Wood burning stove style reverse flow smoker.

[SouthamptonSmoker]

There is some scrap road plate going at work, from a ditch that we filled with concrete.

This is going to make it heavy but looks good.

It is 15mm so I guess about 5/8'' for you guys.

Looks like I will be using this plate for the baffle plate, and firebox internals, and probably the oven to. This takes away space in the cavity though - to about 7mm. Not a lot of room for insulation anymore. But do you think it is required if the plate is that thick?

It will still have the outer CorTen skin, as i do not want to paint it and like the look of it.

Should i also use this for the internal skin of the cook chamber, I was going to use it just for baffle plate, then normal mild steel inside 3mm with insulation and 3mm CorTen skin on the outside.

[Rodcrafter]

I have never built a design like yours but, I believe if you use this thickness of steel in your design it will act like a heat sink and the FB is going to be the only hot box.

I use thick steel myself (a lot) it requires getting it hot before any air movement works as you want. But as soon as she heats up it is awesome.

jm2cw


Making memories!

[SouthamptonSmoker]

Hi Rodcrafter.

That is interesting. I was a bit excited by free steel, so consider using it as much as I could. May be best to stick with the insulated firebox and oven.

Is this thickness suitable for the baffle plate?

I must admit, I do see some of the thickness you guys use and wonder why so heavy? I assumed this was best practice.

[Rodcrafter]

Where you are putting your “BP” in the upper cabinet, is already going to have a hard time getting hot. It may work but it will take some time to get hot enough if it does.

Don’t get me wrong I like heavy steel, but I believe it is only work in some places.


Making memories!

[SouthamptonSmoker]

The BP is 3'' above the riser, it is the bottom plate on the model, with cut out the opposite end

[SouthamptonSmoker]

I stayed late at work, to start drafting the actual individual parts that will make the cook chamber assembly. So this could get even more confusing now lol.

I am going to stick with 1/4" baffle plate for now then. I can make the hole thing on the pc first, before I need to do anything.

I crept in again on the cook chamber size, as I need a 1" gap for insulation, so I have crept 1/4" of to loose the steel dims on the inside of the cook chamber. I am committed on external dimensions now.

I am making it like a jigsaw puzzle, where the indiviudal plates slot into laser cut notches and you welded the back of the notch like a plug weld. Grind flush. This should give a really good seamless look, with no visible welds. It is however incredibly painful for the head lol, and i have to draw each component, as those parts will be profiled out by a laser profiling company.

Got a few pictures, so you guys can get a feel for where i am going.

The build plate notches are in on the back plate. Does this give a better idea of location. There is one notch too many, as it doesnt go all the way to the end. The right hand side is the end which has the cut out. Which is full width of the cook chamber and 3" deep, which works out the same area as the riser and the required sizes for the cook chamber opening.

[SouthamptonSmoker]

Spent a few more hours after work piecing together the internals of the cook chamber. I had made the wide plate 12mm too long, because I forgot to loose the steel on the inside for the skin plates, this cost me quite a bit of time, as it is a total bugger nut to sculp in on the dimensions, because I am using the edges as datum, means I had to redraw all the notches. Never mind though, as it is a lot easier to re-draw than it is to cut and reweld.

So I didn't make a huge amount of progress. But I got the baffle plate installed in the model. will put some supports for the rack, but I wont be back at work until Monday. Unless I can find a decent enough PC to run the package on at home.

I am also leaving the most difficult to last, the firebox and oven is going to be some complex assembly, and I am pulling inspiration from everywhere including commercial heating systems. For now i am keen to get the cook chamber drawn, and ordered, whilst I work on drawing the firebox and oven.

This weekend will be finishing the bars, welding the 20 caps on and dimensioning them, this will take most of the weekend, as I will need to chase up on the dimensions, to ensure it is on the money, which might take a few stabs of pulling it in and out of the lathe.

The profiles should arrive Wednesday, so keen to get the bars knocked out. I got some stainless steel buttons heads ready, and as soon as it turns up I want to put it together to get a feel for the thing, should look good.

It is hot here in England, we are not use to 30degree heat, unfortunately I will be in the workshop, I don't like opening the front door as it faces the street, and I got a lot of stuff to steal, by the time the bbq is done, no doubt the weather will have gone, so I best crack on.

[SouthamptonSmoker]

Completed the bars, which mean I can go enjoy the sun now. I made a jig out of some squares I had to get the bars all the same size. Put a piece of paper one end, and when the bars slide in with a bit of play then I knew they where the same size.

Once I had blended all the welds, I mounted some of them in there to get a feel for how it will look. The spacing is slightly tighter than on the bbq, but this is more or the less how the 'splash back' area of the bbq will look.

