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Heat treating my first blade - wadebevan - 03-20-2017
Hello all,
I just wanted to get a thread started on heat treating.
This is one area that the internet seems to have a lot of conflicting opinions.
If you read enough, you can get a pretty good idea about the process, and what parameters are involved.
For my first blade, I was going to outsource the HT, but, I decided that it was better to learn by doing, than having someone else do it.
I bought a used pottery kiln for a pretty decent price, and promptly brought it to the shop and cut a 6" hole in the lid. (It was a top loader)
After shaping a couple of fire bricks to cover the hole when heating, I started to test with some scraps.
Electric kilns take a long time to get to 1500F!
And cheap thermocouples catch fire around 700F!
How do you measure temperature?
Thermocouple, magnet or other?
What do you use for quench oil?
What temp do you heat your quench oil to, if you do?
Just trying to learn as much as I can before starting blade #2.
Thanks,
TW.
RE: Heat treating my first blade - Mark Reich - 03-21-2017
(03-20-2017, 02:44 PM)wadebevan Wrote: Hello all,
I just wanted to get a thread started on heat treating.
This is one area that the internet seems to have a lot of conflicting opinions.
If you read enough, you can get a pretty good idea about the process, and what parameters are involved.
For my first blade, I was going to outsource the HT, but, I decided that it was better to learn by doing, than having someone else do it.
I bought a used pottery kiln for a pretty decent price, and promptly brought it to the shop and cut a 6" hole in the lid. (It was a top loader)
After shaping a couple of fire bricks to cover the hole when heating, I started to test with some scraps.
Electric kilns take a long time to get to 1500F!
And cheap thermocouples catch fire around 700F!
How do you measure temperature?
Thermocouple, magnet or other?
What do you use for quench oil?
What temp do you heat your quench oil to, if you do?
Just trying to learn as much as I can before starting blade #2.
Thanks,
TW.
I rely heavily on good heat treating ovens. They're so easy to run.
I still use magnets when I'm hardening a blade with an acetylene torch.
For precise temperatures, I use a couple of Omega hand held units with 18" long, K type thermocouple probes. The most basic hand held that measures to 2000*F would be fine. If you want welding temps of 2500-2600*F, it's more expensive.
Bigger diameter probes last longer for measuring hot stuff, but you still end up replacing them. Nature of the beast.
I use Park 50 and Park AAA quench oil, and heat it to the temperature that gives me a harder blade (hotter oil cools faster) or tougher blade with slower oil (which is generally also easier to use).
I hear people use vegetable oil all the time, but heat treat is Not the Place for Mistakes.
If you have a few blades and want the HT to be Perfect, send them to Brad Stallsmith at Peters HT.
Hope that helps
RE: Heat treating my first blade - Bobbo - 03-24-2017
This is all very interesting. I'm still trying to figure out how to sharpen an edge and you guys are building them. I have no concept of what your hardening ovens or torches/process look like. Would you be kind enough to stick up some pictures so that I can get my arms around this a little better? Would be much appreciated.
RE: Heat treating my first blade - Mark Reich - 03-25-2017
As you're aware, heat treating is an enormous subject. Specific heat treat information is readily available. You read as much as you can stand, then try to find some middle ground from which to begin.
This will help more than anything I could possibly say in a post.
Here's a Link to a lot of general information on heat treating.
Here's a Link to a great HT reference. Lots of guys look here first, because Kevin put a lot of information in one, easy to find, place.
Here's a Link to the interactive steel chart. There's a little search bar at the top of the chart so you can type in any steel you want, and you'll get the alloying elements.
I'll try to field questions.
RE: Heat treating my first blade - Mark Reich - 03-25-2017
Here is my cart of heat treating equipment. I should have removed the Mapp torches and replaced them with the two small burners I just got from Rex Price's son, Jared, at; hybridburners.com
The difference is about 1,000*F/burner!
On top is an "18 inch Evenheat" (the exterior measurement is 18", usable length about 10", and it's UNeven heat)
Next, we have a real kiln. A new (as in "the first one sold") 24" Paragon. It's 24" on the inside, and has elements on the ceiling, so I can go at an angle and get over 24". Touch screen control like never before. I'm the new Paragon spokesman.
Down below is an industrial, cast iron, OMG, propane double burner, with 5 gallons of Park quench oil on each burner.
