Quench tank questions

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Knifemaker
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Knifemaker / Craftsman / Service Provider
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Well, the paragon furnace is on the way. So I want to get started building a heat treating station. I'm going ot use a large ammo cannister for my quench tank. I'm going to sit it on a shelf lover than the furnace and to the left, and I am going to use a hot plate to get it up to 135 degrees. Then on a shelf beneath the furnace, I'm going to put a large toaster oven for immediate tempering.

What I want to do is control the oven and the hot plate with seperate thermocouple circuits so I don't have to worry about monitoring them. Can someone link to a schematic for this? Has anyone done this?

How hot does it get near the furnace? Do I need to build this stand area with fireproof materials, or is plywood good enough? Is there a way to treat the wood so it is more fireproof?
 
Depending on the capacity of the ammo can, a hotplate might be a long wait for the oil to pre-heat. Something that might be of interest....I use 110V hot water heater elements in my quench tank...I have them wired into one of the PID controllers...I just flip a toggle switch and forget about it. In the beginning, before I knew about the PIDs, I just wired them straight, and plugged/unplugged to control the temp.

This might raise a ruckus, but I noticed you mentioned a toaster oven? If you have a heat treat oven, I would use it for tempering....I have NEVER seen a toaster oven that worked well for tempering. They constantly ramp up/down 100-200 degrees, and thats not a good thing when tempering....tempering is all about accuracy.
Now, before folks get all offending, I'm not dogging anyone who uses a toaster oven for tempering....its just not the best thing to use because at best, your just guessing on your tempering temp.
 
I use electric water heater elements and controls. the 220v elements will run on 110 also, done it for years
check the temps with a known pyrometer.
 
Thanks ED. Nuff said. No Toaster. I've been using the household gas oven. I guess I could use the furnace. I just thought it would speed things along to have a seperate tempering device.

PID. Searching.

Thanks Sweeny. CHecking out pyrometers too.
 
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I have been using the house hold oven also, but, I have collected up a element for a large welding rod oven. I am looking for a good sized steel container that I can put some fiberglass insulation and a light gauge metal liner in. I already have a extra pid and thermocouple. Then I will have a digital tempering oven to mount above my HT oven. The HT and tempering steps are so critical to the final product I want to make sure it all goes right Jim
 
Ed, people might get mad at me, too!
I find a toaster oven next to worthless. The heat source is only inches away, too direct for my liking, and fluxuation all over the temp range. Poorly insulated and between cycles can vary waaaaaaaaaay too much.
I use my heat treating oven for controlled soak times and spherodizing/sub-critical annealing. But I do NOT use it for tempering. It seems the mass of the oven actually works against maintaining lower range temps.
Kitchen gas ovens are designed to operate right in the same temp range that we temper a lot of our forging type steels. Mine holds anywhere from 350 to 450 degrees PRECISELY where set.
I'll set three or four seperate thermometers around in the oven cavity and there is almost never more than and 2-3 degree variation.
Neither the heat treating ovens or toaster ovens can do that.
 
Its going to take the Paragon a little while to ramp down from quenching temps. You could use the toaster oven for the first cycle at lower than what you want and give the Paragon a bit of time to cool down, then use it for the last two temper cycles at correct temps.

Jerry
 
The outside of the Paragon does not get very hot at all, but it has istructions to keep it so far away from any wood walls etc.I have mine 1'from the wall and on a metal table. I would follow the instructions. What settings do you guys use for tempering as far as degrees per hour, I have had hell trying to temper in the Paragon due to this setting. If you set the rate to high it over shoots the setpoint and set it to low it cycles constantly and takes forever to get to temp.
 
I use a toaster oven for a first, sort of snap, tempering cycle because my HT oven is still too
hot and I want to get some protection on the just quenched steel. Especially if it's at the end of the day.

Then I do the real tempering at correct temperature in the HT oven after it's cooled down.
 