Few pictures of progress.

[Big T]

I'm not sure how well it'll work but it's going to look great!

[Smurf]

good luck very neat build.

[ajfoxy]

It certainly is going to be a thing of beauty. And if even RC says 15mm is too thick then it must be so, as he is the king of using THICK steel...

Myself, if that steel is free, grab it and hoard it. There are soooo many projects that might require steel that thick. As the old adage states.... "steel in your hands is better than in the hands of the steel merchant". ... well it might have been a tad different but you get the drift.

[SouthamptonSmoker]

Thanks guys.

Next update will hopefully be Wednesday, when the side plates turn up and I can get the frame assemble.

[Rodcrafter]

Nice work!


Making memories!

[pr0wlunwoof]

My buddy who helped with my builds is a machinest. You guys think allot alike. Looking good keep up the hard work.

Sent from my Nexus 9 using Tapatalk

[SouthamptonSmoker]

Plates didn't turn up until Thursday. I have been bbq'ing today in my current one, for my dads b'day tomorrow. Got a few pics of the new bbq progress and smoking on my current one.

[ajfoxy]

Can't wait for this thing to come together and release some smoke. Just to see how it all works.
Nice Q and hope you dad had a great birthday.

[Big T]

[SouthamptonSmoker]

So getting stuck in with the drawing, and firming up on all the geometry of the cook chamber. So I just want to sound out some of that geometry.

I been use the Feldon calculator, and been working that the cook chamber opening should be the same area as the area under the baffle plate and the opening at the opposing end of the cook chamber.

I will be insulating the entire cook chamber, with 25mm fibreboard, so has taken a while to draw a box in a box, and also reduced the area. So i run the calcualtions again, I decided in insulating the riser too, and this also grew as i wasnt keen on having it stick out too far across the frame, it is now about half the width of the frame. Was keen to leave the other side clear for a grill. I still have a pretty large stove area in front of the riser too. It makes it look a lot more like it will actually work too.

Now down to my questions.

My cook chamber internals are now 938x338x437mm, crunching that into inches in the calculator gave me a box to chamber of 40.71'' squared. Because I dont want my riser sticking out past the frame (the frame is 6" wide but we loose 1" to bar) mean internally i only got about 2" (more like 65mm) once insulated. So it got wide to accomodate that.


Then we get up to the cook chamber, well this is already wide, in fact wider than the riser, so we loose a tiny bit of height to get the same area, the baffle plate is 60mm above the bottom of the cook chamber and riser inlet. The gap at the end is the same as this.

So does that sound right?

Now if the geomtry is correct, not so keen on welding the baffle plate in, was thinking to weld a profile in which is essentially is a 1" perimeter, then weld a wider profile underneath, with about 1" larger all round which will create a 1" lip, then just drop the plate or bolt it in. I could even put a seal there. Just concerned with 60mm gap at the end, and at 60mm gap underneath, i will never get under there ever again.

Saying that, i will never see the insulation again, and I am ok with that. Your thoughts?

Finally got some hinges and a latch for the door for the cook chamber, real nice bling

Some pictures, i have made some components transparent on some so you can see more detail.

Kason_778.jpg (6.07 KiB) Viewed 386 times

door hinge.png (172.05 KiB) Viewed 386 times

[pr0wlunwoof]

I like that door hinge.

[SouthamptonSmoker]

I was wondering if anyone could provide some feedback on the dimension, in particular the baffle plate height etc.

With this type of design, it is going to be near on impossible to correct a failure, without replacing the associated sheet. Works well to assist with alignment and building, but if it is wrong, is pretty much scrap.

By the end of the week, i would like to be in a position to put the cook chamber and associated components out to quote.

Thanks in advanced!

[Rodcrafter]

I am guessing when hear you say Cook Chamber. Are you talking about the top cabinet or the one to the right of the FB? Unless I missed something you aren’t going to have one in the lower cabinet. And the one in the top cabinet is really going to be a shadow plate in my opinion. That being said the elevation of the plate is based on the throat size. Example if the throat is 4”x12” and the plate will be attached on one of the long sides , you would need 3” between the opening and the plate to prevent choking the draft. If the opening were in the center of the CC you would only need 2”.

jm2cw


Making memories!

[SouthamptonSmoker]

Hi Rodcrafter, thanks for the reply - Yes the cook chamber is the entire top section. The oven is a different device, which will not want any smoke passing internally just heat around the outside. The firebox is purely the left hand side of the bottom section. This will be about 17" square internally then i will loose more for a fire basket, but i am at 183% recommended side, so have no issue loosing some firebox space.

