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Does the lower egg half expand when hot?

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speed51133
speed51133 Posts: 691
in EggHead Forum
I am cutting a hole in a table for the egg. The table is concrete. Does anyone know if the bottom half of the egg expands when hot? Any idea how much?
XL BGE and Kamado Joe Jr.
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  • SonVolt
    SonVolt Posts: 3,314
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    I would leave a 1/2" air gap regardless. 
    South of Nashville  -  BGE XL  -  Alfresco 42" ALXE  -  Alfresco Versa Burner  - Sunbeam Microwave 
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  • speed51133
    speed51133 Posts: 691
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    All around it??  That seems excessive
    XL BGE and Kamado Joe Jr.
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  • RRP
    RRP Posts: 25,888
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    speed51133 said:
    I am cutting a hole in a table for the egg. The table is concrete. Does anyone know if the bottom half of the egg expands when hot? Any idea how much?
    I highly doubt any ceramic that has already been fired and glazed can expand! Now, a cast iron skillet, or cast iron Dutch oven? Sure! but a ceramic BGE base...NO WAY! that's the reason it is fired ceramic!

    Re-gasketing America one yard at a time.
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  • caliking
    caliking Posts: 18,731
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    RRP said:
    speed51133 said:
    I am cutting a hole in a table for the egg. The table is concrete. Does anyone know if the bottom half of the egg expands when hot? Any idea how much?
    I highly doubt any ceramic that has already been fired and glazed can expand! Now, a cast iron skillet, or cast iron Dutch oven? Sure! but a ceramic BGE base...NO WAY! that's the reason it is fired ceramic!

     There was the case of the old mini eggs with the ring stand. There were some pics of minis neatly circumscribed  where the ring stand hit the base. And the bottom of the mini fell off. 

    I vote for an air gap, if you have a concrete top. I believe @NPHuskerFL has an SS top on his table, without an air gap, but SS expands differently vs concrete or ceramic. 

    #1 LBGE December 2012 • #2 SBGE February  2013 • #3 Mini May 2013
    A happy BGE family in Houston, TX.
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  • StillH2OEgger
    StillH2OEgger Posts: 3,746
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    This might be a stupid question, but is there any chance the concrete expands/contracts slightly under different conditions?
    Stillwater, MN
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  • JohnInCarolina
    JohnInCarolina Posts: 30,944
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    RRP said:
    speed51133 said:
    I am cutting a hole in a table for the egg. The table is concrete. Does anyone know if the bottom half of the egg expands when hot? Any idea how much?
    I highly doubt any ceramic that has already been fired and glazed can expand! Now, a cast iron skillet, or cast iron Dutch oven? Sure! but a ceramic BGE base...NO WAY! that's the reason it is fired ceramic!

    The Big Green Egg company itself says that it expands Ron, just less than other ceramics.  
    Most ceramics, even fired ones, have positive CTEs.  

    Of course the concrete will expand too as it heats, so you have some wiggle room there.

    Anyway, a 1/2” gap sounds reasonable to me.  Mind the gap.
    "I've made a note never to piss you two off." - Stike
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  • JohnInCarolina
    JohnInCarolina Posts: 30,944
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    StillH2OEgger said:
    This might be a stupid question, but is there any chance the concrete expands/contracts slightly under different conditions?
    Not stupid at all.  I’m assuming you’re talking about moisture and humidity, and without question those can influence CTEs.  The effects tend to be pretty minor for most materials like these, but they’re there.
    "I've made a note never to piss you two off." - Stike
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  • Carolina Q
    Carolina Q Posts: 14,831
    edited May 2020
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    Does it expand? Of course it does...


    I hate it when I go to the kitchen for food and all I find are ingredients!                                                                                                                                                                                                                           

    Michael 
    Central Connecticut 

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  • Photo Egg
    Photo Egg Posts: 12,110
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    Carolina Q said:
    Does it expand? Of course it does...


    I think it was the extreme cold outside temp that shrunk the stand.
    Thank you,
    Darian

    Galveston Texas
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  • lousubcap
    lousubcap Posts: 32,336
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    JohnInCarolina said:
    Gents the cracks that form in just about everyone’s BGE are evidence that they expand while heated.  The expansion isn’t uniform in the radial direction which gives rise to large tensile stresses and thus, fracture.  
    Fracture mechanics at its best on the forum.  You could learn a lot here... B)
    Louisville; Rolling smoke in the neighbourhood. # 38 for the win.  Life is too short for light/lite beer!  Seems I'm livin in a transitional period.
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  • Gulfcoastguy
    Gulfcoastguy Posts: 6,296
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    StillH2OEgger said:
    This might be a stupid question, but is there any chance the concrete expands/contracts slightly under different conditions?
    Nothing stupid about it at all. Concrete expand when hot and contracts when cold, that is why concrete roads and bridges have joints.
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  • RRP
    RRP Posts: 25,888
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    Please excuse my stupidity. Heated metal expands but I just never knew that fired ceramics do as well! Nice to learn something new every day, huh? 
    Re-gasketing America one yard at a time.
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  • speed51133
    speed51133 Posts: 691
    edited May 2020
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    The thermal coefficient of expansion for stainless is 18cm x 10 to the-6 per degree C of temperature Delta  per meter of length. For ceramics it really depends on the type of ceramic. A typical CTE of fired stoneware is anywhere from 2in to about 6in. 

