Possible to overclock toaster oven thermostat? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: October 30, 2018, 04:33:16 pm
content: I have an old toaster oven i use as a shop tool i.e. preheating metal or drying stuff.It peaks at 450F.is it possible to adjust the thermostat on it to work at higher temperatures? I can make a external calibrated thermocouple to make a new dial for it.I dont want a external controller or anything frivilous. Its in a dusty shop. I would like to increase the temp to where practical. Like 700f would be a goal.It wont be used often at these temps, its mainly for having the ability to dry arc welding rod.If it needs external electronics i dont care for the mod.

author: SeanB
author_rank: Super Contributor
timestamp: October 30, 2018, 05:35:33 pm
content: generally those use an internal safety thermostat to limit max temperature it can reach, but in general most are simply not going to exceed the temperature because they eventually come into thermal equilibrium with the ambient by radiating the input heat away as convection and radiation. Improving the insulation inside, using more rock wool between the sides of the chamber and the outside, and some more efficient insulation ( like some of the thermal tiles that can handle being red heat on the inner but cool to the touch) will help, but you cannot really get hotter than the elements running at red heat.

author: coppercone2
author_rank: Super Contributor
timestamp: October 30, 2018, 08:56:48 pm
content: but I thought there is a bimetallic strip I need to hack some how. I can adjust the temperature from like 150F to 450F.DO you know how to modify the strip?If I can do that then I can use fire brick or rockwool or other insulation. But I need to know how to modify the thermostat set range.Even if it becomes non-linear on the dial, I can still measure it and make markings that are relevant (i.e. straw steel, blue steel, different electrode type, etc), or do fine adjustment with a thermocouple if i Need to (rare).The utility of the oven goes up drastically for shop use if you can get it to 700-800F. That way you can restore 7018 electrodes, 6011 electrodes I think, and you can blue steel. I would like for it to be able to go up to 400C or so, that way metal can be fully heated before painting to destroy all organic materials. Which will give good quality powder coat and probobly increase the quality of spray paint coatings since less crap dissolves into the paint.It would save me having to use a blow torch and be a bit safer.I have the oven setup on a rack-shelf with scrap aluminum and steel and other non-flammable things near it.If I can't modify the strip then it would mean I need to add my own control circuit to do a PID or some shit, and its not worth it with this little toaster oven to go through all that effort. Where it is right now fits the space I have available, and the ways its built is nice because you have good dust protection ETC. Anything but a simple mod is just not worth it.Still good to have a small shop oven for drying gloves and other stupid shit like that though.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 01, 2018, 01:08:17 am
content: Just move the thermostat so it's not sensing the heat as directly?

author: coppercone2
author_rank: Super Contributor
timestamp: November 01, 2018, 01:38:54 am
content: Well I had a look inside today replacing a cord for a longer one and I actually tested it. I forgot it had a TOAST mode, which goes way up. In a cold garage with the door slightly ajar because it was held up by a thermocouple wire, I managed to get something in excess of 300C. I think if the door is fully closed I could do better, and even with a bit of insulation it can do more.I see how it works, it seems it seperates something based on the knob rotation. The knob rotates quite a bit more for the 'toast' mode. If its linear, with insulation, I suspect it should trigger the thermostat at like 600F, maybe, because it seems to rotate like almost 1/2 of its full span to get to the toast mode from its maxed labeled temperature. I am going to try to make some insulation plates to put into it out of some fire brick to see if it can do better. If I lay the fire brick on the side against the control panel I could desensitize the thermostat but I was kind of worried it could melt itself. Playing with thermal resistance seems dangerous in case you get some kind of air-gap by accident that ends up being convection cooled etc.The biggest problem is actually insulation, its built like a complete bastard of bent metal and rivets. I hope I can get target temperature just by doing the bottom.