The first attachment of the last post with pictures show some detail. It is easy for me to see as I am drawing it, would it help if I annotated what is what. In that picture the baffle plate is in there, and has a transparent blue hue to it. You can also see the cook chamber to fire box opening and that the baffle plate stops short of the end on the right hand side of the cook chamber. The riser section, where it ends that is the bottom of the cook chamber, the section in there only passes through the insulated section through the outer box into the inner box.

My opening from cook chamber to firebox is 68mm x 410mm (2.67" x 16.1") shooting for about 40.7". I end up just over.

Because the width of the cook chamber is already wider than the opening to firebox, I reduce the height a little and come out with 60mm x 437mm (2.36" x 17.2") - i am guessing this is the throat?

At the end i have the same gap, 60mm x 437mm. So I leave 2.36" at the end of the baffle plate.

I am not sure what a shadow plate is? Can you explain a little. I am not sure if you are you saying this wont be a reverse flow smoker? Or because it will be plug welded rather than fully welded throughout? I am a little green on all the terminology.

Essentially I am going to have the hottest section of the firebox fully open across almost its entire width, but only 2" or so deep. I would of thought the heat would of roared up there, better so than an offset design, because of the convection of heat. Once the baffle plate has seen that heat, it will radiate which is not influence by direction, so will heat that entire plate up?

Still a bit uncertain, but does seem according to what you say, it appears I am about right for the dimensions?

But just bit of understanding the difference between a shadow and baffle plate, and engineering behind each would help me understand a bit better.

[SouthamptonSmoker]

Some pics of the meat the weekend. Lamb shoulder was the nuts, bone pulled straight out of it clean.

[SouthamptonSmoker]

Hi Rodcrafter, thanks for the reply - Yes the cook chamber is the entire top section. The oven is a different device, which will not want any smoke passing internally just heat around the outside. The firebox is purely the left hand side of the bottom section. This will be about 17" square internally then i will loose more for a fire basket, but i am at 183% recommended side, so have no issue loosing some firebox space.

The first attachment of the last post with pictures show some detail. It is easy for me to see as I am drawing it, would it help if I annotated what is what. In that picture the baffle plate is in there, and has a transparent blue hue to it. You can also see the cook chamber to fire box opening and that the baffle plate stops short of the end on the right hand side of the cook chamber. The riser section, where it ends that is the bottom of the cook chamber, the section in there only passes through the insulated section through the outer box into the inner box.

My opening from cook chamber to firebox is 68mm x 410mm (2.67" x 16.1") shooting for about 40.7". I end up just over.

Because the width of the cook chamber is already wider than the opening to firebox, I reduce the height a little and come out with 60mm x 437mm (2.36" x 17.2") - i am guessing this is the throat?

At the end i have the same gap, 60mm x 437mm. So I leave 2.36" at the end of the baffle plate.

I am not sure what a shadow plate is? Can you explain a little. I am not sure if you are you saying this wont be a reverse flow smoker? Or because it will be plug welded rather than fully welded throughout? I am a little green on all the terminology.

Essentially I am going to have the hottest section of the firebox fully open across almost its entire width, but only 2" or so deep. I would of thought the heat would of roared up there, better so than an offset design, because of the convection of heat. Once the baffle plate has seen that heat, it will radiate which is not influence by direction, so will heat that entire plate up?

Still a bit uncertain, but does seem according to what you say, it appears I am about right for the dimensions?

But just bit of understanding the difference between a shadow and baffle plate, and engineering behind each would help me understand a bit better.

Is anyone able to provide some feedback on the above?

Thanks in advanced.

[SouthamptonSmoker]

So pretty much got the drawings to quotable stage for riser and cook chamber, so I am going to go ahead and see what the cost is, I can still move the baffle plate or shadow plate easily, before I commit on the order, the price would be the same. I see another post with a shadow plate, this was real small though? and they had it under a baffle plate.

I have a couple more cad images, i have made transparent the door, which is still just block solid at this stage, with some key dimensions made out. IE latch and probes.

My bling arrives too, to fit the huge latch, my door opens vertical. So this adds a couple more days to the door drawings as I am going to add stainless steel gas struts to open the door, so door needs good seal and insulation, to ensure they dont go bang lol.

I think i will go ahead with the riser once the quotes comes back, this is a pretty safe part, incase my tolerance is to wide or loose. That way i can update the drawings to reflect this. laser cut profile tolerance is 0.25mm. So i added 0.5mm to the slots, the guys didnt seem to know much more about whether it would fit, so i need a trial.

Oh, and turns out this will be dull polished stainless, not CorTen. Just because.....