100lb Propane Build

[Marcsmith]

what is best for the legs/frame tubes, square stock, angle? and is there a "best width" for the bottom of the frame. if I come straight down from the tank its only about 17" wide Is that wide enough.

I was thinking about putting a cutting board or prep area on the front of the smoker. which would give me a bit more width as well... I'm hoping that I might be able to scavenge some stuff from work. we have a lot of construction going on so hope springs eternal, but we'll see

 

[Berettaclayshooter]

The leg and frame material are totally up to you. Angle is easy to work with. Best bet is to get a big piece of cardboard and lay out an end view of your tank. Determine at what height you want your bottom grate to be in relation to your height, that will be the height off the ground. I would say 1/3 bigger than the cook chamber would be a good size for the base.

 

[Marcsmith]

i figured 36" from the ground, counter top height, is a good reasonable height for the main cooking surface. its what i'm used to in the kitchen, prep/cutting area will be .5"-1"lower. the top of the fire box will end up being a few inch lower.
beretta i see you are a fabricator. 1.5" angle 1/4" thick for main supports. overkill or would 1/8 or 3/16 suffice or 1" angle

i've got a large format plotter so I can print everything out in full scale if I need to.

cooking grates. want the ability to remove them for cleaning. make them such that they can slide out on some U channel or just flat bar supports to keep it simple

 

[Berettaclayshooter]

1.5"x1.5"x .1875" or .250" would be fine for the legs, I wouldn't use .125" that's a little flimsy. What were you planning on using for the grate frame material? For the side supports, angle would work with the bottom leg facing in to give you a shelf so to speak, or are you concerned about pulling the grate out so far and then it wanting to flip, if so "C" channel would be a better option, light stuff would be fine, like .125"-.1875"

 

[Marcsmith]

For the grate supports I was thinking angle or channel. If I did angle I could always weld a tab on the underside of the grate to hold the shelf from flipping if I slide it out too far

For the cooking grates I was thinking of 1” flat bar on the perimeter welded flat on three sides of the expanded metal, with 1” angle along one of the long sides to help prevent twist and sag from repeated heating and cooling.

 

[Marcsmith]

Got a bit delayed by work and life in general. Started marking out the door and a “crosshairs” of sorts on the end where I’ll be cutting the firebox opening. I figure I’ll drill holes in the corners and start cutting on Friday. I really need to make sure the fbopening is cut square hence the cross hairs. Atleast I have some reference points

 

[daveomak]

The FB opening should be half moon... The green area is what it should look like.... in the proper sizing of course...
..........

 

[Marcsmith]

dave,

according my cad drawing, measurements and formula numbers, the A-B chord line on mine should be 3.8" below the tanks horizontal centerline to give the proper area with enough space to allow for a lip when the firebox gets attached

 

[Marcsmith]

Nice cut. Also cut 90% of the door. Waiting on hinges so I can weld

 

[indaswamp]

I'm following this thread...
I have an old 100gal. propane tank and an old 5 gallon tank I could use as the fire box. Might make me a 100 gal. stick pit....

 

[indaswamp]

what is best for the legs/frame tubes, square stock, angle? and is there a "best width" for the bottom of the frame. if I come straight down from the tank its only about 17" wide Is that wide enough.

I was thinking about putting a cutting board or prep area on the front of the smoker. which would give me a bit more width as well... I'm hoping that I might be able to scavenge some stuff from work. we have a lot of construction going on so hope springs eternal, but we'll see

You can always angle the legs to make the base wider than the top for more stability.

 

[Marcsmith]

Remember though a 100gallon is much bigger than a 100 lb tank

 

[daveomak]

14.25x14.25x.7854x40"L=6379 cu. in.
6379x.004= ~26 sq. in.
3" ED calculates out correct....
4" ED is better because of friction loss in a "small ish" smoker.... Measure up from the bottom + the wall thickness of the tank...
AB chord of 12.8", should work...

 

[Marcsmith]

This is what I ended up with.
ED 3.75
AB 11.75

Plugging those numbers in and drawing the half moon in the cad program gives me an area of 31.55

It will probably grow slightly. Once I even out the cut lines. I used a hand held jigsaw. And trying to keep the saw steady and the blade lubricated and following the line made the blade wander a smidge. So I have to smooth out the cuts

 

[daveomak]

It's not a half moon shape... Use a radius of ~7.25", draw a circle, then put in the ED of 3.75".. draw the chord AB...

 

[Marcsmith]

Half moon... well not exactly a half moon. The cut out area looking from the end looks just like the green area ABD in your image above don’t know what the official geometric shape would be called

From the side it looks like the open mouth of Pac-Man

I had difficulty getting the straight and curved lined transcribed on the domed end of the tank.

Did I screw up the cut?

The opening has a larger area than the minimum reccomended by the formulas...

The 3.75 and 11.75 are actual numbers measured at the cut opening

 

[daveomak]

Since you are going to insert the steel plate for the top of the FB into the FB/CC opening, and that will shrink the height of the opening, I would cut it up to 4" height... It's the top of the opening that gives the most area ... You could cut an 1" off of the bottom curve and you wouldn't notice the loss in area, because it would be very little..
It's important to try and get the best air flow possible now... once it's built and you decide it's lacking air flow, it's a PITA to rectify poor air flow..

 

[Marcsmith]

So I did not screw up the cut. Ie I can always cut more. I’d rather have that problem than cut to much and have to add material.

The only thing I worry about if I go higher. Is that I’ll be right up against the reverse flow plate which means that maybe I’d end up with an extremely hot spot on that side of the smoker...

Is That a valid concern?

 

[indaswamp]

daveomak

Do you think a 100lb. propane tank is too small dia. for a reverse flow? The tank I have is 14" dia.

 

[daveomak]

14" dia. will work... The RF plate will weld to the top plate of the FB.... The FB/CC opening will be cut from the top plate of the FB down in that weird circle shape, then welded up to the CC...
Think about cutting the notch, for the FB deeper into the CC so you are not in the curved area... That will make the fit up of the RF plate MUCH easier... You will not have to worry about a hot spot... Using the 2 inlets on the FB, you will be able to control the heat...

Read this....
Cheese smoking in my RF smoker


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