My Build 42" oven GT

[gtofani]

Thanks for the photos of the form for the top chains.
I just completed row 5, row 6 appears to be the last one where I have to make cuts at the arch.
I am watching the joints more closely, inserting a sliced brick once in a while to stagger the joints,looks much nicer.

[IMG][/IMG]

[benguilford]

What mortar mix did you use Laku? I used the home-brew mix listed here on the forum, mixed up to a trowellable consistency, but I found I had to wait 3-5 minutes for each brick to set enough to hold once I got to the 7th of 8th chain.

Actually, I think I have found my answer as I look at your photos - it looks like you cut all of your bricks to be tapered on all faces, such that you don't have any large mortar gaps on the outside face. That must have taken you ages!! Looks fantastic BTW. This would make a huge difference when laying the bricks, as the thin section of mortar would 'set up' almost immediately and hold, even on such a steep surface.

For myself and gtofani I don't think that method would work, as we both have/had a significant mortar gap between each adjacent brick in the chain, and between each chain on the outside face of the dome. This means there's just too much wet mortar in each joint, so when you start getting to the steep chains it takes ages for it to set and hold.

Has anybody else found this? I keep seeing people managing to build all the way to the top without using the form, and wondering how on earth they managed to do that! Would my reasoning above explain this?

[Laku]

I used high heat mortar from a Finnish brand and when the gap got too big for it, I used a mix that their in-house fireplace mason instructed to use. Would probably use home brew now if I did it all over again, but that's another story.

My bricks were tapered only between each brick of the chain, as I think it's the only seam that really affects how strong each chain will be as self standing structure (I could be wrong). Also allowed me to use the high heat mortar for the complete seam.

[gtofani]

I may try to cut the brick on the 7th chain so each is tapered on the sides.
There shouldnt be too many and the wet saw makes quick work of it. Or even every other brick could be tapered. I'll decide after I see how the 6th chain goes. I figure the chains circles get smaller as you get towards the top and that makes the larger outside gaps that have to be to fill with the mortar so tapered brick will help reduce that problem.

[Laku]

Also the brick width will get gradually smaller as the circle gets tighter. At least if you want to keep them staggered or don't want to have huge seams beneath the bricks.

ps. I cut all my bricks with angle grinder, not too hard specially if you have tile saw.

[gtofani]

I got row six done this afternoon, cool enough for a sweatshirt, not too hot to sweat and sunny, nice weather to work on the oven.
No problems with the rows sliding yet, I am now past the arch with a wedge cut out about half way through the brick over the arch to finish the row. I made the last two pieces like a keystone, they fit nicely with under a 1/4 inch of mortar.
I will try row 7 to see if I have trouble with the brick sliding, It also looks as though I should cut a taper on each brick to avoid the large joint on the outside. I am thrilled so far with the dome.[IMG][/IMG]

[benguilford]

Looking brilliant gtofani! Well done!

[gtofani]

thanks, Got another chain done tonight, row 7. I had to stick a few and use a combination of regular halves and tapered bricks to make it work.
I am happy with the results. I think I am done with the indispensible tool for placing the brick. Chain 8 will need to have the styrofoam form in place.[IMG][/IMG]

[gtofani]

An inside shot after the 7th chain.[IMG][/IMG]

[benguilford]

Looking very neat there, I see you've been cleaning your brickwork as you go. Sound plan! I failed to do that, and subsequently spent several hours scraping the mortar off with a chisel and scourer. The home-brew mix sets hard as a rock!

BTW, nice lake you have there. I aspire to have a lake just like it, is it stocked with trout?