Hi all from Aussie

[Aussie Pete]

Re: Hi all from Aussie

Does anyone see any problem with attaching my steel bracket for my damper out of the refractory cement?. What will or should i do to help stop it from cracking around the steel, i need it to sit in there nice and snug, so it really needs to be mortared in. Will the refractory cement expand and crack around the steel, would this even be a problem, as long as it doesnt fall out i suppose.
Also, is it possible to determine how much steel will expand, the thicker the steel, the less it will expand?. Just trying to work out how much gap i will need in the slide, so it doesnt get stuck.
thanks all.
build still going.....slow, but still going.

[Aussie Pete]

Re: Hi all from Aussie

been a while, but i'm still here..
haven't done much, with life and all..
i have an idea with my flue/damper transition, it might be a bit hard to describe to ya all, but i'll give it a shot.

What i was going to do is make a channel out of steel on each side of the vent exit (on top of the dome), so it looks like a "C" channel, i'll mortar that in with more refractory cement to hold into place and i will make a slide plate out of 10mm steel that will slide inside each of the channels i've made...(you still with me..)
I will silicon or attach somehow some calc. silic board on top (25mm) of the 10mm plate steel, to help hold the heat in the oven. I will weld a handle on the front of the slide to slide in/out.
Once i've made the plate/slide i will then form more refractory over the top of the plate to let my flue sit in on.
So...what do you think of that idea, its about the best i can come up with, thats pretty easy and should be able to hold the heat in (as long as i make it a nice tight fit).
thoughts anyone??

I've tried to draw something like i'm planning...its only in paint, but its sort of the idea anyway

also..do you think it would be ok to grout/render between the bricks at the front of the arch in normal grout or refractory cement?.

[Aussie Pete]

Re: Hi all from Aussie

Gulf..i have some pics for u, i read your post, and reminded me to go take some..

Al...much appreciated for your responses, as always..

Oh yeh, i cleaned out the front arch bricks (the mortar between them), i used a grinder very gently, so i can grout them better later, would it be ok to use normal grout on the front of the arch brick, or should i continue to use the refractory cement?

I also layed another strip of refractory cement over the cracks where it meets the top of the arch bricks, i'm hoping is gotta help somehow...

heres some pics so far

[Gulf]

Re: Hi all from Aussie

well...i've taken all the sand out, looks pretty good inside, i forget to keep taking pics.

Please post some. My son and daughter-n-law are thinking about a cast. Would love to have the pics to help them decide.

[david s]

Re: Hi all from Aussie

A dense fire brick is heavy and awkward to handle especially when hot. An insulating fire brick is lighter and cooler to handle but it wears easily especially as you are frequently sliding it in and out. I think a piece of kiln shelf is a much better solution, you should be able to get some from a local potter. They often have broken shelves or some with glaze runs that can be ground off. The pic attached shows the damper on my kiln. You need to wrap the shelf neatly in a couple of layers of heavy plastic so it can be removed easily and leave you with a nice sliding fit.

[brickie in oz]

Re: Hi all from Aussie

I've decided i might do a damper similar to 'Brickies' oven, with a removal/slide brick to block off when needed. Question...would this brick have to be firebrick with maybe some calc. silic. board attached on top (to help insulate heat downward), or could i use an insulated brick?.

You could use either, the insulating fire brick would be more durable as you slide it in and out.

Would the insulated brick cope with the fire & heat if i didnt take out the coals and the fire?.

Insulating fire bricks can be laid at the fire face of furnaces, so yes they will cope with the heat

If Brickies reads this...do you have any smoke or much heat loss around the edge of the removable brick, would it pay to wrap some insulated cloth around the edge maybe?.

I dont get any smoke coming out as the draw of the flue sucks in around the edges of the damper, there would be some heat lose as its not a tight fit.

Also whats an idea to slide the brick in & out on?, so it doesnt fall down inside the flue chamber. Maybe some smaller bricks set in a little for it to slide on.

I stuck my insulating fire bricks to a sheet of thin steel with silastic, my damper is long enough to not fall down plus when the leading edge falls into the flue the rear edge locks against the top of the slot.

