Inner arch template - what have I done wrong?

[Canada 150]

I've started to lay a few chains of brick and things are progressing. I've been putting off the inner arch but built the template last yesterday to try an integrated arch

as you can see in the attached photo, where the face of the inner arch template meets the dome profile template (36" ID, 18" radius), I seem to have a gap vs pics I other threads where the dome profile intersects perfectly with the arch template.

do I bring the inner arch into the dome more? Guidance from those that have done integrated arches?

Cheers

[shanxk8]

I just finished my inner arch today, so will share some pictures of what i've done. (Also, it seems your photo didn't attach properly)
My the outer edge (front) of my inner arch is 18" from my mid point of my IT (same distance as the inner edge of my dome, i'm building a 36" oven)
First picture is my cut inner arch bricks. The notch on front top is cutout for heat break and for outer arch bricks to sit on. They are sitting on an angle, because i cut an angle off of the back so that they follow the curve of the rest of the oven dome (not sure this is standard practice, i don't think i took a side view of those bricks, darn).

I figured out where the inner edge of my arch bricks needed to reach using my IT tool. The 2nd, 3rd, & 4th pictures are of the completed arch. I think i'll go outside & get a couple better to help show what i've done. (we shall see if it works as i progress with the 3rd courses of dome bricks and beyond) I found the arch laying to be a fair bit more finicky & stressful than the dome has been so far.

I have removed my arch template and it didn't fall down, so must have done something correct!!

[shanxk8]

Here are a couple more pictures that might give a better idea what i did with my arch. I rested my IT tool on the arch so you can see where arch bricks sit relative to it.

[UtahBeehiver]

It appears that you only have a portion of the tapered inner arch. Here is a pic of one done with a similar type partial arch with straight walls on the base. What you see from the picture is your current arch has the inner diameter of the dome like shown in the attached picture below the lower blue line. What is missing is the slope of the brick course which is the section between the upper red (outside diameter of dome) and lower blue lines (inside diameter of dome). Also attached is a cross section picture of a single brick and what the profile should look like.

[JRPizza]

I can't see Canada's pictures. Is there something wrong on my end or are they missing?

[shanxk8]

JR, I also cannot see them. Looking at Russell's picture I wonder if I have done mine a wrong, might be doing some cutting with the grinder to make them that shape

[JRPizza]

I also missed that Russell was addressing Shanxk8's build, not Canada's. Yes, the top of the arch in posts 3 are flat/parallel all the way across, where most of the arches I have seen (and what I copied) have a flat forward portion and a rear portion that is angled to match the bricks in the dome on either side. This keeps your mortar joints on the outside more uniform and probably is more structurally sound. I put a brick in my IT and used it to trace the angle at that height onto my arch brick (upper left diagonal line), which you can see in the first picture. I used the IT to trace the lower left diagonal line, which represents the interior of my dome (the upper right line was drawn in error). If you cut the brick along those two left side lines it will look like the brick on the left in Russell's picture. My second photo shows how the dome bricks sit nicely on the slope of the arch bricks.

[Canada 150]

Hmm. Ok I'll try and repost pictures. I posted from my phone so likely something going wrong on my end.

[Canada 150]

Ok, let's try this again! The first picture if a reference to show the 36" ID reference line within entryway - The inside of the bricks at the entryway is where the 18" opening intersects the 36" floor



When my inner arch template is lined up against the 18" entry line, I get a gap where the dome template (18" radius) and the inner arch template intersect (see picture 2). As I look at JR's dome calculator again, I see that it projects dome height of 18.5" and radius of 18" - I wonder if this is my problem as I made the dome template a constant 18" radius - maybe I taper from 18.5" at top to 18" at floor?

