Oven - responses to above comments
David Utijian - Re where to put the hot cover: The top two photographs show a freestanding rectangular platform sitting on the bench next to the oven. This is on 1-inch legs, and was made to put the hot lid on after removing it from the oven. There is enough room on it alongside the lid for tongs and a couple of small hot doodads.
gzig5 - Re cost: I did not keep a ledger, but I would guess something under 225 would be right. The controller, thermocouple, and element each ran about 30 bucks, the SSR about 10 bucks. The bricks were a bit under $4 each (less than half the McMCarr price), and the refractory mortar another 20. The angle and expanded sheet were from the local hardware store.
.RC. - Yeah, made just for my own personal shop use, not as a for-sale item.
jimboggs - Re time: Didn't keep track of hours, but as is often the case with these things, the very great majority of the time spent went into planning, figuring, & thinking about things. Having gotten the first one done, the actual construction time for a second one, which I'm not planning to do, would be two full days once all the materials are in hand. You'ld want to leave the mortar to set at least a full day, undisturbed, after doing the brickwork.
Re size: The interior of the oven measures 8.5 in long, 4 in wide, and the usable z-distance above the rack is 1.75 in.
Re availability of plans & parts: Leaving aside the fact that I have no set of plans and no official parts list, I am really reluctant to say too much, since I don't know that my construction decisions are the best ones. I designed this oven pretty much as I went along, and my purchases of parts were mostly governed by what I stumbled across using the internet, not by a careful analysis of costs or features, although my friend Larry did do a pretty sophisticated study of element wire gauge, coil diameter, and gyre pitch. I'm not trying to hide any secrets by evading the plans issue, and would be glad to answer any specific construction questions that pertain to this oven.
scatter cat - If I understand your suggestion correctly, your concern is electrical hazard from touching the element terminals. Where the two ends of the element wire lead through the oven wall to the outside, they travel in a small ceramic sleeve. Right at the outside wall of the oven they connect to the hookup wire, which is wire with high-amperage insulation that can be bought from pottery kiln manufacturers. The connection is mechanical, by means of steel cuff-shaped connectors I made up in which the wires are clamped together by means of setscrews. If you look at the bottommost photograph of the three I posted, you can just see the upper one of the two element connections. The round white thing at the oven wall is the outboard end of the ceramic lead-through. The shiny grey material which appears continuous with it is a goobered-on coating of JBWeld, which bonds well to the ceramic tube and to the initial portion of the insulated hookup wire, and which is non-conductive. You can touch it without getting shocked.