The Texas BBQ Forum

hi all-

first time poster long reader-

I plan on building a offset with tuning plates.

I have order a piece of roller steel 22 x 44 x 1/4 with a 18.5 cubed FB. According to Feldons the size diff is 118%.

For the other factors, chimney dia and length, CC to FB opening, and air inlet, should i use the calculator still set to a 118% size diff or should i set the calculator to 100%. size diff?

example -

@ 118%
5" chimney is 16" high
CC to FB is 50.65 square inches
air inlet 19 square inches

@100%
5" chimney is 14" high
CC to FB is 45 square inches
air inlet 17 square inches

when i write i down is seem like such a small difference? Really interested to here thoughts on this.

Many Thanks

Welcome

auscruz wrote:hi all-

first time poster long reader-

I plan on building a offset with tuning plates.

I have order a piece of roller steel 22 x 44 x 1/4 with a 18.5 cubed FB. According to Feldons the size diff is 118%.

For the other factors, chimney dia and length, CC to FB opening, and air inlet, should i use the calculator still set to a 118% size diff or should i set the calculator to 100%. size diff?

example -

@ 118%
5" chimney is 16" high
CC to FB is 50.65 square inches
air inlet 19 square inches

@100%
5" chimney is 14" high
CC to FB is 45 square inches
air inlet 17 square inches

when i write i down is seem like such a small difference? Really interested to here thoughts on this.

Many Thanks

Welcome to the forum auscruz.
I would use these numbers.
Link to BBQ Pit Calculator
On the 2" x 5" intakes go up to three instead of the 1.90. It is better to have and not need than to need and not have.
On your firebox to cook chamber opening use a 12.5" wide x 6.25" tall half moon and add a 1.5" grease bridge.
If you need help with that let me know I will explain.

thanks KAM-

This is what the Trapezoid-shaped Throat Opening calculator on plantcalc.com spit out with a 1.5 bridge (math is hard glad someone else is doing !)
Top Length: 18.439
Bottom Length: 11.091
Height of cut-out: 3.5

Do you see any problems going with this ?

Also - I like the look plenums and stack what are you thoughts this?

auscruz wrote:thanks KAM-

This is what the Trapezoid-shaped Throat Opening calculator on plantcalc.com spit out with a 1.5 bridge (math is hard glad someone else is doing !)
Top Length: 18.439
Bottom Length: 11.091
Height of cut-out: 3.5

Do you see any problems going with this ?
Looks good to me.

Also - I like the look plenums and stack what are you thoughts this?

If you are talking about what is in my cooker pic I love them.

I have a hinge question- I got a few of the weld on tier drop style of hinge - any advice on using these?

I am planing on using 1/8 flat bar for the skirt on the outside of the door and welding the hinge to the skirt-

Thanks

HI - the smoker build is coming a long -

I am thinking of using 4 inch square for the chimney- any thoughts on using square section v round? any square chimney success stories?

Also how far down the side of the chamber is standard for the a non-RF - right at the top OR even with he top rack?

Thanks

The square is fine just watch your length as the volume is more per inch. As for how far to go in I do not let my exhaust go any deeper than I need to weld out. I am not a fan of exhausts in the cook chamber I want them as high as I can get them.

Hi All, well we finished the Smoker (thanks very much for the advice) and have run it in and cooked on it a few times - I have some issues that i need advice and thoughts on-

to review here are the specs - i finished with -

Smoker

FB to CC opening

intake vent

4" box chimney


Defector and tuning plates




I came from a fairly cheap offset that I modified, that one produced great results using lump basket and the minion method. I got steady controllable heat/smoke with that one.

I have a Fire/heat controller issue with this new one - The fire I built was a lump base and I added a couple of sticks at a time through out the cook, this gave clean heat/smoke with the intake at 3/4 open and the chimney vent fully open, but the temp would quickly climb to 300+ on the FB side and the chimney side was at 200-240, also the first box looked very hot. I would then have to choke the fire down with the vents and this caused much darker not great looking smoke - it was a battle to find the sweet spot for any length of time. The turn plates were roughly as follows, deflector to 1st 3/4", 1 to 2 1.5" 2 to 3 3", and 3 to 4 4".

The best result I found was to close the intake and open FB door fairly wide, this lowered the temp some and caused much more steady and even heat/smoke flow. I think this increased flow with cool air and let some heat out of the FB at the same time. The fire was never what I thought was large, probability a 12 X 12 bed of coals and I was adding no more than 2 12 X 3-4" split sticks a time once the others had burn down considerably.

A few thoughts I have that I would like the groups opinion on-

- I feel like smoker is not drawing well - I add considering adding a chimney chamber (similar to the one in the pic below) and increasing the chimney to 6" pipe in hopes of increasing draw and evening out heat and smoke flow.


Could the FB to CC open be to small?

- Also I think I going to try the lump basket technique like this


Advice and thought on this would be greatly appreciated-

Thanks
Rob

It just dawned on that fire grate height is another factor - my grate is 3" from the bottom of the FB -

I just had a look, The bottom of the intake and fire grate are almost at the same level. It looks like to could be an issue with the fire being able create good draw?

Rob

Have you tried reducing the gaps of the plates on the firebox end to say 1/4" and increase to the exhaust side? You will need to find the best position of the plates and this could take several cooks because it also accounts for your coal base and average meat amount.