36" build in Tallahassee - AKA Bruce's Folly

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I wanted to share the technique for laying out semi-circle (Roman) arches. Here's an example with arbitrary numbers

First, you need to know your span...lets say 20 inches. Draw a center line at 10" that crosses (at a 90* angle) span line ( spring line) on both top and bottom, at least 20". Now lets say your rise is 10"...mark that on your center line. You now have three points of a triangle.

Next, measure your distance starting from the center point of your rise, to one sidepoint of your span...right or left. Now, draw a line between these two points, and mark the center.

Using the line you just made, set a square on the line on the center point. The square is now crossing your center line below the high point of your rise. Draw a line along the square until you cross the center line.

This point is where you set the point of your trammel or whatever you are using to trace the arch. Now you have a perfect semi-circular shape for your form ( called centering in masonry).

If you know this already, forget everything I just typed.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday Bruce

What's your thoughts on what's a usable size in height and width for you in the chair? In saw the pics of you trying out the peel would I be right in saying the width would be better to be bigger?

Regards dave

Thanks Dave,
I went back and looked at the photos, the only problem I remember in Colorado was the height which was awkward (pics 1 & 2). You may be thinking of pic 3 from a few days ago. It is actually a heavy mop that I was using to swab the back of the oven. I don't think a 9"-12" entry will be cause problems working from the chair.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I wanted to share the technique for laying out semi-circle (Roman) arches. Here's an example with arbitrary numbers

First, you need to know your span...lets say 20 inches. Draw a center line at 10" that crosses your span line on both top and bottom, at least 20". Now lets say your rise is 10"...mark that on your center line. You now have three points of a triangle.

Next, measure your distance starting from the center point of your rise, to one sidepoint of your span...right or left. Now, draw a line between these two points, and mark the center.

Using the line you just made, set a square on the line on the center point. The square is now crossing your center line below the high point of your rise. Draw a line along the square until you cross the center line.

This point is where you set the point of your trammel or whatever you are using to trace the arch. Now you have a perfect semi-circular shape for your form ( called centering in masonry).

If you know this already, forget everything I just typed.

Stonecutter, I need all the help I can get working out the arch. I think I understand your instructions and will try the technique shortly. Assuming I am able to successfully trace out the arch, what is the next step? If you assume total ignorance on my part, you are still likely overestimating my knowledge. Thank, Bruce

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Something that is nice to work with and makes nice forms, is 2" rigid foam insulation board.

You can trace your shape on it, then cut it with a jig saw ( fine tooth blade) dry wall saw, or razor knife. The later won't cut all the way through, so you snap it like dry wall, then clean it up.

Make three of these and you can screw them together for a fast easy form. I had foam EIFS board laying around, and that is what I used for my entry centering.

I won't be online until later but I can diagram this technique later if you run into trouble.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I wanted to share the technique for laying out semi-circle (Roman) arches. Here's an example with arbitrary numbers

First, you need to know your span...lets say 20 inches. Draw a center line at 10" that crosses your span line on both top and bottom, at least 20". Now lets say your rise is 10"...mark that on your center line. You now have three points of a triangle.

Next, measure your distance starting from the center point of your rise, to one sidepoint of your span...right or left. Now, draw a line between these two points, and mark the center.

Using the line you just made, set a square on the line on the center point. The square is now crossing your center line below the high point of your rise. Draw a line along the square until you cross the center line.

This point is where you set the point of your trammel or whatever you are using to trace the arch. Now you have a perfect semi-circular shape for your form ( called centering in masonry).

If you know this already, forget everything I just typed.

I tried to draw this out, but the arc would curve in about 3" before meeting the outer edge of the side.

The entry's dimensions are: 18 1/2" across hearth floor with 2" of brick to the outside. The height from the floor to the peak of the arch is 12 1/2" with 4" of brick face to the top. The distance from the hearth floor to the top of the stand is 6". The distance left between the front of the oven and the front edge of the stand is 13".

Thanks again. Bruce

[cobblerdave]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday
Draw you dimensions on full size on a large piece of paper . Draw a centre line . Rough out one side only it might pay to use something flexible like a piece of hose etc to get the curve. Once you have what you like fold in 1/2 and use a pin to trace through to the outer 1/2 side . Draw that in you should now have something symmetrical . If its not what you want easy to do it again
Regards dave

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I tried to draw this out, but the arc would curve in about 3" before meeting the outer edge of the side.

