Hi, DT,

We use Marlin firmware with slight mods. We will publish our source code, so you can always grab it and recompile. The reason I mention this is that the min and max temperature parameters are compiled into the firmware.

Currently Min is set at 170, for no better reason than that it was that way in the stock version of Marlin. There's nothing to prevent you from making it lower, if you end up wanting to work with much lower temp. materials. In fact, we're working with a company that is developing a material that will require us to do just that. So we'll see.

We've run up max to 250C, just to see what would happen, with no ill effects. You want to make sure that you do that with either an empty filament path or with filament that won't cook at that temp - something like the Taulman Nylon 910 (print temp 235C). If you try that with most PLA and ABS filaments, they'll cook to a nice black sludge for you, and you'll have fun removing it from the nozzle. Been there, done that, wasted many hours cleaning it. :-)

Fundamentally, since the entire filament path is all metal (Aluminum, Titanium and Brass), the first limit on high temp is likely to come from the Teflon tubing used to insulate the thermistor wires. Teflon melts at 327C. Somewhere about the same temp, the cooling fan on the lower heatsink, will probably be overwhelmed. It's probably made out of ABS and might start melting. So I wouldn't take it over 300C.

Ben