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5:20 pm
May 13, 2010
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I currently sub out a lot of my heat treating and while the cost does not bother me for critical things such as lifting devices etc. I make a heavy scraper/chisel blade that gets hardened to 241-277bhn and the heat treating works out to about $7.50ea. which is cheap if I were to try tempering them in the forge, as well I spend about 1/2hr dropping them off and the same picking them up.
I have looked at the heat treating ovens such as the Paragon and they are reasonably priced and while I would probably have to do them in two batches it would work fairly well. A couple of months ago I talked to the salesman at a company that makes new industrial heat treatment furnaces and sells used ones. He told me that tempering should be done in a separate tempering furnace that has a fan to circulate the air and prevent hot and cold spots. What he recommended was what he called an over under furnace. Where there are two furnaces, one high temperature for hardening and a second for tempering. While I am sure this is better it is more money than I am prepared to spend right now and I don't have the space for a unit that big.
Those of you with the knifemaking type ovens something like this http://www.paragonweb.com/HT14D.cfm Have you found problems with hot and cold spots while tempering?
6:52 pm
NWBA Member
August 7, 2010
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Good Morning,
I found 'A Home Built Heat Treatment Furnace" on iforgeiron.com In the article, there is a link to http://www.budgetcastingsupply.com in California.
They seem to have all the components and digital controllers to make your own oven.
Enjoy.
As long as we are above our shoes, We know where we are.:happy:
8:31 pm
March 18, 2010
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At 30 amp I guess it's made for an electric HT furnace. Suppose you could hook it up to blower and a solenoid gas valve. Might want to have a pilot light with that.
“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~
8:37 pm
March 18, 2010
Offline
Yes, electric furnaces can have varying temperatures. You can put a little propeller through the wall in one corner to push the air around, think tornado.
“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~
3:30 am
May 13, 2010
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Thanks guys, I was leaning towards just buying a furnace. I have enough projects to build for the shop and I am not sure I would be saving all that much by the time I buy a controller, elements, kaowool or insulating brick and get someone with a brake to do my sheet metal bends or spend the time to weld all the corners. A small propeller with an external motor is a good idea. It is something I could easily add for tempering.
4:28 am
September 23, 2011
Offline
I have an evenheat HT 22. I haven't noticed hot and cold spots. It only has one thermometer in the top center. I watch the readout screen some times and it never goes over or under a few degrees. The one thing is that they do take a while to cool down. I use and air hardening steel and after heating to a hardening temp, and I take them out to air quench, I put a large fan in front of the oven to cool it down. I leave it there until its way below the tempering temp, because as soon as I close the door it will jump way past the desired temp. But once it cools down it will stay consistent...don't know if that helps
Saign
---------------
http://www.saignc.com
5:02 am
March 18, 2010
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Wow Saign, thanks, I wasn't aware of that company. Very reasonably priced and good looking machines.
http://www.evenheat-kiln.com/h...../htseries/
[Image Can Not Be Found]
“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~
6:30 pm
September 23, 2011
Offline
I actually have the KF 22.5 I noticed after checking out the link you posted. Its a good machine the walls are made of thin stainless, and the door could be a little more sturdy. But overall I'm satisfied. If your looking to buy one call trugrit http://www.trugrit.com/
They were my local knife making supply in CA and gave me a much better price than anywhere else. They don't list the price online, you have to call them but they're really nice and will give you a great deal.
Saign
---------------
http://www.saignc.com
6:44 am
May 18, 2010
Offline
We have always used a lecky furnace to both harden and temper with and have not had any cold spots nor hard spots.
We tried the fan thing as Grant suggested but the heat from the furnace melted all the plastic.
7:14 pm
NWBA Member
August 1, 2010
Offline
I see some ovens speced at 2000F, others at 2200F or higher. What applications actually require more than 2000F?
7:02 am
NWBA Member
August 8, 2010
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I have the Evenheat KF as well. Never any problem with different temps in mine. I do soak at temp for 15 minutes before I open the oven. I use the stainless tool wrap to keep the blades clean.
The first time you open the oven door at temp is kinda exciting- quite a heat blast all at once. I bought a pair of the heavy glass-blower's gloves 🙂
Dave
No one really listens to anyone else, and if you try it for a while you'll see why.
- Mignon McLaughlin
7:26 am
September 23, 2011
Offline
bryanwi;13472 wrote: I see some ovens speced at 2000F, others at 2200F or higher. What applications actually require more than 2000F?
Some high speed steel alloys require higher temps
Saign
---------------
http://www.saignc.com
7:37 am
March 18, 2010
Offline
Yeah, if you just have a few pieces and place them centrally, it's probably not a problem. With no air movement there will be some potential for unevenness. I have a largish electric HT oven about 18" deep X 24" wide X 20" high. When I temper a large number of parts (50-100) I find that even with a good soak that the temper color they show varies some. I think anything to stir the air a little would help.
OBTW: That oven has elements on all sides, even in the door.
“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~
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