36" Pompeii Build Redux - This Time In CA

[rsandler]

Finished course 7 during the week, and 8 today. Getting really close here, though going slower and slower. Probably jinxing myself by writing this, but so far have only had one brick fall, when I tried putting a second brick on a course (6, I think) without leaving the first brick overnight and knocked both loose. Dome calculator says it should take 10, then a plug

Starting to get my entry set up in between bricks, so as to wait for the mortar to set up a bit. Because of the unevenness of the edges of the bricks, having a bit of trouble getting reasonable seams in the floor, so resorted to ripping the edges straight with the brick saw.

[MarkJerling]

Wow! You're making fantastic progress.

[rsandler]

Got about half of course 9 done this afternoon before needing to quit to make dinner. Onr interesting thing--the newer Thermo1200 CalSil boards are supposedly water resistant. I can now really verify that. Yesterday I test-placed some bricks for my entry floor, which had been soaked in order to rip the edges straight. Today I picked them back up to work on leveling a bit with sand/clay mixture, and found that there were perfect, brick dust-infused droplets of water just sitting there on the CalSil where they'd seeped from the bricks. Pretty wild!

[rsandler]

Finished course 9 yesterday. Course 10 is looking to be a bear though. Tried putting a started brick up last night after closing course 9, but managed to knock it loose while trying to clean up mortar from the inside. Thought I managed to get it reset, but the slightest tap on it when I checked in the morning knocked it loose. Reset again this morning, but the mortar joint cracked during the day, and as soon as I removed the IT around 2:30, it fell off. I set it a third time after thoroughly wetting both the starter brick and the course below, and will go again tomorrow. Based on the calculator and my measurements, 10 courses should do it--I'll have a bit over 4" left to span with a plug. Just have to get the durn bricks to stay up!

In the meantime working on my door. Got started shaping the CalSil blocks, the wood face and the felt. Tomorrow I'll try sewing the Nomex after I get a curved sewing needle. Did a quick test with the calsil loosely wrapped in felt, and discovered that my arch is not quite as in-plane as I thought it was, so I've got some nervy angle grinder work ahead of me to even that out. Sure wish I could just take a hand plane to it like I would with wood! Also seems that the Nomex felt likes to catch on the rough surface of the firebrick landing. May need to look into something smoothing for the bottom surface; Kevlar skids, perhaps.

[rsandler]

Course 10 complete! Good thing that course was small, because man it was a pain! But it's done. Just have to cut a plug and the dome will be closed. Hurray!

Also did a bit more work on my door. Got the fabric cut and pinned, but only have put two stitches in, mostly to try out the curved upholstery needle I bought for the job.

[rsandler]

Done! (Ish; still insulation, and vent, and enclosure and...). Cut my capstone this morning and laid it this afternoon. Summoned my wife and kids out to make a little ceremony out of placing it (with obligatory sarcastic commentary from the 12yo ). Did a bit of the usual awkward cleanup, including trying to squeeze some extra mortar into my more unsightly gaps with a cheap pastry bag.

Also finished upholstering my door (that's what you do with a door, right? Upholster it?). I'm really pleased with how it's turned out so far. Despite my fairly rough stitching, the cover is tight enough that if I lift by one side, the other insulation board doesn't slide around. I suspect that if I weren't bothered by the look,* I could just sew on a couple of heavy-duty nylon straps to the outside as handles and be done with it. More importantly, despite the unevenness of the arch, the felt has enough give that it seals tight without any grinding of the bricks. Only gap I could detect is right at the bottom corners, due to the door corners being a little rounded, and there being a little gap from my thermal break. Good stuff! As long as the Nomex can stand the heat, this should be a pretty effective door.