The space was "to fit".... without the LP tank or stack of firebrick.
![[Image: IMG_0656_zpsfyna2fyk.jpg]](http://i260.photobucket.com/albums/ii10/ytreich/IMG_0656_zpsfyna2fyk.jpg)
![[Image: IMG_0654_zpsihjvrsfe.jpg]](http://i260.photobucket.com/albums/ii10/ytreich/IMG_0654_zpsihjvrsfe.jpg)
![[Image: IMG_0651_zpskv7qj2ci.jpg]](http://i260.photobucket.com/albums/ii10/ytreich/IMG_0651_zpskv7qj2ci.jpg)
RE: Heat treating my first blade - wadebevan - 04-28-2017
Hi all,
I have a question that has been bugging me since my first heat treat, and I am about to do my second.
Here is the question:
How does the time going from oven to quench oil effect the HT overall?
This seems to be a critical step, but, I have not come across much info in my reading (not saying that info is not out there).
My thought is that this time should be minimized as much as possible, but, it isn't eliminated.
Any thoughts from the group?
Thanks,
Wade.
RE: Heat treating my first blade - Mark Reich - 05-02-2017
I can only say that everyone tries to get their knife from the kiln to the quench ASAP, which is just quick enough.
If you've seen people quench a blade on tv, and they pull this big fireball out of the oil, remember one thing- That's retarded. The blade is obviously still WAY too hot. The purpose of the exercise is to cool the blade. For this, it needs to stay in the oil, and it needs to keep moving briskly forward and back. Not side to side or in circles, which usually warps the blade.
I suggest two things. First you'll want to find an extra long needle nose pliers with a 90* bend on the tips. You'll find it's much more secure than a regular extra long needle nose, and much easier to feel and control than a heavy set of tongs.
Next, just practice with a cold kiln. Learn how to position the blade for easy grabbing. Have everything situated handily. Concentrate on being smooth and efficient.
When we practice any kind of shooting, we always think along these lines; "Slow is smooth, smooth is fast". Practice being smooth, slowly and very deliberately. You'll end up going fast.
RE: Heat treating my first blade - wadebevan - 05-02-2017
Thanks Mark.
When I did my first blade, I practiced with a cold kiln.
Thought it through after sleeping on it, then practiced some more before going 'hot'.
I used a piece of 1/16" stainless welding rod to hook through a small hole in the tang.
The whole thing was hanging in the heat, and pulling it out and going to the quench was maybe 2 seconds.
It also allowed me to drop straight in as it was hanging loosely and gravity helped out as long as I didn't 'swing' the blade.
I then just raised it up and down and forward and back. (My quench pot is pretty deep)
No fireball. Not even much smoke.
I've done some reading about stainless steel 'wraps' around blades in order to keep some of that heat in during the transfer (as well as limiting oxygen exposure).
Seems that it could help, some.
I guess what I am wondering about is what effects does that 1-3 seconds have on the HT overall?
I'm probably overthinking it
Wade.
RE: Heat treating my first blade - Ken S - 05-03-2017
During my career as a telephone repair tech, I occasionally worked in a factory building formerly occupied by a company which manufactured large overhead cranes. The current tenant was a drop forging company. My trouble was located directly above a very large hammer forging machine. A piece of steel almost a foot square by several feet long was being hammered by a power hammer. The steel was orange hot. The heat had melted the telephone cable located directly above.
It was fascinating to watch. (I returned another day when the machine was not in use to complete the job....)
Ken
RE: Heat treating my first blade - Mark Reich - 05-04-2017
Mr. Ken, that sounds like it would have been fun to watch! Do you have any idea what size the power hammer was?
Mr. Wade, it really depends on the thickness of the blade. Especially how thick your edge is.
Kitchen knives can be tricky. You need to be in the 1 second range. I was just discussing this with another bladesmith recently. He was having trouble because his grind was crazy thin. Couldn't get it into the quench fast enough to full harden the edge.
If you leave yourself .010- .015" you have to be fast. If you leave twice that you won't have any problem.
The guys who wrap their blades are usually quenching powder stainless blades between aluminum plates.
I send them to Peters. Brad wants the edges .010" max. His HT is absolutely perfect every single time. As long as I'm doing 50 blades at a time, it's super cost effective.