Grind in done, heat box ready........But.........

L

loosenock

Joined
Jul 10, 2002
Messages
77
Well, after a sabatical of 25 years I have returned to making knifes. Last time I made knifes I always shipped them out at a very high expense to have them treated. I cant afford that this time.

I have ground a boot knife 10" overall, 5" blade out of 7/8" x 1/8" precision ground Crucible 0-1 stock.

The forge is an idea from Wayne Goddard's "$50 knife shop" only I am using a two propane torches instead of one. I have just tested the forge on an old 10" file and was really impressed with the nice consistent and even color I was able to get.

Here is the question. The stock is already in an annealed state. Can I go directly to the hardening quench, or should I normalize, anneal, then quench?

Also, I need recomendations for little smoke, even less fire, oil.

Any help would be greatly appreciated.

Thanks

Loosenock
 
I usually normalize at least once, before hardening, I think as a general rule it is better to normalize. and the more times you normalize the better. I use veggie oil to quench in, I have never had a fire, and the smoke isn't so bad. It smells like someone is cooking.
Kyle Fuglesten
 
Thanks Kyle, I plan on doing the quench next Saturday.

Here's a picture of the one brick, two torch forge...works really well.

Loosenock
 

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Thats a neat little set up. From what I understand, naormalizing a few times befor heat treat will reduce your grain size (good), as well as reducing your chances of warpage in the quench. I normalize all my high-carbon blades three times prior to HT and have had good results. I use plain old Canola oil heated to approx 100 degrees for quenchant, and don't get any flames, just abit of smoke. Good luck.
 
I have a question,your set up is neat but you have the heat going in from only one side won't this cause more heat build up on one side of the blade and cause warpage?:) From what I have seen with carbon blades
uneven heat will cause warpage evertime,am I wrong in my thinking?:confused:
 
To be honest Nathan, I have never heat treated a blade before. I will be able to tell you more after next weekend. Reading Wayne Goddard's book, Wayne never mentioned anything about uneven heat in his one brick forge. The heat sorce comes from only one side on every propane commercial forge I have looked at.

I did heat treat an old file with my set up. I dont think I could have gotten a more even and consistent cherry color on a blade from one of the best commercial units. It was very nice, and I was very pleased.

This forge only cost about me about $20.00. The commercial unit run about $325 and up.

I'm in the process of finding a suitable tank to put the quenching medium in, and I'm going to hit the second hand stores today for a toaster oven for the tempering. I'll let you know how it comes out next weekend.

Thanks for the reply Nathan,

Loosenock
 
Nathan try to find a Ammo can thay come in a lot of
different sizes. The refelection factor will
compensate for the heat source being on one side
only, let the oven heat up befor putting the blade
in to heat treat. Gib
 
Gib. How are you using the ammo can? Are you lining it? I've got an ammo can laying around the shop collecting dust.
 
You will want to normalize it. When in an annealed state the steel has big, fat grain...but it's easy to work with as such. Normalizing will help to take that grain back down to a finer level.

Critical temp for Crucible O1 is listed at 1370F, with your high heat at 1450/1500F. So to get maximum hardness you'll need to get it in that window of 1450-1500F...

If you have all of your shop lights off that will be more of an orange than red. A decent test of this is the magnet trick. Your steel will be at this temp about 1-200 degrees past the steel becoming non-magnetic. So get it to non-magnetic, stick it back in for a short bit and quench.

I would quench it in oil heated to 130-160 degrees and hold it in there until you can hold it in your hand...or close.

Like Gib said, the highly refractive quality of fire brick will cause a pretty decent "even heat" inside that brick. And most ammo cans are supposed to be air tight...so they're not supposed to leak. I've seen several in shops used as quench tanks.

