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huskerhames
Joined: 19 May 2010 Posts: 7
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Posted: May 22 2010 Post subject: Cut Out Excel SS to help find square inches on circular pit. |
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I have created a spreadsheet that will calculate a sector (area) of a cut out on a circular chamber to match the square inches on the Pit Ratio. It works slick...all you have to do is put in the degrees of an angle til you match the sqare inches of the opening needed between the firepit and cooking chamber. It is easy to calculate on a square bottom, however the circular becomes a chopped sector of a circle. The spreadsheet will give you the cross section distance and the height off of the bottom needed to the reverse flow plate or the tuning plates. I have to post it to a web site first....grrrrrr. |
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SoEzzy BBQ Super All Star

Joined: 13 Oct 2006 Posts: 13183 Location: SLC, UT
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Posted: May 22 2010 Post subject: |
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Send me a copy and I'll host the post for you.
Check your PM's _________________ Here's a change Robert.
I still work here! |
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k.a.m. BBQ Mega Star

Joined: 12 Dec 2007 Posts: 26020 Location: Southeast Texas.
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Posted: May 22 2010 Post subject: |
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huskerhames, now this could be useful. Thank You for the program. And Thank You SoEzzy for offering your services.  _________________ Always remember slow and steady wins the race.
Hybrid Cooker |
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huskerhames
Joined: 19 May 2010 Posts: 7
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Posted: May 22 2010 Post subject: Your welcome k.a.m! |
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We have used it on three smokers and i am in the process of building another. They seem to be getting bigger everytime.
Soezzy, where can i find the post of the cut out ss? Thanks again! |
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Alien BBQ BBQ All Star

Joined: 12 Jul 2005 Posts: 5426 Location: Roswell, New Mexico
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Posted: May 23 2010 Post subject: |
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Area of a circle= Pi times the radius squared. If it was 3 inches it would be....
A = Pi times r times r
A = 3.14 · (3 in) · (3 in)
A = 3.14 · (9 in)
A = 28.26 in
If you know the diameter then the radius is 1/2 as large.
If you want to figure out the cutout then just divide up the total area into sections (like 8 even sections, count how many sections fits in the desired hole and multiply the fraction by how many sections you have.) _________________ https://www.linkedin.com/in/michaeloberry |
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huskerhames
Joined: 19 May 2010 Posts: 7
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Posted: May 23 2010 Post subject: ok |
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ok alien...the ss gives you the proper height and width of the reverse flow plate. i understand your math, however, this is the area of the sector minus the are of the triangle from the plate. [/b] |
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Alien BBQ BBQ All Star

Joined: 12 Jul 2005 Posts: 5426 Location: Roswell, New Mexico
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Posted: May 24 2010 Post subject: |
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I hope I am understanding your question, in this example the total area of the circle has been divided into 4 sections so the opening (because it takes up 1/4 of the total sections) is 1/4 of the total area. In the case of the 3 inch circle I used before the area of the opening is 7.065...... 28.26 / 4
 _________________ https://www.linkedin.com/in/michaeloberry |
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dodis Newbie
Joined: 09 Mar 2010 Posts: 30
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Posted: May 25 2010 Post subject: |
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Huskerhames,
Finally got a chance to catch up on the forums, and wanted to get a copy of your spreadsheet so I can incorporate that into the full pit ratio calculator spreadsheet. I'll PM you with my email address.
I can see a couple of uses for a sector calculation, as you described, and also to calculate the opening sizes for a round firebox air inlet with an adjustable cover.
I was also thinking before of using a chord calculation to compute the offset value for someone building a round smoker with round firebox, to calculate how much to offset the two pipes to create a firebox to cook chamber opening of the correct size.
I am referencing this thread in the sticky thread for the pit ratio calculator to tie these calculations together.
Mike "Dodis" _________________ Mike "Dodis"
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UDS (55 gal & converted Old Smokey Electric)
Weber One-Touch
Broil-King Baron
Red"neck"stone Griddle |
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SoEzzy BBQ Super All Star

Joined: 13 Oct 2006 Posts: 13183 Location: SLC, UT
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huskerhames
Joined: 19 May 2010 Posts: 7
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Posted: May 25 2010 Post subject: cut out |
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alien, here is the sector minus the triangle.
[url]http://i904.photobucket.com/albums/ac244/huskerhames/cutout.jpg
[/url] |
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Alien BBQ BBQ All Star

Joined: 12 Jul 2005 Posts: 5426 Location: Roswell, New Mexico
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Posted: May 25 2010 Post subject: |
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Okay, now this will get you real close but not an exact number.
1/2 of "A" = radius
"C" will = 1/2 of total area of circle.
Just to stir the pot, have you factored in eddy currents and flow dynamics? _________________ https://www.linkedin.com/in/michaeloberry |
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