CRACKS!!!!Stress rising

[TxTanner]

Re: CRACKS!!!!Stress rising

The interior of the oven is cast against a form so it would not be unusual nor harmful to see small void or tiny pock marks.if there is a patch it could just be a small repair.Are you saying the crack originates from the patched area?If it doesn't don't sweat it.Probably time to have another beer.....

Bill

[austinmc]

Re: CRACKS!!!!Stress rising

yes....exactly. It looked like there were patches that were repaired. You can see the outline of what looks like a patch. Not sure if that is what it is, but looks like one???

[TxTanner]

Re: CRACKS!!!!Stress rising

Ok back on track Austinmc.After rereading your post what stuck out this time is that you said you had what looks like patches.Do you mean it looks like someone tried to repair/patch the casting?

[boerwarrior]

Re: CRACKS!!!!Stress rising

Thanks Bill

I did build the shed but that was in December and January. The 16 weekends was for the pizza oven and the flagstone patio. There are over 1,000 "antique style" (but new) bricks in the oven base and structure, along with 200 or so firebrick for the oven. The patio is Arizona "Rosa" and what you see is about 500 square feet.

austinmc - many apologies for hijacking your thread!

[TxTanner]

Re: CRACKS!!!!Stress rising

Hey Warrior I'm glad you got a laugh out of it.I hope everyone here can relate to at least some part of that story I can certainly relate to your point.It's easy to
talk yourself into taking on a project at home and miscalculate the time it'll take to do it.We always say,however long you think it'll take to do it just double that and figure materials will be twice what you thought.Thanks for posting the picture.Looks like you did a great job on the design and execution.16 weekends does sound like a long time but hey that's a killer garden shed.Now if you mean you did the oven and flagstone in 4 months by yourself that's rally not bad considering all the interruptions when you work around the house.It looks really well done.The 4 arches are great and the grout lines look tight on the flag stone.Whats the dimensions on the flagstone?In Houston people charge from 16 to 24 dollars a sf for that retail.you saved yourself alot of money and still got a pro job.By the way is that reclaimed brick?

[boerwarrior]

Re: CRACKS!!!!Stress rising

By the way,

attached is a picture of what I told my wife would take a couple of weekends!! (it took 16 weekends to be exact!!)

Neil

[boerwarrior]

Re: CRACKS!!!!Stress rising

Holy crap Bill thanks for making my day!! What a great story - you had me on the floor! My cubicle neighbor here at work wants to know what I am laughing at!!

[TxTanner]

Re: CRACKS!!!!Stress rising

Hey warrior no sweat,to tell the truth I pulled that "cool 500* in one hour "number out of thin air......or as we say down here"outtamyass".It was meant as an example,but I guarantee you it could happen and probably has.Follow along and see if you could see this happening.You(meaning anyone of us)has wanted their very own pizza oven in their very own back yard for two years so one day you say to your self damn it, I work hard,I'm a good father and husband that always puts my family's needs and wishes before my own.....so I'm gonna do it,I'm buying me a pizza oven no if ands or buts about it.So now you get on the computer and find a bunch a like minded pizza nuts and start asking questions and researching everything down to the last little detail all the while saving ever dime you can to fund this new addiction.No beer no cigarettes no eating out no golfing no movies no nothing.You sell the bass boat and put the checkbook on lock down and tell the the kids the only thing you're puttin out around here is the lights.By now the urge to call James and order 56 inches of Modena2G140 heaven is unbearable but you have one last hurdle,until now this has been a private addiction....yes it's time to tell the wife.All day at work you've been planning out what to say and how to say it,hell you even had flowers sent to her at her office.As you sit down to dinner you sum up the courage to speak in spite of the fact you know how bad this may turn out.Honey I've been thinking about how you say we have no social life and we never go anywhere or visit your family or your friends and dog gone it your right .........so that's why I've decided WE'RE GONNA GET A BRAND NEW HARLEY DAVIDSON .I got it picked out already and the best part is it's on sale for $28,000 and the dealer said he'll hold it for us till tomorrow morning plus I got enough cash saved to put half down so we'll get 0% financing.Well the next 2 hours is a blurr of insults and repressed anger as well as rehashing old arguments and a general stroll down the memory lane of discontentment.It is even made clear that you are entering the early stages of the middle age crazys and no doubt will be covered shortly in tattoos.Some how in all this it's decided the money would be better spent around the house so you give in as usual and unselfishly agree that a pizza over would be a nice compromise because ya'll can now socialize and have weekly pizza parties and invite the inlaws and her friends over as well as spending quality time together fixing up the backyard.When you suggest that you'll sleep on it tonight and decide what to do in the morning about the Harley she insist that the two of you get on the internet tonight and shop for a pizza oven and lawn furniture.Well somehow that night yall decide that the modena2g140 is perfect so its ordered and paid for in full......as a matter of fact she inscist on ordering and paying for all the materials needed for the whole project tonight,all $14,000 of your Harley down payment is gone and the night ends with her sweetly kissing you good night and telling you what a wonderful husband you are for giving up your Harley.

