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If you are going to be writing up the what and how, could I put in a plea for the why as well? There are lots of "I did this" out there, but not many "I did it like this because..." and it seems that it would be helpful to folk to understand some of the choices made and the reasoning behind...

The staples seem to stay put. Of the 7 or 8 HT ovens I've built so far, the oldest one I've seen lately is about 7 years old and is used regularly by a maker of fairly high-end Carbon steel and PW kitchen knives. It had an element failure early on (16 ga Kanthal A1. I now use 14 ga A1), fixed...

I have found the optimum stretch ratio to be around 3 or a little over: the installed length is around 3 times the length of the tightly-wound coil. My reasoning is pretty unscientific and there may be better advice out there. I fit the elements into routed grooves in the IFBs. the elements get...

First thing to check is whether they are All-hard or Bimetallic. The bimetal don't usually have much hard metal on and you'd need to plan things pretty carefully to keep it as the cutting edge of a knife. All-Hard are usually ok. Most places I've worked in the past, all the guys on the tools...

I've not used the Auber controller, but a quick scan through the manual suggests it should be good to go as a basic controller on the default settings, assuming you are using a type K thermocouple. http://www.auberins.com/images/Manual/SYL-2352_manual.pdf Control will probably be...

As a fairly general rule, 4-pole 3-phase motors (plated for a little under 1800 RPM) can be run at higher frequencies when used with a VFD without exceeding their design speed. For manufacturing reasons, it is much cheaper to build all motors of a particular design with identical components and...

I've been building a 27" x 7" x 6" chambered HT oven with 3 kW of elements (the maximum power realistically available from a UK domestic 230V, 13A socket). The first test run gave the following times/temperatures: 800degC (1272 degF) was reached in 22 ½ minutes , 1100 degC (2012 degF) took 54...

Way too much gas. Or alternatively, way too little air. I can't see what you are using for a burner in the Video. If it is a Naturally Aspirated burner, either it has a choke and it is closed, or your gas jet is much too big. If the choke is closed, try it open. Otherwise, in your case, a...

The SSR or relay is triggered by the controller on a time-proportioning output cycle. If your oven needs 50% power to maintain a given temperature, the controller will power the elements for half the cycle time and leave them off for the other half. This produces a saw-tooth effect on the...

The handheld pyrometers for use with type K thermocouples are pretty cheap now. I use TM902C pyrometers, at under 6 bucks delivered, from ebay. Readout is degC only and they work with type K only. All those I've tried have given readings to around 1368 degC/2495 degF, regardless of the range...

You need to take account of the starting current drawn by the motor. I'm in Europe, so I'm not familiar with the vagaries of US code and can only talk in very general terms, but I think you should be OK running through the VFD. Over here, most breakers on domestic circuits are type B. They...

A few years back, I was wondering what sort of temperatures were realistic for welding bladesmithing-type steels and nobody seemed to be able to give a firm answer. I took a type S thermocouple and pyrometer along to a hammerin where a number of good smiths made quite a lot of Damascus over a...

The Chinese HuanYang controllers are able to output up to 400 Hz for use with high-speed spindle motors. I usually program them for a maximum frequency of 120 Hz when using them with standard industrial 4-pole motors to give double the 60 Hz mains speed, which is the same as the 60 Hz mains...

If you have the kit to do it, definitely roll your own. There is no advantage that I can see to having a heavy shell to your forge. If you are going to a 12" shell though, it's going to be a completely different animal to the little Atlas. For you, I guess the answer to the thread title is no.

I'm guessing that when you refer to muffled elements, you mean that they are embedded in the walls so that they are not visible from the chamber? I had a small lab furnace a while back, made by Carbolite in the UK. Like yours, it had a large outer casing for its size, with a big air gap between...

A couple of things I'd suggest. Run the oven for a maximum temperature cycle before your final autotune run. It gets a dark Oxide layer on the thermocouple and changes its response to radiated heat from the elements. It's worth tuning at all 4 of the available temperature increments with the...

For HT and welding, you really need separate forges. I have built forges that will cope with all 3: HT, forging and welding, but only did so to see if it could be done economically. I don't really think it is economic, as I can build a better HT/forging forge and a better welding/forging forge...

The big advantage of using SSRs for HT applications is the ability to run short output cycle times. When I did my initial testing on my first HT oven, a 2-second cycle time gave noticeably tighter temperature control than a 5-second cycle at tempering temperatures. At 30-second cycle, there was...

It would certainly be cheaper to build something specifically for your needs, even if you use a commercial Venturi burner, and it will almost certainly use less gas. 90,000 BTU/hr is very close to 91,500 BTU/hr, the heat obtained from burning a gallon of Propane/hr (4.23 lb/hr). This seems to...

I think it will handle stainless, having seen what Mark is getting out of it. I'm pretty sure Mark is running at a fixed 20 PSI and doing all the temperature adjustment on the air gap; varying the fuel:air mixture, not the gas flow. It's what I did when I was doing my initial testing. With the...