Build.Me.A.Smoker question or Attn Paco & Squib

[GringoSalado 1652]

Not sure if they made it over, but I'm building a smoker, and I have a question:

How do I cope pipe to a semispherical shape? Pipe is 20" casing (firebox), round shape is the end of a 500 gal propane tank.

Asking for a friend.

 

 

I found an online template maker for any pipe, any angle, but not for coping to a hemispherical shape (end of propane tank).

[baboso 6102]

20" template with cardboard, mark out on end of propane tank with soapstone.  Cutting torch and an angle grinder.

[GringoSalado 1652]

I don't think it is going to be as easy as you make it sound. Care to elaborate some?

I'm thinking a (semi-) circular hole in the tank and cope the casing to mate that would be the cleanest build, but I'm not exactly sure how to do that.

Or I could just cut the tank in semi-circular shape, insert the casing, and then mark and trim it. That may be the way to do this. Is that what you meant? Am I overthinking this?

Gracias baboso,

[Paco 1952]

I eyeballed the fuck out of it. I had a square going on the end of the tank, so it was a matter of projecting vertical lines down the end, which was still janky as hell. I'll try to find some pictures of the layout.

[Paco 1952]

If you can tell by this picture, I only had to lay out a horizontal cut, and then a radial? cut along the bottom. Once those lines were laid out I was able to eyeball some blue tape from the top line down to the smiley face cut.

That's a lot of words to say no, I don't know how to lay out a circle on the end of a propane tank.

So now I'm thinking...can you position the firebox piece as close as possible to the end of the tank. Take a yardstick, hold it against the side of the firebox, and sliding it against the curve of the tank make a mark. Keep the yardstick level with the world as you slide it. Does that make any sense?

[GringoSalado 1652]

Awesome Paco, glad you made it over. Like you mentioned I was thinking of setting the casing on some pipe stands up next to the tank and using a straight edge to trace / mark my end cut there.

 

I'll get some pics up once I have some meaningful progress to show.

[Paco 1952]

That sounds like a good simple solution.

[GringoSalado 1652]

Finally got around to it. For various reasons I'm turning this over, and since I have access to a fork lift it made sense to cut the firebox first while still upside down (hope these pics show up).

 

Instead of a straight edge I used a piece of 1/4" tubing I had laying around stuck a piece of soapstone inside it.

 

[Johnny Chimpo 489]

Can’t see shit Captain 

[GringoSalado 1652]

Well shit.

 

Fucking Google 

[GringoSalado 1652]

[GringoSalado 1652]

[GringoSalado 1652]

For my next question, this is going to be a reverse flow with a warming cabinet mounted above the firebox, that will extend 16" above the tank.

 

 

So should I go with a 4" or 6" smokestack? 

[luke duke 6447]

Where’s the rest of the firebox?

[RoundRobin 828]

Go with 4” but tell her it’s 6”. 

[luke duke 6447]

6”
Too much exhaust is rarely a problem

[Steel Shank 9533]

Yeah, I think I'd want a bigger firebox. You want space for flexibility with the fire.

[DCA_HORN 725]

So I'm sure there are smoking physics that I'm too much of a novice to understand but why not just cut off the end and weld a circular plate and attach the firebox to that?

[GringoSalado 1652]

Yeah, I think I'd want a bigger firebox. You want space for flexibility with the fire.

It's a 31" piece of 20" casing. I thought it was overkill.

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[GringoSalado 1652]

So I'm sure there are smoking physics that I'm too much of a novice to understand but why not just cut off the end and weld a circular plate and attach the firebox to that?

I thought of that. Honestly I just wasn't willing to make such a big cut right off the bat.



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[luke duke 6447]

It's a 31" piece of 20" casing. I thought it was overkill.

 

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It’s the diameter in question, not the length.

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

[Paco 1952]

500 gallon tank needs a big fire.

[GringoSalado 1652]

15 hours ago, luke duke said:

 

It’s the diameter in question, not the length.

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

I don't trust that calculator, the firebox on the 1k gal smoker I use is 75% too small according to that.

 

 

We'll know soon enough...

Edited April 20, 2019 by GringoSalado

[luke duke 6447]

I don't trust that calculator, the firebox on the 1k gal smoker I use is 75% too small according to that.
 
 
We'll know soon enough...

I don’t trust it 100% either, but I do think that the diameter of the firebox should match the diameter of the pit for optimal results.

[drt 645]

This should be moved to Hobbies and you should post more pics.

[GringoSalado 1652]

On 4/20/2019 at 3:56 PM, luke duke said:

 

I don’t trust it 100% either, but I do think that the diameter of the firebox should match the diameter of the pit for optimal results.

 

Not that I disagree but that would be a 41" firebox. The 20" casing and the propane tank were free/I already had those. So I welded them together.

 

On 4/21/2019 at 9:17 AM, drt said:

This should be moved to Hobbies and you should post more pics.

I'll have more pics this week.

[luke duke 6447]

I get it. See if it works.

[GringoSalado 1652]

On 4/22/2019 at 10:01 PM, luke duke said:

I get it. See if it works.

I was pretty fucking confident until you assholes criticized my firebox. But if it doesn't work as configured now modifying it to a square 41" firebox will work with the current design, as you'll see. So provided I live to finish it we'll get to see how well, if at all, it cooks. Hoping for a cool thread so thanks for all the comments.

More pics

[GringoSalado 1652]

My next question is about the counterweight. Unfortunately no pics but I tacked a piece of angle at a 45° to the center of the lid, and measured out 1/2 the width of the lid to find the equilibrium moment, or some fucking thing I'm not an engineer,  of the weight of the lid. IOW if you put 165 lbs (lid weight) at that spot the lid would, in theory, be in balance. But of course you don't want that, you want the lid to stay closed, and open. So I just picked an arbitrary amount to place my counterweight completely above that point.

