So, you know about better ones? How much do those cost?
For this application, I have no idea what’s out there in terms of a consumer market. But if it's a decent size chamber, with multiple shelves and no independent thermal control, I'm not sure I'd purchase it. I guess it all depends on what you need for a tolerance spec., and how well the chamber controller is spec'd..
My experience was in a lab environment where precise heat and pressure control were required. Specifically, out gassing of military parts were being evaluated about a set point, and shelf temp had to be set with a tolerance about the set point spec. We kept having problems because technicians didn't understand the concept of thermal time constants.
Sounds to me like Fade is talking about a converted environmental chambers or something where the thermal path/control isn't very good. I can’t imagine having to preheat a thermal sink every time you want to use the thing and then how do you control it about a set point without an active bidirectional source? Imagine, you heated the stone, the thing is way too hot, you have no way to bring it back quickly because the thermal time constant is too damn long. I bet he’s got a mental algorithm and he heats the stone close enough that he doesn't fuss with it. He’s a pretty clever guy.
For what I do, a thermal oven is way over kill, I’m not a big volume guy;
However a vacuum oven project would have merits all on its own. Doer, you like building stuff, you program the arduino; sounds like a good excuse to buy a tig welder and plasma cutter!
This will be good experience for you, because if you start welding you’ll eventually require a thermal chamber for heat treating and the machine shop you’ll eventually acquire.
Good luck.
