iwilltry

I came up with the method myself. However, I'm sure I'm not the first to do something like this. It's a fairly obvious method if you know some basic electronics and thermodynamics.

No worries. While I think I had adequately warned of the risks, I hadn't included much discussion of how to design to eliminate the risks. Your feedback prompted me to do so, so thank you for that.

Great point about grounding the housing. I'll add it in my warning.

Despite the clear warnings I included (only bolded paragraph in the entire instructable), I expected this to draw comments. The ceramic fibre insulation around the terminals is quite thick... you don't really get a sense of it from looking at the pictures but it would be very difficult for it to short out against the housing.Realistically, this IS the kind of shortcut one takes when prototyping something that isn't certain to work. You focus on the unknowns and shortcut through the knowns, exercising extreme caution and being aware of the risks taken. Now that I know the design can melt aluminum I can add refinements (if I choose to pursue the design further). I don't need to research how to make such a connection. It's not difficult. It just takes time I didn't feel was worth investing...

Despite the clear warnings I included (only bolded paragraph in the entire instructable), I expected this to draw comments. The ceramic fibre insulation around the terminals is quite thick... you don't really get a sense of it from looking at the pictures but it would be very difficult for it to short out against the housing.Realistically, this IS the kind of shortcut one takes when prototyping something that isn't certain to work. You focus on the unknowns and shortcut through the knowns, exercising extreme caution and being aware of the risks taken. Now that I know the design can melt aluminum I can add refinements (if I choose to pursue the design further). I don't need to research how to make such a connection. It's not difficult. It just takes time I didn't feel was worth investing before proving the concept. It's not very clear in the photos but the two terminal extensions I added are actually threaded rod for the purpose of sandwiching a couple insulators between two nuts and mounting ring terminals permanently on the outside.Also I now have data from the proof of concept that can inform refinements. For example, I know that the temperature the housing reaches only about 75 degrees C, so I know the electrical insulators don't need to be ceramic. Since they will be behind the ceramic fibre insulation they will be approximately the same temperature as the housing. Teflon will suffice (working temperature up to 260 degrees C) and will be easy to machine (and I think I have some in my scrap bin). If I add them I'll take photos and update the instructable. You could argue that I shouldn't have posted anything until adding that degree of protection, but I may not pursue the design at all. So should I not post anything? Or should I post what I did and identify the areas for improvement? I expect opinions on that may vary.

I'm not sure if you think I should know better than to do it, or know better than to tell anyone I did it ;-). You might be right about the latter. But I disagree with the former. I've worked with some very educated and talented engineers over the years. Believe me, educated people take calculated risks all the time. Being aware of the risks is exactly what makes it possible to take shortcuts and get quickly to the heart of what you're actually trying to learn.