known as convection heat transfer. Also, the heat in the plate will speed up your recovery times. I find that in my Lang I can cook an 8 lb butt in about 10 hours whereas in my propane smoker it will take between 12-14 hours.  So in answer to your question, the answer would be No, because the heat is being transfered in a different manner (convection).

 

[bbq city]

@ VTMechEng

one day you can make dreams come true! the path to realizing your dreams is the exciting part anyway,,,,,,,,

Thanks for your comments.

@ Dutch

I think I need the V shaped top because I want to be able to put bigger chunks of meat on the top grate..... 

you wrote: "I'm sure that the members that have done build will chime in with their 2¢.".......

[color= rgb(24, 24, 24)]  What do you mean by 2c?[/color]

[color= rgb(24, 24, 24)]thanks for your comments I will take them into concideration you've got some solid remarks there.....[/color]

 

[zimmbillie]

Can't wait to see some progress pics 

 

[pwillie]

According to Lang, who builds fine reverse flow smokers in Georgia, the top should never be flat because steele will sweat and the condensation that collects on the top should be able to roll down the sides and not drip into the smoker.  That is why his smokers have a curved top.  I suppose that a top that is v'ed will serve a similar purpose.  I am not a knowledgable builder so that is just my comment and two cents worth from what I have read.

 

[bbq city]

@ zimmbillie I can't  wait either

.... first have to get me som metal...... and then we'll see!

will be (have to) finish before summer!

 

[hambone1950]

@ VTMechEng
you wrote: "I'm sure that the members that have done build will chime in with their 2¢.".......

 What do you mean by 2c?

He means their two cents worth :grilling_smilie:

 

[bbq city]

I allready understood it would be something like that.... thaks anyway!

 

[rasimmo]

I ran your numbers through the calculator. I assumed the cook chamber will be 22" tall and 25" deep. The total volume comes out to be 24337.5 cu in. At that volume the recommened firebox is 8112.5 cu in. What you are planning is 13750 cu in or 169.5% of what you need. Too big is not a bad thing, but I would probably cut it down some. If you use a 6" pipe for the stack it needs to be 24.33" tall. I am not sure if that was your question or not about the stack. 41.25 sq in of air intake and 110 sq in firebox to cook chamber opening.

I could not get it to copy and paste the link like it is supposed to so I had to just type it out. I like the plans and think it will make a nice looking smoker.

 

[vtmecheng]

I ran your numbers through the calculator. I assumed the cook chamber will be 22" tall and 25" deep. The total volume comes out to be 24337.5 cu in. At that volume the recommened firebox is 8112.5 cu in. What you are planning is 13750 cu in or 169.5% of what you need. Too big is not a bad thing, but I would probably cut it down some. If you use a 6" pipe stack it needs to be 24.33" tall. I am not sure if that was your question or not about the stack. 41.25 sq in of air intake and 110 sq in firebox to cook chamber opening.

I could not get it to copy and paste the link like it is supposed to so I had to just type it out. I like the plans and think it will make a nice looking smoker.

Forgive me for my ignorance.  By pipe stack do you mean the exhaust pipe for the cooking chamber?  If so why does it's height matter?

 

[rasimmo]

Yes I do mean exhaust stack. I went back and added a couple words to make it more clear. Sorry for my grammar. It aint the best sometimes.

I was just going off of what the calculator calls for. I think it has something to do with volume to achieve proper draft. I am not a thermal dynamics expert, just going off of what I think and what the calculator that a lot of folks use for builds say works. I am assuming by your user name that you are an engineer or at least a student. Maybe you can dig up some information to educate us. I would like to know the meaning behind it all myself, but have no idea where to research for that.

 

[bbq city]

Thanks Rassimo.... that was indeed what i'm looking for. .... and VTmecheng the height matters a lot because of the draft the exhaust develops.... hot air rises and the flow of air through the exhaust will create a draft in the smoke chamber and that will draw the hot air from the fire box.... the longer the exhaust pipe the more draft.... until a certain point where the air has cooled of to much to rise ... too long is not good either.... to short and it will not create enough draft..... so you could say that size does matter..... ;-)

 

[vtmecheng]

I would love to see the calculator for this.  You're right about my user name, graduated from Virginia Tech in 2003 with a degree in Mechanical Engineering.  It sounds like the concept of the exhaust pipe length is just that hot air will always want to move towards cold.  The idea of the pipe length causing an increase in flow rate (up to a point) is something I will have to think about though.  It's been a long time since I have done heat and mass transfer, not really what I have done over the past 10 years and it's amazing how much knowledge can be lost.

 

[rasimmo]

http://www.feldoncentral.com/bbqcalculator.html

That is the link to the calculator. I completely understand the knowledge loss. I always say my brain can only retain so much. I have to purge some stuff out to put new in. Sometimes I delete the wrong file and it is gone forever.

 

[vtmecheng]

Sometimes I delete the wrong file and it is gone forever.

This happens to me all the time!  I am actually thinking of going back to school just to relearn some of the basics, like the higher level math classes and maybe a statistics class to start.

 

[bbq city]

Ahum.... sorry guys ..... swapping

 over to a tank build..... gat a free 132 gallon tank as a present today!

 

[bbq city]

20130224_093351.jpg

• bbq city
• Mar 7, 2013

current setup......

 

[bbq city]

20130307_180036.jpg

• bbq city
• Mar 7, 2013

setup to be.......

 

[bbq city]

20130307_180143.jpg

• bbq city
• Mar 7, 2013

mind you ......I'm 6 foot 8 inches ..... not the smallest....:-D