K79 Oven Build

[boerwarrior]

Re: K79 Oven Build

The FB Plans (version 2) state this:

Day 1. Maintain a fire temperature of 300?F throughout the
day and as long as possible into the evening. If you cannot
continually run a 300?F for at least six hours, repeat step 1
for a second day before moving on to Day 2.

But I would go with David S's suggestion. I don't think it hurts to be very conservative when curing!

[david s]

Re: K79 Oven Build

Saying maintain a 300F temp is a bit misleading, because it depends on how you are measuring the temp and where you are taking the readings. An IR will only give you the surface temp and the crown of the dome will be way hotter than the walls at base. Likewise an air temp thermometer will read lower at floor level. I prefer to use an air temp thermometer at floor level. Try to avoid flame impingement on the dome for early fires.

[Gulf]

Re: K79 Oven Build

An alternative, which I don't think is in the curing section would be KD's Heat Bead method. That would be" charcoal" here in the states. I used a blast/smoking door with thermometer and a damper in the flu/U][/B] to help control the temps. I think that partially restricting and adjusting the exit of the flu with some temporary placement of brick or other non combustible would work for those who do not have a damper. It takes a little work, but it keeps the danger of direct flame impingement, uneven heating,and the natural urge to ramp up the fire , to a minimum .

[david s]

Re: K79 Oven Build

Yes, I totally agree Gulf. I've been using heat beads for years because they don't flame up like wood to give you that out of control fire. Use some small wood in addition to the heat beads. For some reason FB state that their warranty is void if owners use coal or charcoal, maybe too hot. The heat beads in Australia are made from brown coal and I think burn a bit more gently. Brickettes is another name for this fuel.
I've built close on 100 ovens so have driven the water out of plenty. Just when the thing starts to dry a bit, so does the fire want to start raging. Be careful this is a danger point. Go slow until that persistent ring of black around the base disappears.

There is another method I sometimes use which is safer for the oven, but potentially more dangerous for the operator, however we are banned from discussing it.

[Gulf]

Re: K79 Oven Build

Thank's David,
The Heat Bead Method does work great! And to coin a term from my "oil patch" years is "worm proof" (worm is = but not greater than novice )
About the latter mentioned method. I had the equipment and the means to try this. But, not all of the safety features, nor the blls try it

[boerwarrior]

Re: K79 Oven Build

You've got us newbies curious now - you're going have to tell us what the curing method is " that shall not be discussed" !!

[K79]

Re: K79 Oven Build

Anchor plate is on. Bolted down and mortar on.

[K79]

Re: K79 Oven Build

Is the chicken wire used to hold down the fiber blanket just there to keep it in place while the enclosure is built or is it there to keep it tight up against the dome. I'll be burrying my dome and fiber blanket in vermiculite once the enclosure is built.

[Gulf]

Re: K79 Oven Build

Is the chicken wire used to hold down the fiber blanket just there to keep it in place while the enclosure is built or is it there to keep it tight up against the dome. I'll be burrying my dome and fiber blanket in vermiculite once the enclosure is built.

From my experience the fiber blanket seems to hold firm and stay in place where it is placed. I included chicken wire on my dome in hopes of keeping some of the weight of the vermicrete from compressing the blanket. If you are back filling with dry vermiculite, it may not be needed.

[stonecutter]

Re: K79 Oven Build

Is the chicken wire used to hold down the fiber blanket just there to keep it in place while the enclosure is built or is it there to keep it tight up against the dome. I'll be burrying my dome and fiber blanket in vermiculite once the enclosure is built.

No biggie if it doesn't contact the dome completely...air space is a good insulator.

[K79]

Re: K79 Oven Build

Starting to come up with my decorative arch design. The stone in this picture is what my wife and I picked out. I'm thinking of making the decorative arch out of standard brick with the keystone being a piece of granite with an L engraved in it. Something like this photo.

[K79]

Re: K79 Oven Build

Ok so I've been reading the past few days on the curing fires. I'm going to put in a few 500 watt halogen lamps. My question is... and I find all kinds of answers on here is... do I hold my first fire and those following once i hit my desired temp for 6 or so hours (some say the first two fires hold for 12 hours or more) or do I drop down to ambient temp once I hit my high for the day?

[GIANLUCA]

Re: K79 Oven Build

That's cool!! I like it

[fabby]

Re: K79 Oven Build

I am no expert, but I had some really low and long fires for the first three or four curings. Probably in the 3-5 h range. I did let the first fires die out several times so that the temp would not get to high. I was using a grill thermometer to monitor the temp, as I did not have my IR laser thermometer at the time. By my fourth fire, temp was approaching 400f.

My overall advise, take you time, go low and slow. Don't rush. From all the experts on this great forum, I followed there advise and I have yet to see any cracks in my 42". (knock on wood). The only other note, I had to wait at least an additional two weeks after I finished the dome to start any fires as I was out of town. This probably had something to do with drying things out as well because the daytime temps were above 75F as well. The longer your mortar cures, the stronger.

[K79]

Re: K79 Oven Build

Ok all my CF blanket is on and I'm ready to start curing. I'm using 2: 700 Watt Halogen lamps for my first few curings. I tried it for 15 minutes tonight just so I could see light from the inside of my oven. I'll start them up for longer tomorrow. In 15 minutes I had my floor at 85 F and my walls towards the top of my oven at 125F. I wonder how hot these lamps will take me??? I'm using a MT6 laser thermometer.