Scuba tank mini reverse flow - first build

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Wow how did I miss that? I am sure the first mini I saw must have been Smokin Steve's!. So now that I have seen better pics of his build I am glad I have not welded the top plate to my firebox. I will get a longer piece of steel for the top to make the reverse plate in one piece.

Two questions though.

1. what size do ya think  his chimney is?

2. Any problem with putting my firebox door towards the front of build?
 
 
Jock,  Thanks for finding Smoking Steve's scuba build thread,  very interesting and entertaining read. 

Toby, 

See Steve's thread post #115, his stack size is 1 1/4". 

Putting the loading door on the front is a matter of convenience / personal preference.   In my opinion it is more important to locate your air intakes opposite the CC opening.  This will give the air a straight line flow.  Looking forward to another mini build!

RG
 
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Thanks Radio Guy, I just need to figure out what kind of vent I want to do now that I have a welder, sliding or rotating. 
 
 
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Got the main part of my firebox welded up today with my new/used Lincoln 100 weld pak. Not as smooth as the 220 rig I borrowed but it'll get er done. Also need to get an auto darkening helmet! The cheap helmet I got with the rig is so scratched up and covered in mystery goo that I could not see to follow an edge.
 
Well I now have a door on my firebox.  I was at the welding supply and they had these beautiful pre-made barrel hinges with brass trim and zerk grease fittings.They are made with a kinda wedge shape so you have some meat to weld to. Well Being the inexperienced welder that I am, I could not figure out a way to get them jigged up or clamped in any kind of stable position. So after about 30 minutes of tilting my head back and forth trying to find "straight" I finally got the nerve and just held them while I tacked them in place.. Of course when I tried to open the door they were off by at least an 1/8" at which point we had a little conversation with the hammer and now I have a door that shuts tight but I am fairly certain I could win the ugliest welds of the year award .
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Thanks Radio Guy, I just need to figure out what kind of vent I want to do now that I have a welder, sliding or rotating. 
 
I have both types on three different smokers. On one smoker the rotating one doesn't have the capability to close all the way.  I think the most important part is getting a tight fit on which ever way you go so there aren't any air leaks. Also being able to close them off all the way is an important feature for me, I like being able to extinguish the fuel so I can use it again.

Now how about some more photos!!!
 
Dirtsailer  I have some pics coming but right now I need to get some ABT's and chicken in the kettle.
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Q-view and firebox door tomorrow. Hopefully I will have the single piece firebox top/reverse plate and tank cutout figured out.
 
 
Sorry I forgot to take Q-view pics but here are the firebox door and the tank cutout. I calculated the top cut at 2" from the bottom of the tank which leaves the inside width at 5-7/8".  I will use a single 5-7/8" x 23"' x 3/16"' plate for the firebox top/reverse flow plate. The firebox to cook chamber opening area under the plate is 6.5"

700








 
Kevin, morning......   I just went through your numbers for you..... couple of questions.....  

ID of tank is 6.75" X 23" length ??

Then the FB should be  275 cu in or larger

Chimney  41 cu in or larger..  2 1/2" black pipe X 10" X 12" or so tall  (due to the lack of total height necessary for a good draft, like 30-40")

FB/CC  opening  2.2 sq in or larger

I think, given the size of the smoker, this build will work well......   There are some considerations that need to be valued in a build this size... exaggerate some dimensions to get good air flow.....   I think you have done that....   the exhaust is a concern...  A 12" x 2 1/2 black pipe exh will give in excess of 60 cu in...   I think that will work, once the stack gets warm....  hard to tell....  50+% increase over the calculator....   Dave

 
 
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Made some  progress yesterday, got the firebox/baffle plate welded on. I also ordered some stainless spring handles. Still need to decide on how I want to do the hinges for the cook chamber door. I have some stainless marine hinges that bolt on or  go the traditional barrel style using rod and tube.  Always glad to hear any ideas or input from the forum.




 
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Kevin, evening...... for the CC door, think about tabs..... just lift the door off and set it down....  no hinges....   would be really simple.....

Dave
 
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Dave that's sure using the K.I.S.S. method! I could just mount the handle in the middle of the door, it does have flanges already, no tabs needed. It could serve double duty as a small shield for when the BBQ bandits attack.
 
 
Going to use a piece 10" x  2" I.D. x 3/16" piece of black pipe for the chimney which will stick 2" into the chamber.  Seems a little overkill with the wall thickness but it was free so that's what I will be using, my only concern is the depth into the cook chamber, does 2 " seem like too much? my ocular calipers say about an inch.
 
 
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 2 1/2"Hole for chimney in Chromoly Vanadium Scuba Tank vs. Tobycat

Hole. 1/2 way cut and still fighting!

Tobycat. Qty. 1 craftsman 5A drill melted  Qty. 2.   2 1/2"Milwaukee hole saws with no teeth, Tobycat now contemplating hammer and chisels...
 
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So I am resorting to techniques I have not used since I was a kid building go-carts
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to get this hole made for the chimney. The hole saw worked OK for getting through the actual side wall of the tank but where it is cutting vertically through the end of the tank the wall thickness is at least 1/2". It is easy enough to drill this stuff but it absolutely kills blades of any type. So getting back to the go-cart thing  I am drilling small holes around the perimeter and when I get the piece knocked out I will clean it up with a file or die grinder.

Edit;  I stand corrected, snaps drill bits too.
 
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