Upgrade from forge HT to HT oven question

J

jweber

Joined
Oct 6, 2016
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I've been working with simple carbon steels heat treating in a forge with an oil quench for a couple of years. I'm considering a HT oven for an upgrade, but don't really want the deal with any cryo treatments right now. I'll probably buy some aluminum quench plates to start and air quench.

Two questions:

Is it worth it to get or build a HT oven if I'm not going to go all the way and have a cryo bath available?

What types of steels besides the 1084/1095/O1 etc that I'm using now don't really need a cryo bath? Maybe something stainless?

Thanks
 
A HT oven is almost a requirement if you move beyond 1084. It allows HT with proper temp control and soak times. It also allows multiple blades to be processed at the same time.

Cryo is only needed on certain complex steels with high alloy ( generally stainless steels). It can be replaced with a dry-ice bath in most all cases. If no low temp treatment is used at all, the knives will still be fine, just a point or two lower in hardness that the max attainable. Adjust the temper to deal with that.
 
As long as you stay with High Carbon Steels...W-Series(1-2) !070/1075/1084 the ones you mentioned no need for Cryo or Quench plates. These alloys are all Oil Quench. Air Hardening Steels like Stainless are generally plate quenched and the Cryo Treatment is Generally Beneficial in transforming retained Austenite which is a good thing to finish the Martensite transformation.

As far as Buy or Build a HT Furnace you're going to save money building if you have the time to do all the Fabrication. I built my first one still have it...However I have purchased two others it wasn't worth my time and headaches to have new units to just Plug and Play no trouble shooting and Warranty.

How many blades do you make in a year to justify the price of a heat treat furnace? If you plan to do many stainless like 30-50 blades then yes consider a furnace any less consider sending stainless out for heat treating.
 
Thanks guys. This is a hobby for me. I like doing everything myself. I only have time for about a dozen blades a year although in the last two months I've done a half dozen alone. Building tools is also fun for me, so building one might be enjoyable.
 
jweber said:
Thanks guys. This is a hobby for me. I like doing everything myself. I only have time for about a dozen blades a year although in the last two months I've done a half dozen alone. Building tools is also fun for me, so building one might be enjoyable.
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Build it bigger than you think you will need...even with a DIY build you will be $600 +/- depending on size and controllers it adds up quicker than you think especially if you have to get Soft Firebrick shipped in.
 
Damn, 600 seems a lot. Got my own done for about 200 and i used a way too expencive pid, later on got a 20 buck version from ali express. Also for such small quantities you dont really need firebrick. What i used was fly ash bricks, they will degrade faster, but so far l have used the oven about 10 times and the bticks are still pretty good.
 
jweber said:
I've been working with simple carbon steels heat treating in a forge with an oil quench for a couple of years. I'm considering a HT oven for an upgrade, but don't really want the deal with any cryo treatments right now. I'll probably buy some aluminum quench plates to start and air quench.

Two questions:

Is it worth it to get or build a HT oven if I'm not going to go all the way and have a cryo bath available?

What types of steels besides the 1084/1095/O1 etc that I'm using now don't really need a cryo bath? Maybe something stainless?

Thanks
Click to expand...
I have a question about tempering... I am new to knife making and have just tempered my first knife. I put it in the oven at 400°f for 2 hours. After pulling it out after 2 hours the blade was mostly straw color but then had a purplish patch color almost in the middle of the blade then returned to straw color. Is this bad for the blade? I am worried bc I have spent many hours working on this blade and wanted it to come out right. I hope it isn’t bad for the blade. I’m not sure what to do. Please help!
 
koduu said:
Damn, 600 seems a lot. Got my own done for about 200 and i used a way too expencive pid, later on got a 20 buck version from ali express. Also for such small quantities you dont really need firebrick. What i used was fly ash bricks, they will degrade faster, but so far l have used the oven about 10 times and the bticks are still pretty good.
Click to expand...

I'm in Milwaukee area. I'm lucky because Milwaukee Fire Brick Company is about a mile from where I work. They have a pick up place for insulated fire brick. I can buy one case and just pick it up myself. I'm more concerned about the heating element and getting that right. I also don't weld right now, so I'd have to figure out a case that would work. I might just figure out a way to bolt it together. I built my own grinder without plans, so I'm not too worried.
 
Jeah, there were no fire bricks in my area, and had i shipped them i would have had ti pay a boatload.

About the wire coil, a regular 1 mm kanthal A wire seems to be working fine for me (about an euro per meter). You can coil it by yourself or with a help of a mate. Just make sure you chek that most regions in the coil seem to glow equally when first lighting it up. Also do not test fire it before fitting it to its almost final grooves, it loses a lot of its flex once it has reached its final temperature.
 
jweber said:
I'm in Milwaukee area. I'm lucky because Milwaukee Fire Brick Company is about a mile from where I work. They have a pick up place for insulated fire brick. I can buy one case and just pick it up myself. I'm more concerned about the heating element and getting that right. I also don't weld right now, so I'd have to figure out a case that would work. I might just figure out a way to bolt it together. I built my own grinder without plans, so I'm not too worried.
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I order my Elements from Euclids...All my Furnaces are wired 220v (110v takes forever to heat up). Use 1" angle iron for the frame drill and screw it together. Use 16 gauge sheet metal for the bottom floor to support bricks. There are plenty of DIY Furnace builds you can research for other parts and ideas.
https://www.euclids.com/index.php?cat_name=kiln-elements
 
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