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Hello. I have built an electric tube furnace using nichrome wire, an AC contactor, and an Auber Instruments SYL-2342P PID controller. I have the basics of programming it figured out but the furnace can never get above 1525 F before the controller switches to "stop" mode. Here is my program: C01->50 t01-> 90 C02-> 1825 t02-> 15 C03-> 1825 t03-> -121 The furnace heats up no faster than about 1-2 F per 5 seconds. What am I doing wrong? Is there a setting that is triggering the shut-off prematurely? Any help would be appreciated.

I gave up on LPG or propane about 10 years ago in favor of diesel. Diesel is cheaper and easier for me to store and doesn't suffer from 'freezing' issues . When I was a boy, I had to light diesel furnaces every morning. In exploring diesel as an alternative I hunted high and low for the burner design I had seen in use in industry. I finally tracked it down to a New Zealand patent from 1936. I scaled my rough drawings from the patent , producing this 'prototype' ( never stopped using it) and several larger burners for other furnaces. These burners require a little bit of skill to set up and run , so they aren't for beginners but , if you are running fires all day, they are worth the effort to learn. If anyone wants a set of drawings PM me and I'll sort something out for you. https://goo.gl/photos/zCrRp4Tav6ep8ZZe6

So as of late while gallivanting around the site, I stumbled upon the concept of "Aristotle's Furnace", so I got to thinking; I'm an amateur with some free time coming up due to fall break, I have an excess of clay that I processed, and I have a passion to make some good steel. So the thought occurred to me that rebar could perhaps be a cheap alternative that is readily available and can be cut into bits and melted down in the furnace. I am even thinking of making my own charcoal for this project. Does anyone have any other suggestions for cheap, readily available iron or steel sources? Also your thoughts on the process of purifying rebar into good steel would be greatly appreciated. I've read that the steel content varies greatly in rebar, so perhaps after a go or two through the furnace I could sort out the soft steel from the brittle steel much like Japanese smiths do. If there are any experienced folks that would be willing to weigh in on multi use clay bloomery/furnace designs that may prove to be more fruitful, then I'd highly appreciate it. Side note: it is preferable to keep the furnace reasonably sized and transportable.

Hey everyone! This is my first post, and I am making it as I ramp up towards my first smelt. I have been going over the posts here and have been able to get a lot of the details of my first smelt down, like ore type, flow rates, charcoal creation, furnace design, etc... What I haven't seen though is any talk about the internal pressure of the furnace and what effect it has on a bloom. I was thinking of modifying one of the Rockbridge furnaces to increase the internal pressure as a way of increasing the temperature. Has anyone tried doing this? If so, was it helpful? Hurtful? Aside from a different way to regulate temperature, I'm speculating that the rate of reactions inside the furnace would increase at a higher pressure, so I wanted to try it to get a better yield. Anyways, thanks for all the great info so far! -Bryan