If you are going to use that oven, what you should do is set it to hold about 600 hundred degrees for an hour or so. Then ramp DOWN to your tempering temp so that the entire oven's mass gets to that point.
When you just set your controller to say 400 degrees, it will read that temp LONG BEFORE the mass of the oven and the atmosphere of the oven gets stabilized at that temp.
Set two or three oven thermometers around in the oven and see what I mean.
I find them undependable at lower temp ranges.
They're great for what they do at the upper limits.
 
Thanks Karl that makes sense. Paragon should have that info in the instructions. It sucks to over heat and have to harden again adjust temps try again and have the same thing happen.
Adam
 
Toaster oven is out for me. I'll just use the household oven for now. Thanks for the 411 guys.

Does anyone have a good source for PID's??
 
my toaster oven is way better than the house oven.
more like 25 degree difference.
I found a nice fluke pyrometer on ebay..
 
I'm pulling the trigger on a Paragon tonight... dang you guys, ya talked me right into it...

What else will I need besides tongs and foil and a rack for the blades? I'm working with 440C and D2 right now so quenching isn't a concern yet...

Karl B. Andersen said:
If you are going to use that oven, what you should do is set it to hold about 600 hundred degrees for an hour or so. Then ramp DOWN to your tempering temp so that the entire oven's mass gets to that point.
Click to expand...

Thank you for that, you just saved a lot of headaches!

One thing that's occurred to me... is this thing going to send my electric bill through the roof? I'll likely only HT a couple/few blades a week at most.
 
You could buy an EvenHeat oven from Tim Zowada cheaper than you can get a Paragon. EvenHeats deal with lower temperatures better, too.

Both home ovens and toaster ovens fluctuate more than a person would ideally like. They both can be set up to dampen temperature swing. We have a toaster oven with a radiant guard between the element and the knife tray. The knife tray has 1/2" of sand/gravel in it. It takes a while for the temperature to stabilize but a high quality oven thermometer shows less than 15F total variation around set point. Wrapping a toaster oven on bottom/back/top with insulation will help but not as much as adding mass. Too much mass (we tried a half size 3000F fire brick) and it takes forever for the oven to stabilize.

A medium sized (counter top type) convection oven would be the best thing a person could temper with. The heat source is remote. Figuring out the amount of mass needed is easy enough. A PID and thermocouple running it would keep temps tighter than actually necessary. Unfortunately, they are not common on the used market and are pricey (my view) as new.

Mike
 
As far as cost goes, the wattage of the unit will tell you what it will cost should be. Lets say you purchased the 1800 watt unit , and plan on running it ten hours a week. That is 18 kilowatt hours a week. Using 10 cents per kilowatt hour as the electric cost ( check your monthly bill for your actual cost), that would mean the oven would consume $1.80 a week.So the monthly bill would go up about $8.

Stacy
 
I know this is coming in kind of late, but I'm going to refence this link for an accurate self built tempering oven http://www.bladeforums.com/forums/showthread.php?t=599423&highlight=PID I followed the directions an tested it with a known mechanical and digital thermometer. It kept the temperature within +/- 5 degrees with some PID tuning during my half hour test after stabilizing. I'm sure it will work even better when I put in a stabalizing plate. :thumbup:

Thanks for something that worked Stacy. :D
 
I temper in a PID-controlled toaster oven.

I have slices of firebrick cross-stacked around the lower elements, to diffuse the heat. I have insulating bricks laid over the top and back as insulation. I have some blocks of 1/2" steel to add thermal mass.

I hold +/- 1°F no problem, from 400° to 700°.
 
patriqq said:
I temper in a PID-controlled toaster oven.

I have slices of firebrick cross-stacked around the lower elements, to diffuse the heat. I have insulating bricks laid over the top and back as insulation. I have some blocks of 1/2" steel to add thermal mass.

I hold +/- 1°F no problem, from 400° to 700°.
Click to expand...

I have the same thing. It works for me.:thumbup:
 
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