My counterweight of choice is a forklift propane tank. I didn't post this is "shit you heard in a bar" but a drunk redneck from Tyler I was talking to at my local place swore up and down that a small propane tank filled with sand would be sufficient for even a 48"* 500 gal pit.

So then I calculate the weight of my lid (165 if I recall correctly), and calculate the weight of my forklift propane tank filled with sand, and decided I'd better extend it out horizontally for more leverage because it was only going to be like 95 lbs. full of sand.

-----------------------------------------------------

tldr

I guess my question is how the fuck do you design/position your counterweight.

 

 

 

* Also wedded to a 48" door as this thing is meant for whole hogs.

Edited April 24, 2019 by GringoSalado
wtf

[luke duke 6447]

But if it doesn't work as configured now modifying it to a square 41" firebox will work with the current design, as you'll see.

I think anything over 30” would probably do the trick. Or what you have now may do the trick.

[luke duke 6447]

This is how Klose does their counterweights on larger pits.

[kevwun 16294]

The firebox is also supposed to be mounted where it is butted up against the end of the cooking chamber and the top of it should be in the exact middle of the cooking chamber.  I think that end of your pit is going to be much hotter with the way it is underhung.

Edited April 24, 2019 by kevwun

[GringoSalado 1652]

50 minutes ago, kevwun said:

The firebox is also supposed to be mounted where it is butted up against the end of the cooking chamber and the top of it should be in the exact middle of the cooking chamber.  I think that end of your pit is going to be much hotter with the way it is underhung.

That's sort of by design, tha warming cabinet is going over the firebox.

 

Edit:  the top of my firebox is 7" below the bottom rack.

 

Edited April 24, 2019 by GringoSalado

[kevwun 16294]

Didn't think about the cabinet. I wouldn't worry about the welding part.  What you have put together so far looks good.

Edited April 24, 2019 by kevwun

[Steel Shank 9533]

I appreciate that I'm not the only one around here laying some serious pipe.

[GringoSalado 1652]

Warming cabinet mocked up, not quite square in the pic.

Like DCA Horn upthread you might be thinking "wtf, why not just make a square firebox under the warming cabinet" and that's cool because I'm thinking it too. But I really wanted a round firebox. This started out in my head as a reverse flow w/ round firebox to cook 2 or 3 pigs because that's what's on the menu and I had this tank and a bunch of casing. But I also need some ribs capacity (also on menu) so I added the warming cabinet. I'm hoping to actually cook baby backs in there. We'll see if it works.

 

My counterweight didn't work for shit, no amount of weight was going to keep the door open. So I managed to mock it up w/ the door open:

Since my first two versions were too short to keep the lid open I threw a few things and then over corrected on my third try. Fucking thing is like 10 feet in the air when the door is closed but it works, it now holds the door open, just barely, but it's empty (haven't added any sand to the tank). 

The door is still pretty heavy when it's about half way open, but it isn't very heavy when closed. So if I add a bunch of weight to make it easier at 1/2 open I don't think it is going to stay shut very good. I'm not sure if there is any way around that, so something to think about when you decide to cut a 165 lb door.

[kevwun 16294]

Here is how Lonestargrillz does their counterweights.  I like it.  The square tubing is packed with something to make it heavier.  Not sure what it is, but it is packed tight and doesn't move at all.  I don't have a picture of the side view, but the mounting brackets are sloped toward the back of the pit to make it lighten the load as soon as you open the door.

Edited April 25, 2019 by kevwun

[Steel Shank 9533]

Gringo, you should take a look at the size of the box in the pic above and in the pics Luke posted of the Klose pits. Large fire boxes. You are at a stage that you can make an adjustment in the size that will be a whole lot easier than doing it later. Might slow you down a bit, but later on you'll be glad you did. This is coming from a guy who wishes he had a larger box on his pit.

[Paco 1952]

Give me a square firebox all day long over round, but that's just me. I have no scientific data to back this up.

[kevwun 16294]

I've had pits with both and I like square better.  It's easier to work with the fire in a square one because there's more room.

[luke duke 6447]

[GringoSalado 1652]

10 hours ago, kevwun said:

It's easier to work with the fire in a square one because there's more room.

I'm the opposite, I like the natural air gap at the bottom, but I grew up cooking on Oylers. Every square box I've used needed some janky tray to elevate the wood.

 

I'll have some more pics later

[kevwun 16294]

My box has a grate cut out of .5" plate that slides in to place in between some brackets welded to the inside of the box.  It can't go anywhere.

[William_Cannon 86]

Gringo, you should take a look at the size of the box in the pic above and in the pics Luke posted of the Klose pits. Large fire boxes. You are at a stage that you can make an adjustment in the size that will be a whole lot easier than doing it later. Might slow you down a bit, but later on you'll be glad you did. This is coming from a guy who wishes he had a larger box on his pit.

Esto. You’re at a point where you can change relatively easily. The firebox does look a wee wee.

[GringoSalado 1652]

Trying to tapa talk a pic of the maiden cook, fingers crossed.

Props to the dude up thread who predicted the hot spot.

Empty the top cabinet rack was only 20 degrees cooler than the hottest tank rack, but when loaded (2 pigs & 15 or so ribs in tank plus 60 racks in the cabinet) that grew to 40 deg.

No problem whatsoever in making or holding a temp. No lid related injuries.

I give it a solid B at this point I guess. Pigs and ribs should be off soon, I'll grab some more pics

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