    Following the mothership recommendation the cutout should be 26.25in when the egg it's dropped).down 12.5 in in the table. At that height, the diameter of the egg is 26in ( i  measured). That is an air gap all around of an eighth in.

    No idea what kind of ceramic the egg uses, but a half inch of gap all around is way Overkill in my opinion. 
    XL BGE and Kamado Joe Jr.
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  • JohnInCarolina
    JohnInCarolina Posts: 30,944
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    Well maybe split the difference and go with 1/4”.

    I’m reminded of the old story of a pilot and co-pilot flying and approaching a mountain range. They can’t agree on the height of the range.  The pilot thinks it’s 14,000 ft, and the co-pilot thinks it’s 18,000 ft.  So the pilot says, well, since we aren’t sure, let’s just split the difference and fly at 16,000 ft.
    "I've made a note never to piss you two off." - Stike
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  • alaskanassasin
    alaskanassasin Posts: 7,647
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    JohnInCarolina said:
    Well maybe split the difference and go with 1/4”.

    I’m reminded of the old story of a pilot and co-pilot flying and approaching a mountain range. They can’t agree on the height of the range.  The pilot thinks it’s 14,000 ft, and the co-pilot thinks it’s 18,000 ft.  So the pilot says, well, since we aren’t sure, let’s just split the difference and fly at 16,000 ft.
     Black box recording?
    South of Columbus, Ohio.


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  • JohnInCarolina
    JohnInCarolina Posts: 30,944
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    alaskanassasin said:
    JohnInCarolina said:
    Well maybe split the difference and go with 1/4”.

    I’m reminded of the old story of a pilot and co-pilot flying and approaching a mountain range. They can’t agree on the height of the range.  The pilot thinks it’s 14,000 ft, and the co-pilot thinks it’s 18,000 ft.  So the pilot says, well, since we aren’t sure, let’s just split the difference and fly at 16,000 ft.
     Black box recording?
    How did you guess?  ;)
    "I've made a note never to piss you two off." - Stike
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  • Legume
    Legume Posts: 14,611
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    It sounds like you have (and have had) the answer you want.  Your expertise on this sounds more than ample to counter the peanut gallery.  Keep the hole small so the gerbil food doesn’t spill down between the egg and the concrete top, that would be a mess to have to clean up all the time.
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  • NPHuskerFL
    NPHuskerFL Posts: 17,629
    edited May 2020
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    @caliking actually I do have a gap between the egg and the SS tabletop.  However, it's sealed with a high temp clear flexible silicone.  I originally sealed it to lessen movement of the egg  when rolling it around etc.  I never really move it about so.... But, it does make for an easy cleanup on the table surface. The outer edge on the table top around the egg do get hot during high heat situations.  
    LBGE 2013 & MM 2014
    Die Hard HUSKER & BRONCO FAN
    Flying Low & Slow in "Da Burg" FL
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  • speed51133
    speed51133 Posts: 691
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    I only have the answer now because I spent about an hour researching and crunching numbers. I was trying to avoid that, but thanks to all for any input. I had never really seen it discussed, only air gaps UNDER the egg.
    XL BGE and Kamado Joe Jr.
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  • alaskanassasin
    alaskanassasin Posts: 7,647
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    I know that’s right 
    South of Columbus, Ohio.


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  • speed51133
    speed51133 Posts: 691
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    thanks for the flag :open_mouth:
    XL BGE and Kamado Joe Jr.
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  • JohnInCarolina
    JohnInCarolina Posts: 30,944
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    speed51133 said:
    thanks for the flag :open_mouth:
    LMAO welcome to my world man!   Wasn't me by the way.  That post seems fairly innocuous to me, I don't know why it would be flagged.  But then just about anything gets flagged these days by the anonymous cowards. 

    Anyway, good luck with the table.  You probably realized this already, but if you find that the gap you put in isn't quite large enough, you can always raise up the egg a little bit (with a spacer or the little nest thing) to give you a little more clearance.  
    "I've made a note never to piss you two off." - Stike
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  • brentm
    brentm Posts: 422
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    They should make a flag like... "Solved" so you could mark your thread as solved.

    But I think here, flags have little meaning in life.  In fact, I've been told they do not exist.
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  • alaskanassasin
    alaskanassasin Posts: 7,647
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    This was a much friendlier place before the anonymous flag function 
    South of Columbus, Ohio.


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  • Legume
    Legume Posts: 14,611
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    alaskanassasin said:
    This was a much friendlier place before the anonymous fl
    ag function 
    Like the zoom function, this too may be @Botch’s fault.
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  • alaskanassasin
    alaskanassasin Posts: 7,647
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    I’m just glad @botch lives 2,000 miles away because he too may expand when he gets hot.
    South of Columbus, Ohio.


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  • caliking
    caliking Posts: 18,731
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    speed51133 said:
    I only have the answer now because I spent about an hour researching and crunching numbers. I was trying to avoid that, but thanks to all for any input. I had never really seen it discussed, only air gaps UNDER the egg.
    Where's the fun in that? =) Its much more entertaining this way! (And the question usually gets answered. Eventually).

    #1 LBGE December 2012 • #2 SBGE February  2013 • #3 Mini May 2013
    A happy BGE family in Houston, TX.
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  • Smolder
    Smolder Posts: 104
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    I would think that if the egg is expanding/contracting, there would be cracks in the glaze. I've had my egg for 25 yrs and the glaze looks like the day I bought it.
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