20" RF Plans?

[Barrion2018]

I'm getting ready to start my secound build for my daughter. She wants a RF smoker.

I have a 40" X 20" x 3/8" pipe for the CC, and a 20" x 20" x 3/8" pipe for the FB, but don't have any idea how to build a RF.

I searched a lot of the post on RFs, but could not find what I was looking for, step by step instructions.

I would prefer a set of plans from Frank, but unfortunately, he doesn't have any plans on his site for building a 20" RF CC with round FB.

I would appreciate any and all help

[Big T]

A RF really only differs from an offset by a couple of things.1) The baffle plate and gap. 2) Stack location. All of your other dimensions will be the same. A 20''X40'' CC will call for 20''X15'' FB (112%) a (16'' is 120%) which is a little bit short to work with but certainly doable. A 40 sq inch throat, 3'' stack about 44'' tall or 4'' about 24'' tall. A couple of 3''X6'' air intakes or a single one on the door. The BP is mounted 2''-6'' below the bottom rack (3.5''-4"" for me) Mount it level front to back and end to end with a 2' grease dam at the BP gap. The BP gap is no larger than the throat and up to 75% smaller, I shoot for just under the throat size so approximate 38 sq inches. 'We'll be glad to help you out however we can, just let us know what we can answer for you. If you look at The Mack which is pinned at top of the RF section, you can get a really good idea of what you're shooting for. I know it's square and you're building a round one but the concept is the same. I'll try to find a link to one of my older builds that was a round FB and CC, it was a little bigger but basically what you're wanting to do.

[Big T]

https://smokerbuilder.com/forums/viewto ... =11&t=3243 This might help you out a little more since it's round also.

[Barrion2018]

Thank you very much for the info Big T

Me and my daughter started getting things ready last weekend, and plan on getting started on it this weekend.

My daughter wants to help build it, which I think is awssome. She's even learning how to weld so that she can do most, if not all the welding on it. Last weekend was the firstime she has ever touched a welder. She welded/practiced all day last sunday in 100 degree F weather, and loved every minute.

I'll be asking more questions, and posting pictures as we go.

Thanks again!

[Big T]

That is awesome, Good luck!!

[Barrion2018]

Here's a few pictures of my daughter's RF build, not much to see, but we just got started.

The first pic is of the FB that we had to add a couple of pieces of pipe to make it big enough. This was done last weekend when she was learning to weld for her very first time. I'm so happy and proud of her with how great she is doing.

Her first time ever welding

Cammie 3 .PNG

I got the legs cut, and tomorrow I'll have her weld them inplace, after cleaning all the metal.

[Big T]

[Dirtytires]

Not sure what your plans are as it's not shown in the picture so forgive me if I'm tossing out ideas before you get to them. Many of the "big box hardware store" pits have simple "table" legs which looks like what you are aiming to duplicate. No problem with this but with the weight of a 0.375 thick tank, you will want to add some cross pieces to box it in towards the bottom of the legs. These things are heavy and last thing you want is a hot pit falling over on someone.

By the way, pretty nice bead for a beginner. Keep practicing....she'll be a pro by the time you guys fire up the pit!

[Barrion2018]

you will want to add some cross pieces to box it in towards the bottom of the legs. These things are heavy and last thing you want is a hot pit falling over on someone.

Thank you Dirtytires!

Not in the pictures, are some 1" black pipe I cut that will be for cross pieces near the bottom for bracing.
I will also have some expanded metal on top of bracing for stacking wood, or whatever. "Safety First"

Thanks again for pointing that out.

[Barrion2018]

you will want to add some cross pieces to box it in towards the bottom of the legs. These things are heavy and last thing you want is a hot pit falling over on someone.

Thank you Dirtytires!

Not in the pictures, are some 1" black pipe I cut that will be for cross pieces near the bottom for bracing.
I will also have some expanded metal on top of bracing for stacking wood, or whatever. "Safety First"

Thanks again for pointing that out.

This is what I did on my smoker this spring (very frist time I ever welded also), going to do the same on her's.

Her's is going to be just a little smaller than mine (mine is pictured below), but her's will be a RF.

[Frank_Cox]

Looks great!
I will add some 20” plans with round fire box to the list.

Beginning in August 2022 We are getting ready to start making some rounds for Box plans. [emoji106]


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[Barrion2018]

Thank you Frank!

Let me know when those plans are available.

[Barrion2018]

Question.

While doing some research on how to build a RF, I seen a couple post where guys have used a heat deflector (not exact wording) between the throat and BP. One member siad that (if I remember correctly) it should be approx 12" long.

It sounds like a good idea. Is it? I tried finding the post again, but was unable to find it.

Any info would be greatly appreciated, good or bad.

Thank you

[Big T]

It's called a shadow plate, mounted at the top of the throat just below the BP. Most guys run them about the first 25% of the length of the BP so 12" will work fine. There should be an inch or so air gap between the plates for it to be effective.

[Barrion2018]

Life kinda gets in the way sometimes, my daughter has been busy with her kids the past couple of weekends,and hasn't had time to work on her smoker.