Option A (picture 3): The next picture show the brick orientation and IT with the inner arch template aligned to the 18" entryway opening - it looks too far out to me (ignore the pencil lines for now)


Option B (Pic 4 and 5) if I move the inner arch in towards the center of the dome, to the point where my IT intersects, it looks better, but I'm off my 18" door entry width line (you can see the template moved in in the first picture). Pencil lines on brick show where IT positions a brick at this point:

[JRPizza]

Canada, the dome calculator is DJ's, not mine. I'm not sure if I could have created that spread sheet, and if I did it would have taken me a loooong time. Are you using both a dome template and an IT? I am not sure the template will buy you much if you have a proper IT. In your 4th picture, it looks like you have your arch form moved back from your front face of the bottom arch bricks, but have the top dead center brick aligned with the edge of the template. You want all of the arch bricks in the same vertical plane, so I believe you need to move the template forward like I show in my picture to align with the front of the arch on the bottom. Then when you place your TDC brick like in your pic #5 &6 and cut along the lines it will look like the upper arch bricks that Russell and I show. The TDC brick should be your longest brick - as the dome "recedes" back due to curvature, the arch bricks need to go deeper to remain attached to the dome. I can't tell if you h

[UtahBeehiver]

How thick is you floor template. Depending on the thickness, this will affect the dome height and all points gradually to floor level. Leave the arch template so it aligns with the 18" radius at the floor. The inner diagonal line can be adjusted to it intersect the top of the arch for the taper arch ( you are only looking at about 10 or so arch bricks. This area is not seen after the build is done or you can leave a lip as well. I would have the front end of the brick pass the front of the arch template rather than even with the edge. this gives you some material to work with to tie in your vent chamber area. Another option, if you IT is adjustable, extend the IT so it reaches the arch template and adjust in as you go down towards the floor. Lots of ways to skin this cat.

[Canada 150]

Ok many thanks JR and Russel for your guidance. I will keep the template flush with my enterance and just work to angle the brick a bit more so it intersects the dome.

After trying (and failing) to cut the arch bricks with a taper today I think I'll invest in some tapered bricks and try to start the arch next week.

The he ccer I have inside is only <1/4" cardboard. I had made the dome template based on someone's build but I think I can get most of the lines off the IT tool.

just to be clear the top angle line is the line as if I were place a brick on top of the brick that forms TDC of the inner arch - correct (ie the next chain)?

Cheers H

[JRPizza]

Yes, on my arch the top angle was what I needed so the brick that went on top, when held in position with the IT (proper distance from center and proper angle) would sit tight on the inside and have room for mortar on the exterior. You can kind of see this in my second photo of post #7. If I had made the angle exactly along the line I drew in pic #1 the brick would have had a uniform mortar layer between it and the arch brick, so I cut it a little shallower. Does this make sense? I also built my arch as I built my dome. Some folks can complete their arch first, but I found it easier to build as I went and see what angles I needed to cut to get the bricks to match.

[UtahBeehiver]

Are you using a wet saw and what size is it to cut your arch tapers. Here is a pic of how I did mine using a 10" wet saw. I had to cut from both sides and use a grinder to take out the middle. You do have to be careful when building a arch as you go. You get mortar creep on the joints then all of a sudden when your at TDC the last brick is either too small or too big and it is quite obvious. I also have a program that can calculate the top and bottom widths of the brick based on brick size and diameter and mortar joint size of arch you are interested let me know. I can't send the program but I can run it for you and send a screen shot of the results.

[JRPizza]

I did similar to Russell (I pretty much copied his build as much as possible) in that I had a 10" saw and cut from both sides. I started my bricks upside down from what he shows, and with some careful indexing against a hard stop did not even have to use a grinder. I 3D printed a jig that had both the proper angle and build in hard stops, which you can see in the attached picture. You won't really see much of the inner arch when you are done, but tapered outer arches look better to me and if you taper the inner arch you will be a pro by the time you get to the visible parts. The mortar creep is a real thing, but you can mark locations on your template and fairly much avoid it (you can see this on post #28 of my build thread). Some of my joints are a little bigger than the others but you have to be looking for it to be noticeable. Are you building a full hemispherical arch or going with the flatter type? I have a copy of the program that Russell used, but I ended up making a spread sheet (I had too much spare time plus wanted to understand the results) and I can give you a copy if you want (as long as you are making a semi-circular arch).