[Aussie Pete]

Re: Hi all from Aussie

well...i've taken all the sand out, looks pretty good inside, i forget to keep taking pics.
the hairline crack i mentioned along the top of the arch bricks, surely it wouldn't hurt to plaster up a little more along that edge, just to help keep it tight?.
I've decided i might do a damper similar to 'Brickies' oven, with a removal/slide brick to block off when needed. Question...would this brick have to be firebrick with maybe some calc. silic. board attached on top (to help insulate heat downward), or could i use an insulated brick?. Would the insulated brick cope with the fire & heat if i didnt take out the coals and the fire?.
If Brickies reads this...do you have any smoke or much heat loss around the edge of the removable brick, would it pay to wrap some insulated cloth around the edge maybe?.

Also whats an idea to slide the brick in & out on?, so it doesnt fall down inside the flue chamber. Maybe some smaller bricks set in a little for it to slide on.
cheers all

[david s]

Re: Hi all from Aussie

If it decides to crack there, another layer over the top probably won't make much difference. I'd be leaving it for a week to dry and then proceed to curing and then applying the blanket.

[Aussie Pete]

Re: Hi all from Aussie

thanks dave, i will empty out sand tomorrow (RDO), so will clean it out. Cant wait to see what it looks like on the inside,...hope it turned out ok.
there does seem to be very small hairline cracks along the brick arch, where the refractory cement meets with the bricks of the arch...i know everyone says.."dont worry, nothing to worry about"...but its hard, should i put another thicker layer over the top, or just leave it.
it will have blanket then verm/perl over it anyway.

[david s]

Re: Hi all from Aussie

Well, its been a while, but some progress has been made, i've made the refractory dome, everything went pretty smoothly, ( with a little help from the missus). I've put plastic over the dome, has been now for about 5 days, i will take it off in a day or 2.
I'm picking up some more refractory cement on friday, with some calc. silic. board (for the door), i need some more cement for my flue transition (still not sure how exactly i'll do it), plus i need to work in the damper somehow. Any thoughts or ideas welcomed.
would it be safe to take out the sand cast now?, i want to try and put some heat lights or heat beads in there to help with the curing....(cant do it with sand in there).
I've got the blanket, then i'll be ready for the verm/perl mix.

The reaction is complete you don't need to keep it moist for longer than 24hrs. Remove the sand ASAP and try to let the weather (ha ha) dry it for a week. Don't begin to light any fires until you have finished the entry.

[david s]

Re: Hi all from Aussie

The mesh really just helps to keep the form spherical by pulling any folds in the blanket tight IMO. There is really not much point in trying to make the vermiculite layer stronger because you are trying to use it as insulation and to provide a good surface to stucco/render on to. It does give the vermicrete something to hang on to though.

[Aussie Pete]

Re: Hi all from Aussie

i've been trolling a bit for some ideas, and i come across this statement made on another thread somewhere.

"Just go with straight portland cement/perlie (or vermiculite) for the whole depth. No reinforcing. This layer will act only in compression therefore no structural benefit to reinforcing it. In addition, the pearlcrete is quite porous and the reinforcing will rust inside the layer."

My question now is.... do they just mean not to reinforce within the verm/perl mix, or any kind of reinforcing?, so do i still layer some wire mesh (chicken wire, whatever) over the blanket then put on the verm/perl mix. I always thought that you make the dome, put blanket on, then mesh over the blanket, then insulation layer.
Do you really need to mesh over the blanket?

[Aussie Pete]

Re: Hi all from Aussie

Well, its been a while, but some progress has been made, i've made the refractory dome, everything went pretty smoothly, ( with a little help from the missus). I've put plastic over the dome, has been now for about 5 days, i will take it off in a day or 2.
I'm picking up some more refractory cement on friday, with some calc. silic. board (for the door), i need some more cement for my flue transition (still not sure how exactly i'll do it), plus i need to work in the damper somehow. Any thoughts or ideas welcomed.
would it be safe to take out the sand cast now?, i want to try and put some heat lights or heat beads in there to help with the curing....(cant do it with sand in there).
I've got the blanket, then i'll be ready for the verm/perl mix.

[Aussie Pete]

Re: Hi all from Aussie

cheers dave, much appreciated.

[david s]

Re: Hi all from Aussie

Pete,
Because it's a different reaction than calcium silicate cement, you do not need to add any more moisture. I cover castings with cling wrap when finished. It sticks closely to the surface. Throw a tarp over that as well and leave for 24hrs. After a couple of hours you will feel the heat the reaction generates, just like plaster of Paris.
Dave