Accurate, low-cost tempering oven?

J

JoshEarl

Joined
Sep 30, 2007
Messages
197
The little toaster oven I've been using for tempering has started shutting itself off at random times, and I'm about ready to go all Office Space on it. When that happens, I'll need a new tempering oven. :)

Remembering the scorn that Kevin Cashen heaps on toaster ovens, I wonder if there's something better out there short of a heat-treating oven. I'm quite comfortable doing heat-treatments on carbon steel blades using my forge, so I don't want to buy a Paragon or something like that.

Using the kitchen oven isn't an option, either. My wife is very tolerant of my hobby, but I think the smell of baking Parks #50 would be pushing things.

Is there a really good toaster oven I could invest in, or maybe a low-end kiln or something? I'd like to stay under $200 or so and have the oven be fairly compact.

Thanks for the help,
Josh
 
check out Best Buy - look for "Euro-something" oven - these are X-large, dirt cheap and last forever.. If you're after extreme accuracy, you can install your own TC and PID+SSR to control the temp, but it is an overkill IMO
 
TRy the surplus sales department at your local university or college. They may have several different kinds of ovens that could serve your tempering.

Also, I'm not a welder, but do welding rod ovens have any degree of accuracy?

Rob!
 
J.E.
Hit your local Goodwill, Good Samaritan or thrift stores. Look for a rotisserie oven. Big, lots of heat and cheap. Not accurate temp. setting so buy a oven thermometer and go for it. Works for me.
 
I wonder how hard it would be to build a low temp oven with a pid and a thermocouple for tempering ? I know a few people have built their own heat treat oven....Hmmm
 
Any roaster oven, toaster oven, etc. can be PID controlled. The SSCR can be mounted on a heat sink and can easily control 15 amps or more.
Another idea is what many full time makers do. Buy a regular oven ( maybe even an in-wall or above range type) at the local flea market, or the good will. Used ovens are often almost free. I almost bought a brand new above range electric oven three weeks ago, but talked myself out of it )I don't really need one) .It was $75.

Rocketman - It would be fairly cheap. I would use a dryer element. The walls could be standard thermo board from Darren Ellis.

Stacy
 
Here's a tutorial that I based my HT oven after:

http://www.britishblades.com/home/articles.php?action=show&showarticle=31

Here's a place that you can get the elements and controllers from:

http://www.budgetcastingsupply.com/Heating_Elements_Controllers.php

You can also look for pid controllers on ebay. The setup above is a bit overkill for a tempering oven, but you could scale it back a bit and have a really accurate tempering oven. The oven I built reaces 1500 degrees in just over 5 minutes with a tight fit and high-temp tadpole gasket and stainless strapping to seal the door. Slower up to 2000. K-type thermocouples can be found on ebay as well for the pid.

--nathan
 
bladsmth said:
Any roaster oven, toaster oven, etc. can be PID controlled. The SSCR can be mounted on a heat sink and can easily control 15 amps or more.
Another idea is what many full time makers do. Buy a regular oven ( maybe even an in-wall or above range type) at the local flea market, or the good will. Used ovens are often almost free. I almost bought a brand new above range electric oven three weeks ago, but talked myself out of it )I don't really need one) .It was $75.

Stacy
Click to expand...

If you have 220V service available, this is a great idea. :thumbup: We can barely give away built-in ovens that aren't high-end brands. In fact, I think we're trying to give away a couple right now. Check out architectural salvage shops and used appliance dealers.

JR
 
JoshEarl said:
...Remembering the scorn that Kevin Cashen heaps on toaster ovens, I wonder if there's something better out there short of a heat-treating oven...
Click to expand...

More importantly would be the reasons for my preferrences, my feelings aren't any more valid than any body elses. Just if I have my choice for tempering I would go in the following order-

Low temp salts
A larger finely controlled kiln/oven
A kitchen oven that has been verified for temperature
A small kiln or oven
A toaster oven
A torch, a campfire or BBQ grill;).

Anything can be done but some things I leave as a last resort for my own peace of mind:)
 
Kevin, where does the radiator of my 4x4 fit into that scheme? :)

I fully appreciate that you have good reason whenever you heap scorn on something. :)

Some comments you made earlier were what got me thinking about this. My toaster oven seems pretty inaccurate; I think it's cycling about 50 degrees right now. When I first got it (used, $10, so no great loss) it seemed like it was dead on. My kitchen oven is just about as bad, so I'm hunting for other options.

Josh
 
What burns me is you spend $1600 on a high-end HT oven and can't even use it for the tempering because of the thermal rebound. I'm afraid the toaster oven will be tempering my blades for the forseeable future...

P.S. Can anyone tell me if the Even-Heat ovens can be ramped down quick enough (without temp rebound) to be used after the HT for tempering? Their various steel HT instructions act like it can be done, but I can't understand why Paragon ovens would be so highly recommended if an Even-Heat could do the tempering as well as HT. WTH?