The entry's dimensions are: 18 1/2" across hearth floor with 2" of brick to the outside. The height from the floor to the peak of the arch is 12 1/2" with 4" of brick face to the top. The distance from the hearth floor to the top of the stand is 6". The distance left between the front of the oven and the front edge of the stand is 13".

Thanks again. Bruce

O.K. Bruce, I worked something up on paper, to help you see how to strike the lines, and show you how a semi circle arch will work with your oven opening.

Here is the picture..it's the best I can do with limited CPU skill. Just click it to enlarge.....I downsized it to load faster.



First, I used your dimensions above, 18 1/2" Span, 12 1/2" rise. But I didn't know the height of the springing line for your oven arch. I went with 8" after trying it with 6" & 9"....because the radius looked the most like the one in your picture.
*Your existing oven arch is marked in Blue.

I put the span of the vent arch at 24 1/5", which gives you a 3/4" reveal on the apex and then opens up quite a bit on the sides. This is what will happen on any semi-circular arch (if you choose to do this). The numbers I used give you a good reveal, and kept the widening out on the span to a minimum.

I left the layout lines for you ( and anybody else that might want to learn this) to see what I mentioned earlier.

Note the center-line, were I marked the desired rise. In this case 3/4" above your oven arch.

Line "A" starts at the rise point and runs to one side point of the span. This worked out to 18".

Line "B" has a mark at the center... 9". Then a square is placed on "B" holding on the center mark. Trace a line through the center line of the span.

This is were you place your hold point on a trammel or string line.

Starting on either side of the span, trace your arch...it should travel perfectly through the point you marked your rise, and connect to the opposite span point.

This gives you a method for creating perfect semi-circle forms for any size arch.

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I realize a semi shows some mortar on the outside of the brick of the oven opening, but an arch like this has a couple advantages.

1) Easy to build

2) Greater strength, and the shape eliminates the need to buttress the side walls.


You will need to build up the support so your arch springs from the same point as the oven arch. You mentioned 6"...so that is what you must do, otherwise the span must be much,much greater to give you a reveal above your oven opening.

I suggest using CMU units mortared directly under your springer brick (first ones in an arch) then you build a firebrick floor for the vent area.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Stonecutter, thanks again. I followed you up to here.

I suggest using CMU units mortared directly under your springer brick (first ones in an arch) then you build a firebrick floor for the vent area.

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

You need to start the outer arch on the same plane as your oven arch. The slab in front of your arch is 6" ( I think you said) below the top of the floor brick.

You can use CMU ( Concrete Masonry Units)* to build up to the correct height without much trouble or added formwork. These will not be seen, as the springer brick will be over it.

Then, the floor inside the vent area, which would be inside of the vent intrados, can be build as usual...out of firebrick.

* You can get CMU brick or 1.25"x8"x16" to make handling easier and so you don't have to cut.

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Bruce, this may be a bit presumptuous, speaking for others but.....

I think it's safe to say that we are rooting for you on this build..not because we feel sorry for your disability, but because of the determination and grit it is taking to get this done in spite of it.

I don't usually get this in depth with layout explanations, but if you need more I'll be happy to continue.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Bruce, this may be a bit presumptuous, speaking for others but.....

I think it's safe to say that we are rooting for you on this build..not because we feel sorry for your disability, but because of the determination and grit it is taking to get this done in spite of it.

I don't usually get this in depth with layout explanations, but if you need more I'll be happy to continue.

Stonecutter, no I don't think you are being presumptuous. There is no question that I took this build on in part as a personal challenge and recognized I would need advice and support throughout, though largely due to my knowledge and skill level rather than physical limitations. If I receive additional interest, help, and attention due to my physical limitations, I am completely ok with that. I appreciate your help and in the case of the arch, can really use it. I will work out the forms (I picked up some foam board), let me know if there is any special trick to assembling . I am having trouble visualizing the brick tapers and layout. I feel like I am near the finishline, and the entry is the last real stumbling block.

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I used 3" screws to assemble the form.

[stonecutter]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Also, you shouldn't worry about tapering any brick in the arch except maybe the key. Once your form is made you can set it down and do a layout to see how everything works out ..

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Also, you shouldn't worry about tapering any brick in the arch except maybe the key. Once your form is made you can set it down and do a layout to see how everything works out ..

Thanks again. I will be getting to work on it in a bit. By the way, your diagram cleared things up. I had not quite grasped how to locate point C and was placing it too high. I rotated the image and will attach. I picked up some foam board yesterday, it should be much easier to cut to shape than plywood.