* I'm not excited about having the plain felt surface for the door, but I was joking with my family that I could have embroidered the outside surface to make it look nicer, if I had that skill (I do not). The notion of an embroidered oven door amused us considerably

[david s]

You may find that the contracting arch will jam the door so tight that it will be really difficult to remove. I made a similar door for my first oven and had trouble with this problem. most builder/owners find a door that sits against the flat face works better than the door sitting inside the oven mouth and copes without the contraction of the mouth becoming a problem. See how it goes.

[rsandler]

david s in fact, this door sits against the flat face, largely on your recommendation. Since my arch is a touch out of plane vertically, I was really pleased that the felt-covered door still seems to make a pretty tight seal against that face.

[david s]

Ah yes, my error. Looking closer at it I can see that it doesn't sit under the oven mouth. My apologies. It will be interesting to see how it performs.

[MarkJerling]

Done! (Ish; still insulation, and vent, and enclosure and...). Cut my capstone this morning and laid it this afternoon. Summoned my wife and kids out to make a little ceremony out of placing it (with obligatory sarcastic commentary from the 12yo ).

Hahaha. The twelvie will eat his/her words when the first pizza goes onto a plate.

[rsandler]

Hahaha. The twelvie will eat his/her words when the first pizza goes onto a plate.

She's already counting the days until first pizza (I told her two weeks), so sarcasm and pizza enthusiasm aren't mutually exclusive :-)

Made pretty good time building my vent today; managed to get the whole arch put together. Rather than doing an S shape for the middle segment, I built up both sides to around 45 degrees, then placed a brick cut at 45 degrees in the center, with both the center brick and the outside bricks notched so that they'd sit together. The theory is that the middle bit is then braced on the front and back arches, and so more stable than just having mortar. The front is all higgledy piggledy, but I'm planning a decorative arch to cover it once I build the enclosure, so I didn't worry about it, and just tried to make sure it was all stable.

Curing question: the plans say to let the oven sit for a week before starting fires, but I know some builders have used a halogen light to help dry things out before starting fires. I've got a big light and also a space heater my dad leant me. Should I wait on those for the week too?

[david s]

If you used the homebrew mortar which contains Portland cement, its strength will be enhanced by damp curing for at least a week. If you used a refractory mortar containing calcium aluminate cement CAC, it can be dried 48 hrs after completion because it achieves full strength much earlier.

[rsandler]

Fair enough. Ship has sailed with respect to most of the lower courses (mortared over a week ago with nothing special done to achieve a damp cure), but I figure the top courses need strength the most. I put a couple of damp towels on top of the dome and covered the whole thing with a tarp today (already had it tarped to protect the insulation from some passing rain we've been getting). I'll start with the light on Saturday, then move on to charcoal, and then small wood fires. That'll give time for me to finish the vent transition, and for my chimney parts to arrive, having just ordered those today. Also have a delivery of firewood coming next Monday, though I may grab a small bundle from the hardware store grocery store to start the curing process--shouldn't need much for the first couple fires.

With any luck, we may get a first pizza out of this oven around the 21st, weather allowing.

[david s]

Many builders have found through bitter experience that it is far safer to insulate before starting any fires. Personally I like to allow the sun and wind to do much of the drying for a week before applying the insulation, then if a wet mix is applied over the blanket, to allow it to dry for a week before any drying fires. Obviously you're keen to finish, but hurrying at this stage can lead to tears.

[rsandler]

That was more or less my plan--I was going to put the insulation on after the light and before any live fire; not sure whether it makes sense to do that before or after a day with heat beads/charcoal. Certainly want the insulation on before going much above 200F/100C, but seems like it makes sense to leave it off at the very low end of temperatures to allow water vapor to escape more easily. Hadn't planned on separate weeks for damp curing and air drying though.

Best I can tell from my previous thread and my picture archive, on my previous oven I started curing fires with just newspaper about 6 days after laying the plug, and put the blanket insulation on around when it was time to go up to 300F. That oven never cracked on the inside, and I will forever be blissfully ignorant of any cracks on the outside :-). But I'll still wait until the weekend to put any heat in this thing.