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Firebox material thickness

 
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Tue Mar 12 13 3:15 am    Post subject: Firebox material thickness Reply with quote

Hallo.

First of all i just need to say that this is a great forum,
I have read a lot of good posts in bbq building here.
I´m from Finland and around here we don´t really have real bbqs just grills and that is something we have do something about isn´t it? Very Happy

I´m about to start building my first ever bbq.
It will be a offset smoker made out of a 300l (68gallon) stainless steel water heater tank.

The idea is to cut down the tank a litle bit (about a third)
and repurpose the cutout piece as firebox.

But reading this forum and looking at other builds i have seen that much thicker material is usualy used for the firebox.
the tank is 2mm (.08 inch).
I would use thicker material for the ends doh. 4 or 6mm (.16 or .24inch)
Is the 2mm (.08 inch) tankpiece to thin or will i have to make a innerpiece and isolate it to get to work allright?

Do the fireboxdoor need to be seald or can it be a litle leaky? And if it should be sealed what do you usualy use for seal? fibreglass rope? something else?

You all have a nice day now!
//Magnus
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k.a.m.
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Joined: 12 Dec 2007
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PostPosted: Tue Mar 12 13 8:14 pm    Post subject: Reply with quote

Welcome to the ring Magnus, looking forward to seeing some pics of your cooks and following your cooker project. Smile
I am not sure of your knowledge of SS and cookers but they do not always go together because of the SS moving when heated. Things that fit cold do not always line up when heated, I would not recommend a wall thickness of anything less than .250 for a firebox whether it be carbon steel or SS.
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Tue Mar 12 13 11:18 pm    Post subject: Reply with quote

Well thank you Very Happy
and thank you for the answer.

i know stainless but i have not used it in this way before doh.
I guess the cooker part of the smoker should not suffer all to much by the heat due to the low temperature and hopefully even heating.
How much problems should i expect from the firebox? anyone here that tried? or have a link to someone that have?

I´ll have to rethink the firebox then.
this is a low budget project and am going to use alot of repurpoused materials and being in the boatindustry stainless is the cheapest metal available Rolling Eyes
the thickest steel we have around is .240
I guess i have to decide if I´ll use that or trow some money on the thing and buy thicker steel. Wink


k.a.m. wrote:
Welcome to the ring Magnus, looking forward to seeing some pics of your cooks and following your cooker project. Smile
I am not sure of your knowledge of SS and cookers but they do not always go together because of the SS moving when heated. Things that fit cold do not always line up when heated, I would not recommend a wall thickness of anything less than .250 for a firebox whether it be carbon steel or SS.
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GF
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Joined: 30 Apr 2011
Posts: 2792
Location: Greenwich, CT.

PostPosted: Wed Mar 13 13 12:28 am    Post subject: Reply with quote

Smokin Finn, welcome. Very Happy

Just a thought on your cooker plans. Given the thin wall stainless and the average temp., (google says 41F.), you may have problems with heat retention.

Not trying to discourage you at all, just my thought, I've been wrong before. Wink

Good luck. Very Happy
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Wed Mar 13 13 1:45 am    Post subject: Reply with quote

GF:
thanks

yes it might be a problem in the spring and autumn when temperatures are lower, this time of year it probabily would be impossible we are at -15c today (5 farenheit)
But I guess i will find out. Rolling Eyes
Worst case i learn how not build a bbq.
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Cat797
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Joined: 18 Feb 2010
Posts: 717
Location: El Paso, IL

PostPosted: Wed Mar 13 13 2:42 am    Post subject: Reply with quote

Smokin Finn,

6mm will be fine for the firebox if you have some. Although, I'm not sure about the feasibility of mating SS with carbon steel.....I would take k.a.m.'s suggestions, as he is very knowledgeable on these cookers. Personally I would use carbon steel if you have it due to the nature of SS to move when heated. Obviously if you have some free materials to use might have to rethink the application. For instance, you may be able to use the 2mm material if you went with a insulated vertical type smoker, where you could get by with a smaller fire as it sits underneath the food. You may even be able to use your tank for that........Just thinking out loud here.

