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Finally able to catch up on pictures of this weekends build. Got the inner arch bricks cut and was able to do a dry fit. Used the template method by GiannaF (thanks) and made multiple cuts from the scrap wedges from my "model" top dead center arch piece (thanks Tscarborough). Will start the bevel/taper cuts for course 2. Going to try and dial in the jig I made earlier for these compound cuts. Will let you know good or bad.
The inner arch looks great Russell!!! So what amount did you mark to cut off on your arch template? I am planning on doing the exact same thing so I am curious how much you cut off on each side.
Thanks for the email BTW. The added pictures really helped.
Thanks for the encouragement. The learning curve of the HF saw is getting figured out. The WFOers are right, take your time don't hurry, be patience. I am constantly running back to this forum for opinions from other WFOs.
Nate,
The amount of the arch taper cut off depends on a several factors, one, the radius and shape of the arch, is it semi circular or hemisphere, or other, second, how wide and thick your bricks are, mine are not the usual standard size, they are thicker and wider (3" x 5.25"), third, mortar joint size. If you have an extra $20 go down to you local HD store and look in the tools for a gadget called the Anglelizer, it is made to help make odd angle cuts on stairs and masonary, but the best part there is a software program with the jig that helps you determine arch cuts. But that said, I would be glad to run a couple scenarios with the Angleizer program when you get to that point.
PS, The spouse told me this morning that she never thought she would be replaced by an oven. I asked her if I should stop, got a resounding no since her family would blame her for no "pizza", she's Italian..........
Another way to do it on hemispherical arches where you want minimal joints (like the inside arch) is to use the wedges from keystoning the voussoirs. Note that if you want both inner and outer edges of the arch to be continuous you have to make the small end of the wedge at least 1/4" or so.
On the one below, the outside edge was going to be trimmed, so I cut the voussoirs to leave a wedge from X" at the top to zero at the bottom, then dropped them in for the tightest fit, letting the outer edge run wild.
Maiden voyage for the brick bevel/taper jig today. I reviewed JCG31's bevel/angle spreadsheet and knew I would have to make some WAGs since my brick is wider and thicker than I believe he used in his development of the table. Clearing out the cobwebs in the gray matter I used some right triangle trig. and determine my angle should be 6 degrees instead of 5 degrees from the table and that the bevel should be 1 degree instead of 0.7 for my second course.
I did a couple trial cuts and it seems to work. I proceeded to cut most of the second chain in abt a hour and the jig worked great. Did learn that brick are not from a perfect world so dimensions vary slightly. Even though I had stops I found that the variance in the brick dimension forced me to make on the fly adjustment. I should be able to hold a 6 degree angle for most of the remaining course only needing to adjust bevel.
That is the real purpose of mortar: to allow imprecise masonry units to be used. It also one of the determinates of joint size in normal masonry and why specifications allow so much variance in joint sizes, especially head joints. Fire brick ARE precise by normal brick standards FYI, and that is why <1/8" joints are specified as opposed to the normal 3/8".
I should be able to hold a 6 degree angle for most of the remaining course only needing to adjust bevel.
In my experience, that wasn't true as I went up. It depends on the number of bricks you use on each course.
The angle will be = (360 degrees/# of bricks per course)/2 [or more simply 180/# of bricks per course]
If you are using 30 bricks per course, 6 degrees is correct. As you get way up into the dome, you'll start using fewer and fewer bricks. On my last few courses I was using 12-15 bricks, and the angles were 12-15 degrees on the sides. If I had figured out that formula a bit sooner, My dome would have been a lot tighter!
That's a very good insight Dennis - like all the best ideas it becomes obvious after someone points it out.
In my experience the angles are consistent as long as the brick size is equal across the course. Once i had the trim one brick to correct an angle or taper, it is difficult to get back to the consistent angle. If i cut the whole course first, and left room for mortar in the calc, everything looked pretty and ready. Once i began setting the bricks, one or two would be out of kilter somehow and i ended up re-cutting and shaving several bricks already cut. So, i ended up cutting two or three at a time and hoping they would behave as i expected as i set them. (Gianni's advice) I can't remember how many times i thought i had two or three ready to set only to get the brick loaded with mortar and mounted in the IT and started squishing to find that it did not align properly either vertically or horizontally or both. The reason is; I cut the brick and checked alignment by hand when i should have checked alignment by placing the brick in the IT. The IT makes the face of the brick point to the center of the oven. A few degrees are hard to see the way I have to work from the outside of the oven. I set most of my bricks by touch, because i can't see the face working from the outside of the oven. Once the IT is attached and the mortar is oozing and the flies are biting and the sweat is dripping and the mortar is drying, use your fingers to feel the bottom corners in relation to the upper edge of the brick below. You can tell the vertical joint quality from above and feel the internal facing vertical joint with your fingers to detect quality. If i had it to do over again (third time) i would use les's method and use less mortar and mainly use mortar to fill the horizontal gaps and just make good vertical joints with little or no mortar.
Just my 2 cents.
Once the IT is attached and the mortar is oozing and the flies are biting and the sweat is dripping and the mortar is drying,....
...and the rain is starting and the wind is blowing, and your back is aching ,and your fingers are sore.
The ovenbuilders alternative to:
"Summertime and the living is easy .. fish are jumping and the cotton is high"
Once i began setting the bricks, one or two would be out of kilter somehow and i ended up re-cutting and shaving several bricks already cut
This is a problem on the vertical joints though if you cut too much angle. i guessed for the second row that the angle would be greater than the first, and it isn't - and I had the entire row cut I ended up turning some of them backwards to compensate. The lesson I took was - better too small an angle than too large.
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