Colorado oven

[drseward]

Re: Colorado oven

I appreciate all the comments.

So, far I am resisting the urge to rush things at this point--although your comment, Christo, about your cooking pizza at this stage didn't help . I really want to get the curing thing done right. The curing protocol on this site doesn't make a lot of sense to me. Neither does the resignation that a cracked dome is a normal outcome. Perhaps I am being too naive, but I'd like to think I can avoid a crack if I do the curing correctly.

I have a number of problems with the recommending curing schedule. I have no experience with this--I am just thinking through the physics of it. I may be completely off, but here is my take. I think the first couple of days of lighting a couple of sticks of wood and then letting the oven cool immediately is doing virtually nothing when you consider the energy input in relation to the large thermal mass of the oven. I think the object should be drive out all of the moisture before the oven is taken over a couple of hundred degrees F. Perhaps that is not realistic in practice, but the recommended curing schedule can't do this.

I see two potential problems. First, the formation of steam could damage the structure. Second is the temperature differential that would exist in an oven mass heated above the boiling point of water with water still present. For instance, dry areas of the oven could heat up to many hundred degrees F while areas with retained moisture could not exceed the boiling point of water. That could create significant thermal stresses to the structure.

I think the recommended protocol is sound in intent, but falls short in actual practice. But, I am saying that as someone who has yet to cure his own oven, so take it for what it's worth.

This is the approach I'm taking (until I change my mind). I am holding the air temperature inside the oven at 190 F until the temperature of the outside of the dome under the insulation approaches the oven air temperature. That should indicate that the moisture is mostly gone. Only then will I take the oven up beyond the 197F which is the BP of water at my altitude.

I bought a cheap ceramic heater ($18) with a 1500 watt element and rewired it to bypass the thermostat and to wire the fan independently. I have the fan going constantly and the heating element switched with a PID controller. It is holding the air temp in the oven steady within 1 degree F and having no trouble maintaining this temp. At this point (two days into it) the outside of the dome is up to about 160F and slowly increasing over time.

That is a bit much for one post, so I'd better shut up now. I'd appreciate any feedback on my ideas.

Best,

Mark

[christo]

Re: Colorado oven

Nice Job for sure! I like the cast transistion - after making mine - I swore if I ever had to do it again I would cast it.

I was tasting pizza when I got to that stage, I bet you can't wait! Take it low and slow on the curing.

Christo

[Dino_Pizza]

Re: Colorado oven

Great job Mark! I think a 42" dome that's 19" in the middle is perfection. Your jig you made to form the elipse to get you there is a great idea. I love the location of your oven in the trees too. Your vent transition looks good and I assume you're installing an 8" duratech since you've got the anchor plate in. With your cast transition and deep landing, it should draw smoke very well. Can't wait to see the finished oven.

[DrakeRemoray]

Re: Colorado oven

Wow looking great!

[drseward]

Re: Colorado oven

Here are some updated photos.

I poured in place a vent transtion in castable refractory. I used a simple luan jig to imbed 4 stainless steel bolts in the proper alignment to fasten the DuraTech anchor plate.

Mark

[Mitchamus]

Re: Colorado oven

beautiful!!!

[fxpose]

Re: Colorado oven

Wow....talk about precision. Nicely formed dome, and I love the the way you capped it off.
Thanks for posting!

[drseward]

Re: Colorado oven

Here is the dome at the 11th course and after it was closed completely. As a consequence of offsetting my tool axis, it was better for me to close the top with a flat bottomed plug rather than continuing with the curve of the dome.

This technique allowed my to compensate for the thickness of the protective plywood on the floor as well as the height of jig base and still lower the dome height below the radius of the oven base--all without any changes to the jig for the entire build. In my case the oven base is 42" and the dome height ended up as planned at 19".

[Neil2]

Re: Colorado oven

Offsetting the axis like that means you have produced a shape close to an ellipse.

Very clever.

[drseward]

Re: Colorado oven

Thanks fxpose. I used the same jig all the way to the top without any changes. I finished closing the dome a few days ago and am now finishing the entry. I'm happy with how the jig worked

I'll take some more photos soon so you can see how I closed the dome. The options for closing the dome change a little by offsetting the one axis (does that make sense?). Eleven courses left me with a 10 inch diameter opening at top that I closed as you can see in a future photo that I will post.

Mark

[fxpose]

Re: Colorado oven

Very nice work! Did you use a different jig to finish aligning the rest of the courses?

Funny, I thought of this very same idea just yesterday and was wondering if anyone else had done this. It obviously worked well for you so I'll most likely be using this exact same method.

Thank you!

[Mitchamus]

Re: Colorado oven

nice brickwork!

[drseward]

I am not sure if this variation of the "indispensible tool" has been used before. I offset the second rotational axis so I could determine the oven diameter separately from the dome height. In my case the oven diameter is 42" and the dome height will be 19". With this solution I don't have to make any changes in the length of the arm with each course in order to lower the dome height.

I'm on the 7th course above the soldiers and it is working well so far.

Mark