Building a tempering oven

[JTknives]

I have relized I need a dedicated tempering oven. Not looking to take on a huge project like my heat treat oven build. This leads me to ask for your advice on what you think.

My thought is to insulate a large air tank and use a heat source with a blower to pump the air into the chamber. This would be wired up to a SSR and a pid with a TC. I have a few tanks that I think would work well and would be simple to modify. My first thought was to use say a 2" Diamater black pipe ran along the roof of the tank. The pipe would stick out the rear of the tank. Inside the tank this pipe would have holes along its length pointing to the left or right. I then would use somthing like a heat gun stuck into the pipe and wired up to the SSR. I'm thinking I would re-wire the heat gun so I can control the element and blower separate. Maybe keep the blower on and cycle the element on and off. I would insulate the outside of the tank and put this inside another tank. Of corse I would need a vent of sorts to allow the blown air back out without to much back pressure. The vent could just be a series of holes through the inside tank and let the air vent through the insulation and out a few holes in the side of the outer tank. The floor of the tank could be horizontal metal bars going from one side to the other like a grill grate. This would allow the air to circulate around the blade and create an even heating. By not having any exposed elaments I would eliminate IR problems.

Here are the two tanks I'm thinking about using. The blue one is 11" by like 22" the red one is bigger which would allow for plunty of insulation. The picture of the air compressors is just to show the tank. I have another compressor just like it that has a rusted pin hole in the tank and has been retired for parts. I would use that tank.

Let me know what you think. I know it's kinda hair brain and off the cuff but I need something better then a toaster oven and I hate waiting for my big heat treating oven to come down in temp.

 

[Busto]

There is a used appliance store not far from me and I went by to see about a chest freezer and whadaya know as I walk in a $50.00 used stove...Paid the guy $10 to deliver got a 2 week warranty and that was 3 years ago. Ya might call around see what's available easier than fabrication (and I like to fabricate)

 

[Drew Riley]

I'm with busto. No need to re-invent the wheel. Just get a used gas or electric stove, maybe insulate it a little more, then wire in your own PID and a TC or two, bada bing!

Maybe add some thermal mass if the temps are jumping around.

 

[Busto]

The one I purchased was from an apartment complex that was installing all new appliances and the Used store purchased all of them. I know it was all about Perfect Timing so I got lucky. It not a Honking monster stove so it's reasonable to do tempering....The added PID is also a good idea!!

 

[Stacy E. Apelt - Bladesmith]

A used convection oven is the best choice. It will also heat up a pizza for late night shop snacking. They can be found surprisingly cheap. The two or three shelf cookie convection ovens from sub shops and restaurants can be found for less than $100. The big commercial kitchen rolling cabinet units that sell new for $3-5000 are often found at used kitchen equipment sales for $200-500.

A second choice is a new or used in-wall oven. They are well insulated and can easily be converted to PID control. These can regularly be found at places like Habitat for Humanity and other charity stores for almost nothing.

 

[JTknives]

I love my wife's convection oven and that's is what I use right now but we are moving to the new place and I don't think it has one. I did not want to go with a standard oven because I love the air circulating feature. But if I could aquire one for a good price the I would not need to make one.

 

[Drew Riley]

A used convection oven is the best choice. It will also heat up a pizza for late night shop snacking.

Ah yes, Parks 50 and pepperoni... a culinary delicacy!

I have debated throwing some bagel pizzas in my HT oven a time or two. At 1475F, they should crisp up pretty quick!

 

[JTknives]

Ah yes, Parks 50 and pepperoni... a culinary delicacy!

I have debated throwing some bagel pizzas in my HT oven a time or two. At 1475F, they should crisp up pretty quick!

I warmed up a sub sandwich in my heat treat oven one night, worked rather good.

 

[Stacy E. Apelt - Bladesmith]

When I was in research at Va Chem, we used the analytical lab oven ( basically a big HT oven with super tight regulation) to heat soup and cook pizza. It also was used to dry samples of some pretty nasty things. We never gave it a thought.