The next day you go right to work building your stand,the work is flowing smooth and every thing is going as planned.Saturday you form and pour your slab with great precision because you've done every step a million times in your head and are prepared for everything.Sunday you lay out your block for the stand and get everything precut and notched.You dry stack it on your drive way and its perfect.....damn your good.Monday after work you rush home and remove the plastic from your slab,knock off the forms and the slab turned out great....not a bit of porosity because you vibrated and screaded it to perfection.No time to pat yourself on the back yet,you start dry stacking your block on the slab and all goes smoothly.All the vertical rebar in the slab lines up perfect with the holes in the blocks and your flying. Steele lintel fits perfectly flush and everything checks out level plum and square on the fist try so you wast no time and start mixing rapid set concrete and back filling the blocks which goes just like you planed.While the concrete sets you start screwing your precut forms together for the supporting slab and by the time the quick set kicks off your pouring your hearth slab.It's 1 am and your exhausted but oh so satisfied and for the first time you know what it feels like to be"In the zone"Tuesday starts off with alot of coffee but you make it through the day but all you can think about is insulating that slab so as soon as you get home you change and hit the wheelbarrow and knock it out and it to just falls into place with no problems.you clean up and call the trucking company to confirm delivery and low and behold it's 2 days early....can you believe your good luck.They said they can drop it off thursday morning so you spend wednsday stuccoing the stand and taking care of any little details you can to move forward and prepare for arrival day and going over your list to make sure your prepared and you are prepared because you planned your work for a year.You wake up early Thursday and call your boss and tell him your taking off work because your kids are sick, he's really understanding and shows real concern for your kids well being so when you hang up you feel guilty about lying to such a nice guy so you wake up the kids and ask them if they're sick of school which of course they say yes so you tell them they have to stay home today.Your now guilt free so you head out back and check your list one last time but everything ready and you feel you really have thought this all through.Truck shows up at 8 sharp and you unload the crate onto special cart you made so you could wheel it in the back yard by yourself but the driver wants to help so It's in place and uncrated in 10 minutes flat.You thank him and offer to make him a pizza some day but he says ....no thanks I don't care for pizza except for Domino's.Obviously he doesn't get it so you ask him to leave so you can get to work.As you start you are amazed at how easily the oven goes together.It's hard to Know if it's your skill or just that you were so prepared for this moment.With your two boys trying to help you get it all set in less than two hours and you can't belive how smoothly the whole project has gone.You can't wait to start a fire but you know you must so you spend the rest of the day cleaning up and going over your paperwork and manuals to make sure you understand everything.Over the next week you do your curing fires every evening each one bigger and bigger.Today's the big day,not only is it May 31 which is your birthday but today you'll build your first full log fire. You start early building your fire and by 8 in the morning you have a big fire going and your just thrilled because up to this point everything has been perfect,the flue draws great and not a single crack so you go in the house for a cup of coffee.As your pouring a new cup you start to let your mind wonder and then you think you hear a strange noise but you don't know what it is.....chic.....chic .....chic....so you start heading to the back door and now it's louder....chic...chic...chic....What is that?You think to yourself that's familiar.....chic ....chic .......chic.....chic....OH NO!.......chic...chic.....chi.chi.chi.chi.chi.chi. chi.chi.chi.You run out the door but its to late,your ovens in pieces,your fires out and your automatic sprinklers are working great.Damn you didn't think about those because they're programmed off through winter,they're not programm

ed to come back
on until 8 a.m. May 31 of each and every year.Yes Sir on your birthday,you set the date ten years ago when you first bought the house.


