Simmental Farm 36" Pompeii and 48" Rumford Style Fireplace

[Gulf]

With the arch brick dry stacked we started scribing the arch with the ID and OD tools. We discovered that the arch was placed too far forward.

On the drawing, I had plotted the first riser and the top dead center arch bricks. That works well for a hemispherical arch, but this is a segmental arch. On a segmental arch the top risers and springers (skew back) protrude furthest into the dome away from the face of the arch. I went back to the template later to see how that could have been predicted. The third pic shows that adding the height of the risers to the inside face of the first riser places it outside of the ID of the dome.

We moved the face of the arch in to 19" from the center of the dome. That move gives Don a slightly deep entry. He's okay with that since he wants to use that area for grilling steaks.

[Gulf]

The oven floor brick were scribed and cut to fit inside the dome walls allowing for a cardboard space as an expansion joint.. We taped the cardboard spacer around the perimeter and laid the first course of dome brick. Next up was setting the arch form. The face of the form was set 21 3/4" from the center of the dome. That placement was soon to be changed.

[Gulf]

In total, there were four all thread attachments built for this oven. The two IT's and a couple of attachments used to scribe the inner arch.

The scribing attachments were also made from all thread. 5/16th in this case, because it fit one of my old coping saws without alterations. Both scribing attachments are fitted to the pivot point as was the ITs.

[Gulf]

Extra holes were drilled in the bracket for wood screws to secure the bracket to the wood blocks. The IT is built heavy duty since it will be used for multiple builds and also for another reason that will be apparent later in the build.

[Gulf]

The IT head is made from an off the shelf corner bracket, an all thread connector, a bolt, and a nut to lock the head in place. The 6"X6" bracket was cut down to fit the dimensions of the 1/2 bricks used to build the majority of the dome. I used some slightly less than 3/4" blocks that were cut from an from old bed slats. I'm not sure of the species of wood. I cut thin plywood spacers from 1/4" and 3/16" stock to align the the all thread connection with a factory drilled hole that was in the bracket. This was to align 1/2 the thickness of the brick.

This IT was designed to be cut down later, but we decided not since it will be used for another identical build. So, Don made a second IT that was narrower for the 1/3rd and 1/4 bricks on the upper courses. The head of the bolt used was cut down to allow it to be easily countersunk in the wooden block. I used a hand drill for this on the full sized IT but, Don has a drill press that makes it a little easier for building the narrower IT.

[Gulf]

That adjustment point (only to set the final adjustment) is an all thread connector at the base of the IT head. A nut is threaded in line against the connector to lock the IT head in place.

An addition to this post is coming. My bed is calling me now. It's been a long cold day down here in Mississippi .

[Gulf]

My first IT had at turnbuckle mated to the all thread for adjustments. The new IT does not. My first IT was not designed to be center of the brick. That may have been the reason that I did not have adjust the IT during the build. I'm not sure? This one is designed to have the direct center of the dome inline with 1/2 the thickness of the brick. No adjustments were needed during this build either. Only a minimal adjustment point was designed into the new IT.

[Gulf]

Thanks Mike,
Later in the build, or perhaps at the end, I intend to include all the measurements for this 36" oven and also how to draw the full scale template to fit any hemispherical oven..

Kvanbael,
Great job on your IT!. That will do nicely. I particularly like how your design allows for quick removal and replacement of the IT for touchups, clean up, etc.

I will edit the post to read "most" .

[Kvanbael]

One of the problems with designing an IT is the pivot point. All that I have seen used so far have an offset

Wel... Mine had no offset. Granted, it wasn’t perfect, but at least my dome’s center is flush with the Floor. I only had to drill a tiny hole in the center of my floor to hold a nail.

[SableSprings]

Joe, this is an awesome build thread. Incorporating all the innovations forum members have made these past years makes this into the perfect diy guide. I think that "we" should make this IT design the defacto for building a WFO. Cut the thread stock above the pivot attachment & use a threaded sleeve and this could be sent to another builder in a pretty small box (they'd only need to buy the threaded stock for the other end of the sleeve to reach the projected outer wall). I also love showing the advantages of the cardboard template in doing a build layout.

Great Job! Looking forward to the upcoming posts.

[Gulf]

Married with a wooden brick this creates a no offset pivot point.

Don drilled a 5/8" hole and a slight 3/4" counter sink hole underneath in my old wooden brick at the exact center of the dome floor. We had to rout a counter sink in the top to allow free swing of the IT for the first course and scribing the floor brick.

The exact center point is easy to find for the rough placement of the wooden brick before cutting to find where the wooden brick needs to lie with the full scale template. For the final placement it is easy to mark the direct center on the wooden brick with the center point hole provided in the template. Just line the template up with the center line marks front and back on the concrete hearth.

[Gulf]

One of the problems with designing an IT is the pivot point. Most that I have seen used so far have (including my first IT and wooden brick) had an offset. That offset can lead to having to make adjustments . For many years I have found myself looking for something that could be used for an off the shelf, no offset pivot for an IT. So far, I have not found it.

Still determined, I decided to build one

Pic #1 is a 5/8th diameter X 2" clevis pin. I cut a notch perpendicular to the predrilled hole for the pin. I heated and flattened a 7/16" all thread. (The thick all thread has enough diameter so heating and flattening to widen the attachment point may not be necessary. However, it will still need to be ground or filed down to fit the notch in the clevis) I then drilled a 3/16th" hole to match the clevis pin hole and a ss bolt.

The bushing in the first pic was not used.

[Gulf]

This is my 11 year old HF saw, ready for another project. It has paid for itself many times over for me. I no longer had all the parts for my improvised commode float to rig up in the bucket. Don saw the need and put a float regulator that he uses in his stock water tanks. This is an economical improvement for folks wanting a clean water supply to their wet saws

[Gulf]

The insulation template was also used for cutting the 3 layers of 1.5" CalSil. Some experienced folks with a good eye will notice that this is scored insulation. Scored insulation has v-grooves that allow it to fit around large diameter piping. I have made several posts on threads warning about not using it for the floor insulation. In this case it was obtained at a bargain price.

I said a "bargain". But, sometimes bargains have hidden charges! We devised a way of cutting wedges on a table saw to fit the holes on a table saw. The saw was fitted with a vacuum collection system. We both wore NP95 masks and had a fan blowing any excess dust away from us. So, we thought that we were ok. ...................We both lost a couple of days of work on the oven with sinus problems. Don had to get a steroid shot. Both of us were thinking that we had contracted Covid. As it turned out, we both had "CalSillyAsstosis"

It's a "silly" disease because we both knew better. Obtain solid board insulation or just live with the air spaces in the crap. It ain't worth trying to fill the gaps IMO.

Oh well. We are both seniors. But, you younger folks that want to live forever need to take warning!

[Gulf]

We placed 2" mosaic tile sheets upside down and used another template to mark the footprint for the board insulation. It makes it a lot easier if the center line is marked front and back on the hearth slab for future reference. Those marks will be needed for several steps during a build.