Trouble with setback on brick courses. Need advice.

[Amac]

Re: Trouble with setback on brick courses. Need advice.

Sorry Xene I didn't mean it to be too technical - some people love Pythagoras - others wish he never existed. I'm somewhere in between, but I can't ignore a puzzle, even if I fail to solve a lot of them
What you can do instead of building a new IT is just bevel the square bit which touches the brick and just use it to measure to the top edge of the brick. Then make sure the bottom edge of your brick aligns with the top of the brick below - with no "set back" or forward. Just be aware that the IT will not lie flat on top of the brick in that case, but point up at a slight angle. The sketches shows better what I mean. The first sketch shows the setback as it is now, and the second one how to solve it with your existing IT.

Good luck in your endeavours. I like arty ovens also so looking forward to the finished article I guess you have seen this one from Frances in Switzerland
Pizza oven with mosaic | Flickr - Photo Sharing!

[Xene]

Re: Trouble with setback on brick courses. Need advice.

Thanks Amac! Your sketches make it clear (visuals are the best) - but now I'm wondering - missing that vital bit of Geometry I should probably have had before tackling this project - what happens if I only use the top of the IT to angle each brick and align each edge with the lower course, disregarding the side 'square' alignment completely? Won't that just result in a slightly lower dome? It would come out close to a half circle it seems? I mean, realistically, at this point I could put a blow-up ball in there and all these angles would be off anyway, but the oven would still get equally hot (I assume) and cook just as well if the geometry is off - right?

If I gave this thing too much thought I would talk myself out of doing it at all - so I'm tackling it a bit like everything I do - jump in and see how it comes out. My track record in general is good - and with you guys helping me when I get stuck, I have great expectations about this project as well! Thanks as always.

[Laku]

Re: Trouble with setback on brick courses. Need advice.

Here's how you can fix your IT

[deejayoh]

Re: Trouble with setback on brick courses. Need advice.

Amac's picture shows exactly what I was trying to point out as well.

So to your post - if you try to use the top of the IT to angle each brick, you will get a lower dome, which will work fine. But you will also have to shorten the IT with each course.

Better idea might be to put a shim at the back of the flat part of your IT (the part that touches the top of the brick) that is equal to half of the height you are tilting each brick. That way, your measurement is set and constant. So if you've been tilting each brick 1/2" at the back - put a quarter inch shim in there and the angle will be right. The next brick will still need to be tilted up 1/2" inch but the top angle will be correct.

Edit: The approach in Laku's drawing would work also - as long as the long part of the IT hits the brick dead center and the brick is square (e.g. you haven't cut an angle at the top or bottom). Then it will be on the correct angle.

(BTW, I wish I had seen a conversation like this before I built my dome. It would have saved me a lot of time in sketchup and reviewing geometry...)

[Amac]

Re: Trouble with setback on brick courses. Need advice.

what happens if I only use the top of the IT to angle each brick and align each edge with the lower course, disregarding the side 'square' alignment completely? Won't that just result in a slightly lower dome?

Yep - and a slightly lower dome is generally regarded as good - and don't worry - even with the "setback" the oven will be fine. I like Laku's fix though, and it is also simple to apply to your IT.

@DJO

So to your post - if you try to use the top of the IT to angle each brick, you will get a lower dome, which will work fine. But you will also have to shorten the IT with each course.

True if Xene uses the same IT - but a simpler single piece IT wouldn't need shortening. I guess it depends on the dome height you are aiming for.

[Xene]

Re: Trouble with setback on brick courses. Need advice.

Well I got whipped by gravity today. This fifth course is where my arch falls, I battled getting the bricks cut and set the first part of the afternoon and then tried to finish the course just set in place with mortar but they kept sliding off.

SO - I'm seeing more clearly why following a scientific, totally geeky, technical method would be preferred.

I had hoped to make it higher without a form, and after setting all that up with my IT yesterday I'm not too thrilled with abandoning it already. (The fix to the IT posted by Laku looks great - thanks)

So now I'm looking for tricks to keep these bricks on the course long enough to set up so I can firmly mortar them in. Today I nearly pulled my hair out with them falling to the floor.

AND as a bonus (?)- I can't reach the top anymore, I've already got a layer of cement block all around the base to stand on, but I'm really short and now I need taller - I've done the last two course from inside so I could reach - what tricks have you used/seen for reaching the top of the oven?

Thanx

[Gulf]

Re: Trouble with setback on brick courses. Need advice.

You may need to cut some sticks to place under a newly placed brick. I found that starting from the back of the dome to the front gave me two sides to work at the same time. I would place one brick with the UT on the left and carefully slide a precut stick in it's place as I removed the UT. I would then place a brick on the other side while that one set.
I am sorry that I can't offer a pic but, I got this idea from this site. Maybe some one can link a pic and the source. As for as scaffolding is conserned, I'm a little bench legged my self . I have had to stack 2 blocks on top of each other to get the height that I needed. You might want to invest in some short 2X8" lumber to use as scaffold boards. That would allow you to use less blocks to suround the oven. But, there are kits at most building supplys that will allow you to build sturdy saw horses.
Before this build is over you might even decide to rent a set of scaffold bucks.

