39 inch Corner Build

[Gulf]

That looks great! JR.

[UtahBeehiver]

Yep, you got it. Inner face looks good and much better than a large inner mortar joint. You can fine tune getting back to round on the next few courses. It get easier until the plug area then back to lots of custom cuts and grinding. Great job.

[JRPizza]

I've been thinking about where my droop came from, as knowing the cause might help future builders. If I knew why droop happens, not just "avoid droop", I might have been able to prevent it.

The first graphic attached I "borrowed" from member jmargush. It was intended to show how the inverted vertical vee gets worse as higher and higher courses are laid, but you can also see how the intersection of each horizontal brick forms a slight but increasing horizontal angle that also gets greater as higher and higher courses are laid. My droop problem, and I suspect the majority of droop others have, comes from the way I laid the bricks that next to the arch. In trying to minimize internal gaps, most bricks are laid with the inside/bottom edge sitting on the brick or bricks below it. This minimizes the horizontal gaps, maximizes structural integrity, and keeps most of the bricks level and with increasing angles between them as you build up. The bricks next to the arch however sit on the brick below it that has no slope. These bricks become a horizontal stack because there has not been successive angling by the bricks adjacent and below (see second illustration). One fix (probably the easiest) for this is to compromise inner edge contact for the bricks next to the arch and artificially angle the brick upward on the arch side using a wedge of mortar to raise the bottom edge, or to cut the brick so it "rides" on the arch brick creating the angle and leaving a gap below to be filled by mortar (illustrated by dashed lines). You could use a method similar to what Gulf showed in post #14 to make sure you were making adequate compensation. I didn't do that because I didn't see the droop coming and didn't understand why it would occur.

I searched the forums for explanations of the cause of droop and could not find any. If the experts on this forum think my reasoning is sound and the explanation could help, I would be willing to start a thread in the tips forum on droop avoidance and we could all chime in and provide some good guidance. If you think I'm off base or this has been covered let me know.

[UtahBeehiver]

Should be an interesting thread. What you say about the invert V may be correct if one does not bevel the bricks. By beveling the bricks the bottom edge should be on a horizontal plane assuming the previous brick edge is horizontal. In any case, this would be a good thread, a couple other items that may be droop variables are whether the pivot point is right at the hearth floor plane (some ITs are above the floor plane), how the arch form is placed relative to the ID of the dome, whether the centerline of the IT rod/bracket are on the center of the brick, changing on the tilt of the brick for whatever reason. It just makes my head hurt thinking about it. I am retired from the Engineering business and now just do SWMBO projects. LOL.

[Gulf]

I'll let ya'll pie-r-square the causes . But, if ya'll don't want to get a headache, just find a way to keep the dome brick the same distance from the center of the oven and keep em' level . Hendo's IT works real well for one, and Colin's attachment to the IT works pretty good for the other lol.

[JRPizza]

Makes my head hurt too - took me a while to write what I did and I am not sure it is intelligible. I'm beveling my bricks, so with or without the inverted vee, the tops of the bricks are at an angle where they intersect. That is why even if you bevel and taper, you have a small gap on the bottom of each brick if it is straddling two bricks. Using one of your pictures it is easy to see between the first and second row from the plug, especially at 3 O'clock. I believe these were both beveled and tapered, but still have the angle between bricks. BTW, a plug for all to envy!

[UtahBeehiver]

Gulf,

The good old "KISS" process - "keep it simple stupid" always seems to work best!!

[david s]

Gulf,

The good old "KISS" process - "keep it simple stupid" always seems to work best!!

There is also a pretty good argument for not using a brick saw at all. Apart from simplicity, not shaping the bricks means:
Less bricks required (saving money)
Less labour (saving time and money)
Less worry (saving sleep and anguish)

Cutting the bricks in half with a brick bolster and back filling with cheap and effective home brew results in an oven as good as one made with carpentry like precision.

[JRPizza]

I'll let ya'll pie-r-square the causes . But, if ya'll don't want to get a headache, just find a way to keep the dome brick the same distance from the center of the oven and keep em' level . Hendo's IT works real well for one, and Colin's attachment to the IT works pretty good for the other lol.

Peace Gulf, stringent use of both tools would prevent droop . So would building an oven without an opening using just an IT - I just think knowing why something happens (like why you would need Colin's attachment) makes one more likely to look out for it. It's easy to see why the IT works, but if you don't understand that you probably will get droop, you would not understand why/when to use Colin's method. Droop is not something that might happen - if you blindly stack one brick on top of another (like I did) you will get droop at the arch. Forewarned is forearmed, or something like that.

[JRPizza]

Today I finished my arch integration! What a great feeling.

[UtahBeehiver]

TaDa, Past the worst.

[JRPizza]

I hope!! No build today - off to see the Huskies play Cal Bears. Go Dawgs!

[JRPizza]

Back to droop for a moment - Amac posted on Texman's build (#70) regarding droop - "The fact that the arch is in the way means that there is no natural support underneath for the bricks attaching to the arch.........when we come to that brick we try to make the horizontal joint parallel which it shouldn't be. It should be tipped up slightly." This is what I was saying from another perspective.

[Gulf]

It might not be a bad idea to start a thread on the "Dreaded Droop". I can't remember one that is dedicated to just that. Most all mentions of it, that I can remember, has been included in builds. And, most of the time it was for help to correct, the cuts required to correct, or some new technique for how to correct. At the very least, the thread may help with awareness. We all hear about, it on the fly, in our research. But, until we see it in the real world, we don't really think about it as a real issue .

[JRPizza]

I'll start one, but need to make some progress on my build first - sounds like a great rainy day task