Regards,

Dave
 
I have a couple of devices I temper with (but I'd really like a hot salt tank set-up). I bought a toaster oven from WallyWorld once, put a seperate thermometer in it, and the readings was so far off, that I bought a second thermometer, and it was off also. I didn't know which of the three to watch, so I use it now to warm pasteries at the shop.
I bought an oven called a "Swirlair" years and years ago. It was one of those 30 minute info-mercials. I decided to watch it because I was learning how to price things I made from wood, so I wanted to see how the experts did it. I wasn't going to be taken in by this scam mind you, I was mirely wanting to see how the big boys suckered people in to buy their junk. About 30 minutes later, I was running through the house looking for my wallet so that I could order one of the darn things. Yep, the "SwirlAir". Not all that big, but you could roast a side of beef or 12 turkeys with it. The first time my wife saw it when it got delivered, she made me put it out in the garage.
So, years later, I'm needing a oven of sorts to temper steel. Since the Wally World one didn't work, I decided to try the SwirlAir. Hey brothers and sisters, this thing tempers great, and all three indicators are right on. It circulates hot air around, to cook your turkey fast, and all the way through. I use the normal
heat treat temps, and so far I've been very pleased. The hot air contacts everypart of the blade instantly, and circulates around it right at the 400 or whatever degrees.
Down side, the company went belly-up right after all those commercials, because fools like me didn't buy enough of them......but I got mine :o)
Salt tanks for HT and temper are next on my list, as I believe it's truly the most accurate way to go. I don't like the thought of the corrosive salts turning everything rusty in the shop, maybe Kevin uses a special room for this.
 
rhrocker said:
I have a couple of devices I temper with (but I'd really like a hot salt tank set-up). I bought a toaster oven from WallyWorld once, put a seperate thermometer in it, and the readings was so far off, that I bought a second thermometer, and it was off also. I didn't know which of the three to watch, so I use it now to warm pasteries at the shop.
I bought an oven called a "Swirlair" years and years ago. It was one of those 30 minute info-mercials. I decided to watch it because I was learning how to price things I made from wood, so I wanted to see how the experts did it. I wasn't going to be taken in by this scam mind you, I was mirely wanting to see how the big boys suckered people in to buy their junk. About 30 minutes later, I was running through the house looking for my wallet so that I could order one of the darn things. Yep, the "SwirlAir". Not all that big, but you could roast a side of beef or 12 turkeys with it. The first time my wife saw it when it got delivered, she made me put it out in the garage.
So, years later, I'm needing a oven of sorts to temper steel. Since the Wally World one didn't work, I decided to try the SwirlAir. Hey brothers and sisters, this thing tempers great, and all three indicators are right on. It circulates hot air around, to cook your turkey fast, and all the way through. I use the normal
heat treat temps, and so far I've been very pleased. The hot air contacts everypart of the blade instantly, and circulates around it right at the 400 or whatever degrees.
Down side, the company went belly-up right after all those commercials, because fools like me didn't buy enough of them......but I got mine :o)
Salt tanks for HT and temper are next on my list, as I believe it's truly the most accurate way to go. I don't like the thought of the corrosive salts turning everything rusty in the shop, maybe Kevin uses a special room for this.
Click to expand...

So, basically, great story but the rest of us are out of luck. :)

That sounds like an interesting idea; maybe there's something similar being manufactured today.

Josh
 
Robert, is that what is called a convection oven?? My wife has been trying to push on eon me for a while. Is yours fairly consistent? bruce
 
One of the points made in Tool Steel Simplified is that tempering ovens with internal fans work much better. Sounds like a convection oven to me.
 
I understand they sold 10's of 1,000's of these things to housewives, and one man all across the nation. After that first flurry of business, apparently they took the money and ran. There has to be bunches of them in peoples garages and septic tanks. Try eBay, I'd bet anything that there are some on there. I go in lots of 2nd hand shops several times a year when I go to the coast to fish and eat. I've seen some in those shops, but I'd just stop and look at them, smiling, then she would get me by the ear and drag me off. I'll see what I can find.
 
If you ever run into a Farberware 'Turbo Oven' (no kiddin', that's the name), snatch it up. It's got a single top-mounted fan, a large door, large interior, and it seems to keep really consistent temps. Picked one up to replace my old beater toaster oven at the local Salvation Army store. Cost all of $12.
-Mark
 
Dave I use my evenheat to temper but it does take about 45 min to come down to 400 deg. I use a cheap toaster oven set at 300 deg. that has a coule of pieces of ceramic tile inside,I turn it on about 15 min before my hardening cycle ends, out of the evenheat onto the quenchplates,down to room temp unwrap and check for warp.into the toasteroven,leave the door open on the evenheat and let it cool in abot 45 min I close the door and check temp, pull the blades out back onto the quench plates to room temp then into the evenheat for 2 hrs. Back to room temp and then back into the evenheat for another 2 hrs.
 
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