This weekend/tomorrow, she has nothing going on; so she's coming over tomorrow so that she can work on it. I'll post somemore pictures of her progress.

I do have have a couple questions:

1) I read in one of the post that someone use a car or truck hood spring on their CC door, and that it supposedly worked. Does anyone remember that post?
If so, did they use one spring or two?

I ordered a couple to try, but wanted to get a little info from someone who has done it. I'll try and post a picture below.

2) I need help with throat size.
I used the calculator, and it says I need 50.27 sq. in.
While I have been doing a little research on how to build a RF smoker, I found an old post on another form saying your throat (they called it FB/CC) has to be larger than a traditional flow offset smoker due to a RF needs more draft/air flow to work properly.
Is that correct?
If so, how much larger do I need to make my throat?
My daughter's CC is 20" x 40" x 3/8", the FB is round 20" x 20" x 3/8".

[ThinBlue]

I used hood springs on my smoker. I used just one set and got about 20lbs of lift relief from the one set so I would say if you need more relief than that then you might want to double it up. At the end of my video that I did for my cook chamber my buddy briefly talks about what he did to install them but it is a far cry from an outright tutorial. I wasn't there when he did it because he snuck the work in one evening when he had about an hour free-time available.

https://youtu.be/2Wb7-4wFHMM


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[ThinBlue]

One thing to note on the calculator, it was originally designed and intended to be used for reverse flow smokers. I've spoken to Frank about this and he swears by sticking to the calculator for a reverse flow whereas with a traditional open offset you have more wiggle room to do move some of the numbers around and do some different things without consequence.

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[Big T]

Stick with the dimensions from the pit calculator and you won't have any issues. I have built quite a few RF's over the years using the calculator and I've never had any problems.

[Big T]

I just spent about 45 minutes searching for the build that used hood hinges but it was several years ago and I didn't find it. I did stumble across this one that used external gas struts. You can check it out if you'd like and I think he had some info on where he got them from. http://smokerbuilder.com/forums/viewtop ... =11&t=5690

[Barrion2018]

I used hood springs on my smoker. I used just one set and got about 20lbs of lift relief from the one set so I would say if you need more relief than that then you might want to double it up. At the end of my video that I did for my cook chamber my buddy briefly talks about what he did to install them but it is a far cry from an outright tutorial. I wasn't there when he did it because he snuck the work in one evening when he had about an hour free-time available.

https://youtu.be/2Wb7-4wFHMM


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Thank you ThinBlue! That's exactly what I'm wanting to do with the hood springs.

[Barrion2018]

ThinBlue and Big T,

Thank you for that info, I'll stick with the calculator as you both suggested.

Thanks again!

[Barrion2018]

It's called a shadow plate, mounted at the top of the throat just below the BP. Most guys run them about the first 25% of the length of the BP so 12" will work fine. There should be an inch or so air gap between the plates for it to be effective.

I'm hoping to start on the "shadow plate" and BP this weekend, if my daughter shows up.

Today I hope to get the CC legs and suports done, and start on the placement of the "shadow plate" and BP.

My plan is (correct me if I'm wrong), to figure out where the top of my throat will be then measure 1" above that and weld-in the 12" long by CC width shadow plate, then measure 1" above the shadow plate and install/weld the BP.

After installing the shadow plate and BP, I was going to measure ~ 2.5" to 3" above the BP for the bottom of the CC door. My thought is, to do everything I just mentioned before cutting out the door, so that I know where the bottom of the door will be.

Please correct me if I'm screwing up doing it this way.

[Big T]

That is the correct way to do it and certainly will work. I normally try to work the math in forward and reverse so to speak. I like to plan for my bottom door cut to be 1'' below the 3 o clock position on the tank so that my bottom slide out rack can be maximum depth. I shoot for the BP to be 3-4'' below that, then the SP an inch lower and then I see how much room I have to work with on cutting the throat and mounting the FB. If there's plenty of room I go with that method, if it doesn't work out I work it from the throat up to my rack. I mostly use 24'' pipe and there's plenty of room to mount everything using the method that I use but you may find that you have to work from the bottom up on a 20'' CC and that is perfectly fine.

[Barrion2018]

Question of BP lenght.

Following Big T's advice, the gap between the BP and the end of CC should be no larger than the same square inches of the throat.
The ID of the pipe is 19.25",

Again, the size of pipe I'm using for the CC is 20" OD X 40" long X 3/8" thick, the FB is 20" OD X 20" long X 3/8" thick (I know it's oversized, comes in at 150% according to the calculator)

So according to the calculator, the throat should be 50.27 sq in. Going by what Big T said, and using the throat square inches, my opening at the end of the BP should be a max of 2-1/2" to 2-5/8" max, is that correct? seems small.

[Big T]

You'll have to figure out the height of your BP in the CC and measure the width of the CC at that point. It will probably be less than the max width of your CC because it won't be at middle of the CC. Your formula is correct, you just have to use the right dimensions.