Do you have any flat material or is it only the tank?

Good Luck,
Ed
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Wed Mar 13 13 3:06 am    Post subject: Reply with quote

The 6mm will also be stainless of course. No mixing of materials here. Right now i just have the tank and some thicker material for making hinges. But I´ll get some flat 6mm to make the firebox out of.
I actually thought about building a vertical smoker first but opted for offset smoker instead.

and thanks for the good luck wishes it kind of sounds like i will be needing them
Cool
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Wed Mar 13 13 3:10 am    Post subject: Reply with quote

Just found this build.
http://www.youtube.com/watch?v=gUc3xzbOFCc
seems to be build entirely out of a water tank (same type of tank i am using but mine is larger in diameter)


Last edited by Smokin Finn on Thu Mar 14 13 11:41 pm; edited 1 time in total
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Maniac
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Joined: 02 Oct 2010
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PostPosted: Wed Mar 13 13 7:27 am    Post subject: Reply with quote

Smoking Finn ...welcome aboard Exclamation I am looking forward to your build. I wish you the best on what sounds like a well thought out build. I like building with repurpoused materials when ever I can. If you work with stainless in the boating industry then you have a fair knowledge of working with SS which will help you make good decisions. keep us posted.
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Wed Mar 13 13 12:37 pm    Post subject: Reply with quote

Thanx Maniac
unfortunately i usualy don´t do metalwork on the boats but i´m well acquanted with the ss anyway.
I´ll keep you guys posted when things start happening. we had a snowstorm last night that stopped me from finishing cutting the tank. (I don´t have room for it inside the garage right now so i´m about to cut it outside in my shed which turnd out not beeing all to snowtight in the storm)
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Mikeydidit
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Joined: 27 Sep 2011
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PostPosted: Wed Mar 13 13 9:28 pm    Post subject: Reply with quote

Smokin Finn

Welcome and good luck on your build. These guys on here helped me a lot with mine before and after the build. So your getting good advise.. I think the one thing I could tell you that will help you the most is take your time. Measure three times and cut once. Make sure everything is level (again several times and angels) and then tack it and check it again.

Do that and you won't have to redo anything and you will come out with something to be proud of..

Good luck and keep us posted on your progress.

Mikeydidit
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Thu Mar 14 13 3:02 am    Post subject: Reply with quote

well thank you.
I´ll do my best not to rush it, but i get a little bit carried away sometimes. Rolling Eyes
I did cut down the tank tonight.
Now i have to make the hinges and after that I´ll take it with me to work to get it welded back together and get the hinges on before i cut the door out.
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Sun Mar 17 13 1:36 am    Post subject: Reply with quote

I was recalculating the firebox using Feldons bbq calculator today. I have read earlier and it also says in the calculator that a slightly oversized firebox is preferable. how much is that?
46% oversize to much? can it be to big? should the size calculated be the total size of the firebox or the space above the coal grate?
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Maniac
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PostPosted: Sun Mar 17 13 2:04 am    Post subject: Reply with quote

Smoking Finn

IMHO I think 46% is a little to much. 10 or 15% is more reasonable. I did my calc as the whole box not above the great...good luck.
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Sun Mar 17 13 2:24 am    Post subject: Reply with quote

Maniac wrote:
Smoking Finn

IMHO I think 46% is a little to much. 10 or 15% is more reasonable. I did my calc as the whole box not above the great...good luck.


Ok. thanx.
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Smokin Finn



Joined: 10 Mar 2013
Posts: 17

PostPosted: Sun Mar 17 13 3:54 am    Post subject: Reply with quote

Here is a little sneakpeek on the hinges.
the hinge half is still pretty ruff, i´ll take it with me to work and beltsand it to to the final shape and round the edges on monday and make the 7 others if am pleased with the look.


Not still 100% shore about the "llightening holes" yet doh.

Here is a link to my bbq calculations:
Link to BBQ Pit Calculator
any thoughts on that? Very Happy
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