[deejayoh]

Re: Trouble with setback on brick courses. Need advice.

What kind of mortar are you using? My experience with the home brew is that if you mixed it the right consistency - you can build the whole dome with no forms or supports. I managed to go all the way to the final row without using anything to hold the bricks except my hand for the half or minute or so it took them to grab hold. This is the first thing I have ever built with mortar, so trust me it is not experience talking!

Couple tips: don't over wet the brick you are placing. Makes them slip off. Dip it, let the water soak in for a few secs. Mortar should be like soft mashed potatoes. Butter the brick, put a good slug of mortar in your spot and kinda twist it in there. They should stick at least up to 70 degrees, no problem

On the place to work - may not be best practice, but I just put my feet inside and sat on the opposite edge of the dome. Worked up until the last few courses.

[Xene]

Re: Trouble with setback on brick courses. Need advice.

Thanks @deejayoh, I've probably not been using enough mortar. I should probably mix up twice what I have been and really slather it on - I suspect I've been too conservative up to this point. And I haven't been getting the bricks wet, as it seemed that some said it didn't matter...although yesterday I did try getting them wet too. About 7 of them slipped off one after the other as I was nearly all the way around and then I started throwing things.

You are brave to sit on the edge! Last week I was on soldier course, so my build it moving right along, which means the last course is not fully dry before I'm laying the next. I don't weigh that much, but I really don't have the confidence to sit on it! Seems like I'll have to work from the inside a bit longer which is not very comfortable - but I could probably figure out a better system for at least a few more courses.

My oven is 46-inches, so I have a bit of room inside yet. I"m going to give it another honest effort before I resort to a form, I'm tenacious (or stubborn?) that way - really appreciate all the tips!

[Xene]

Re: Trouble with setback on brick courses. Need advice.

You may need to cut some sticks to place under a newly placed brick. I found that starting from the back of the dome to the front gave me two sides to work at the same time. I would place one brick with the UT on the left and carefully slide a precut stick in it's place as I removed the UT. I would then place a brick on the other side while that one set.

I tried sticks yesterday and I did get the brick to set in over the arch, but it fought me like no other! I'm trying to picture how I could manage the IT if I also have sticks/boards/supports up there wedged in around the brick. Ugh, was hoping for some magical method (HA) that I hadn't stumbled upon.

The scaffolding idea is probably a good one, but even at that, doing the math on the radius of the oven and my height of just over 5', this is going to be a challenge no matter how high up I can get myself -- so now I think the real 'fun' begins.

[Laku]

Re: Trouble with setback on brick courses. Need advice.

Let the first few bricks dry with the IT holding them for about 3-5 minutes (and use stick from beneath when you move to next brick). here's a picture and explanation of what I meant

[deejayoh]

Re: Trouble with setback on brick courses. Need advice.

Another thing that helps is if you have one brick that is in firmly on the course that you are able to work from. The tension from the bottom of the brick is sometimes not enough to hold it - but if you have the tension of the bottom + the side, the brick will stick.

But at the angle you appear to be working, it doesnt seem like you should have that much of a problem with the bricks sliding off. Try mixing the mortar just a little less runny.

Also - I found it much easier to work from the inside while sitting on a stool. It was only on the top few courses that I started sitting on the edge because I am not such a short person . I wasn't worried about the bricks coming off because I worked pretty slow. One course had usually dried for a day or more before I got to the next one. But I did find that the dome was strong enough to stand on even partly finished after just a couple days drying. Not sure why I felt the need to test that. But I did

[Amac]

Re: Trouble with setback on brick courses. Need advice.

Another thing that helps is if you have one brick that is in firmly on the course that you are able to work from. The tension from the bottom of the brick is sometimes not enough to hold it - but if you have the tension of the bottom + the side, the brick will stick.

This is exactly right - just one thing to add - the last brick you lay should be the first one on the next course, and let it set overnight or longer.

If the first brick is on freshly the sideways pressure on the second one will often disturb the first brick and you have to repeat the process. Happened me a few times

[Xene]

Re: Trouble with setback on brick courses. Need advice.

Okay, yesterday was a cold, wet, rainy day - a much needed rain and subsequent break from this oven build - so today I'm feeling re-fueled to give it another go. I have a better idea of where I was going wrong thanks to you guys and I'm feeling confident I have a better handle on the technique I should be using. I will be back with an update and maybe a picture of my progress. Thanks all!

[Xene]

Re: Trouble with setback on brick courses. Need advice.

I didn't get a chance to reply Friday, but I got up to course 8 on without hardly any headaches using all your tips and tricks. Thanks a million. I applied every bit of advice you all offered and didn't even need to resort to sticks. My height is still an issue and now the thing is so big I can't easily step in and out of it anymore, so I've to to rig up some hoist or something I think - a step stool, ladder, scaffolding...that will be the next thing to overcome. Short of crawling in and out of the door, I'm not going to be able to get over those newly laid courses as it gets taller. But thanks a million!