See it could happen.

Bill

[boerwarrior]

Re: CRACKS!!!!Stress rising

Doh! I totally missed that this was a cast oven. Sorry about that!

[david s]

Re: CRACKS!!!!Stress rising

I get the rapid rise in temperature if you build a big fire.... But how can a Pizza Oven possibly cool from 500 degrees to room temperature in an hour?? Even without insulation my oven would take about half a day to cool to about 200. With insulation my oven takes days to cool down. So unless I am missing something it is only the heat cycle that is going to cause problem, not the cool cycle.

A cast oven with thin walls will cool and heat faster than a brick oven, which has thick walls.. Maybe not 500 F in one hour, but if the refractory is wet, the ambient temp low, no door and some breeze over the dome, the fall in temp will be rapid.

[boerwarrior]

Re: CRACKS!!!!Stress rising

I get the rapid rise in temperature if you build a big fire.... But how can a Pizza Oven possibly cool from 500 degrees to room temperature in an hour?? Even without insulation my oven would take about half a day to cool to about 200. With insulation my oven takes days to cool down. So unless I am missing something it is only the heat cycle that is going to cause problem, not the cool cycle.

[david s]

Re: CRACKS!!!!Stress rising

I agree Txt, that's why I asked if it was cured with the blanket on or off. I believe it's not only the rapid rise and fall of the temp of the refractory that's important, but also the temperature differential between the inside surface and the outside surface which also leads to uneven expansion, stress and hence possible cracking. If the oven is heated and it's uninsulated, the ambient temperature fairly low, maybe some wind and the outside surface wet, this will be enough to hold down the temp of the outside surface lots. To be safe to the refractory the temperature riseor fall should not exceed 100C/ hr, but nobody firing a WFO does it this slowly.The highest quality refractory materials may still fail if heated or cooled too fast.

[TxTanner]

Re: CRACKS!!!!Stress rising

I build pizza ovens and outdoor kitchen for a living but I'm by no means a refractory engineer but I got a hunch that heat stress can crack an oven either by heating it to high at too fast a rate or cooling it at too fast of a rate especially considering there's still moisture in the casting.I think cooling an oven from 500* to room tempature in one hour may be as stressful as going room to 500 in one hour.A high wind or cold weather could make make this worse.Ill start a fire in them without the blanket to help release more water from the casting but I always throw a blanket on it before putting out the fire.But thats just redneck engineering and it seems to work for me.Years a go I use to weld huge gear hubs together on a sub arc machine on a huge positioner and if you don't preheat them pretty hot before welding the welds would crack from heat stress from heating to fast but by the same token If you didn't put ceramic insulation blankets over the gears as soon the welds were being made the weld would crack from cooling to fast.I belive Tscarbourgh use to or still does rep these materials(Refractory and masonary)maybe he can comment because I could be wrong as it pertains to refractory.

[austinmc]

Re: CRACKS!!!!Stress rising

hey....thanks for the feed back. feeling a LITTLE better about it all. Kind of scary when you take a boo inside the oven and see that. still going at the cure(up to 3 sticks today)if I can get me to the 800f mark, with no more worries, I think I will be good. Going to have that "cold one" and relax. Also when I looked in it, it looked like a small piece was going to "pop off" as you mentioned Les, you still think all is good?? Man, that cold one is sounding better all the time!!!!cheers all

[Les]

Re: CRACKS!!!!Stress rising

I don't mean to be the worry wart here but that doesn't look like a stress crack. I looks to me like it has the potential to "pop" off. If no one breaks a tooth when it happens no worries. Even if is does drop, your oven will perform as hoped for many years. Have a cold one...