Fluctuating Temps when tempering

[ScarFoot]

Another simple way to help decrease the temp swings (depending on how your toaster controls temp) is just to put a heavy piece of metal in it to hold heat and preheat for an hour before starting your tempering run. Toasters generally aren’t well insulated and have very little mass to retain heat. Your toaster probably controls to +/- 25 degrees of set temp if your getting a 50 degree swing. Mine isn’t that bad but I also keep a heavy piece of cast iron in it to retain heat. Keep in mind heat transfer takes time so the temperature of the pieces you‘re trying to temper shouldn’t be swinging nearly as much as the air temp in the oven. A large amount of the heat being put into the oven is being lost to the outside. A PID system would certainly be more precise but you might be able to slow it down by adding mass and/or insulation.

 

[bladegrinder]

Without a PID I wouldn't use a toaster oven, at least the one I have. when I took it apart and looked at the temperature dial it just had a bi metal sensor connected to a piece of metal that was monkey connected to the outer shell of the oven. that would be absolutely worthless in my shop which goes from over 100 degrees in the summer to the 20s in the winter, that bi metal is picking up to much ambient temperature outside of the oven. I couldn't believe they used such a worthless cheap temperature sensor for this thing.

 

[Natlek]

My error. Yes, that one has a fan. I was typing too fast and didn't say what I meant. I changed the post comments. Getting old ... I can't even blame it on translating from Macedonian.
My point was few makers have one like that. It was the cheapest I saw in a quick search for convection tempering and similar ovens. Most were $15,000 and up.

Среќна Нова Година

$ 4000 - $15000 for oven ? We can build it for under $300 even in USA Check *Autoclaved aerated concrete* https://en.wikipedia.org/wiki/Autoclaved_aerated_concrete stunning material and very very cheap with excellent thermal properties and ideal for tempering oven .And t is produced in right dimensions for oven for easy build ...... Electric stove heaters are rated to 750 Celsius .. so we can make tempering oven for higher tempering temperature , 500-550 Celsius .

 

[Stacy E. Apelt - Bladesmith]

Instead of derailing this thread, I suggest you start a new one and do a build tutorial on making that oven. You certainly have a gift for building things on the cheap and finding parts and supplies we can't seem to get.

 

[Ken H>]

The PID:
Most cheap PID controllers are pretty much the same. You want 120VAC input and the ability to take a type K thermocouple.
They often come as a package deal with the PID, SSR, heat sink, Thermocouple, and wires.
Amazon search - PID Temperature Controller Set, PID Temperature Controllers Thermostat Regulator, SSR 40DA Solid State Relay AC 100 to 240V, White Heat Sink and K Type Sensor Thermocouple

Stacy, I didn't check close enough before ordering that PID, but it is °C only. If a person doesn't mind working in °C it's just fine and a darn good price. Boy do I wish we'd just go metric only - life is simpler with metric. I was thinking about putting it on a Green Egg to control temps, but for grill I do like °F. The description does say " It also supports Centigrade and Fahrenheit reading", but from the model number I got it's Celius only, and at least one review (which I didn't check before ordering) says Celius only.

 

[Judcargile]

These guys are spot on with the temp controller.
They work so well, that you can do the high end of HT on stainless in a ribbon burner gas forge.
For tempering, I would look for a controller that has a range of 0-500F, matching the controller to the process gives you better resolution / better accuracy.
I am a single father and have the luxury of using whatever appliance to whaterever means needed.
I bought a small oven for doing kydex. That crap is not going near my kitchen. I supervised with a pyrometer and it seemed like a butterfly on a string. I took it back for an electric griddle and was getting the same crappy feedback.
I tried to dig a bit deeper and noticed that these cheaper units seem to use a thermostat that goes to full range and THEN settles back to set point; So, you might be getting the same trick played on you.
What you really need to do is send her to get her nails done and use the oven in the kitchen: Maybe that is why I live my daughter?

 

[Stacy E. Apelt - Bladesmith]

After using the kitchen oven for tempering, always volunteer to fix dinner or bake cookies.

As the saying goes, "If Momma ain't happy ain't nobody happy."

 

[Signalprick]

When we upgraded to a gas stove in the kitchen we moved our electric oven to the basement utility room where I have my shop. It's been great for tempering. I just upgraded my kiln to a 240V unit and we only have the single 240V receptacle so I purchased on pre-order the new Qstoves ElectriQ. It looks like it was made for tempering blades. Lol. Worst case I'll be able to make a decent neopolitan.