My quench tanks are built from very large, heavy square tubing. The vertical one is full size, the horizontal tank is cut in half. They get to temp very fast with a hot water heater element from Home Depot installed in them. About 4 minutes for 140 degree oil. This idea gets credit from my good friend Mr. Bill Cottrell...a.k.a "plain ol bill"

Good luck and let us know how it goes!
Nick
 
loosenock, is the firebick a "soft white firebrick"? I read somewhere where the soft white firebricks reflect more heat back into the chamber for higher and quicker temperature in the chamber. If it is a soft white firebrick could you tell me where you got it? I have been looking locally, but am having problems finding them here in Columbia, SC. I can find "hard brown firebricks" several places.
 
Nick, thanks for your information. I really appreciate you sharing that with me. I am getting really excited about doing the treatment this weekend.

I went to Saver's (a non-profit second hand store) and bought a Black and Decker toaster oven for $0.99. I played around with it all morning with an oven themometer and got it all dialed in @ 450 degrees.

I live near Denver. I looked in my yellow pages phone book under refractories and located my fire brick. I think it is called K23 or K24....? It is very light in mass. It feels like a block of stryrofoam. The dealer had a broken box of the bricks and I bought 4 broken and two good ones. I think he sold them to me for about $10.00. I ruined several broken ones carving on them. They carve real easy. An old knife, electric drill, rasp file....any thing will carve the brick. The refractory material is super abrasive SO WEAR GLOVES, and if you wear glasses be sure to rinse them off in water before cleaning them, 'cause I tell you this stuff is rough.

I called this place today to see if they had any more bricks. They dont. I could buy a box of 25 bricks for $2.75 a brick. I think I would like to have about 8. I dont need 25. If there are a couple of you who would like to share the rest I would be up to buying a box and split the the box with you. I am a very reputable dealer on ebay (loosenock), check my 134 feedbacks. The cost to you would be actual cost of the bricks plus shipping. I am not interested in making any money on these. They really do work good.

I am thinking about getting these bricks and place them in an ammo box. The bricks are fragile and I think if you cut your holes and lined a big ammo can with bricks you would really have something for about 1/20th the cost of the commercial outfits.

Hope that helps. Thanks for all the replys and interest.

Loosenock
 
So far for 01, I've been using used motor oil. I'd say its probably a mix of 10W30 and 10W40, hard to know for sure since it could have come from various tractors, trucks, cars, etc :) A coffee can about 3/4 full is pretty easy to store if it has a lid, and can do small blades. I warm mine up by sitting it on concrete (outside) and propping a heat gun up to blow on the side of the can towards the bottom.
I get very little smoke and no fire when I drop the blade in.

Run a peice of wire through one of the pin holes in the tang of your knife thats a couple feet long and tie it off. You can hang your blade in the quench that way. Eliminates "going fishing".
 
loosenock, thanks for the tip of where to find the soft firebrick, i called a couple local and found a place that will sell individual ones for $3.80 each, went and got 2 at lunch today. I had been looking at ceramics and brick type places but they never heard of them. But after looking up refractory like you suggested (there are only 2 here), one of them told me where a distributor was local, called them and they set me 2 out so i could pick them up. Again thanks for telling me where to look. :D
 
Tom, I use a 40mm ammo can, it sets on the ground
right next to the forge it is water tight and a lid
that is air tight, good for putting out fires. It is
filled with 50/50 mix of ATF & hyd. oil. Just right
for my large Bowies. Gib
 
The only problem with a small container for the quenchant (oil) is it heats up too much if you want to harden several blades. I've been using a 3" pipe with a base welded on. It holds about 1 gallon and will exceed 120 degrees, my target temp, if I do more than 3 at a time.
Nick, you said that the knife should be kept in the oil until it can be handled. I noticed that Wayne Goddard does the same thing. With 2 people who know lots more than me I hate to argue, but. Once you pass the 'nose' of the hardening curve, usually somewhere between 300 and 650 degrees, further cooling wouldn't have an effect? I've heard that people who use high and low temp salt pots 'cool' at 600 degrees, or there abouts.
Looking for help, Lynn
 
Lynn-

THANK YOU! Absolutely question me, question everything! I will even question something that someone like Don Fogg or Howard Clark says...Yes, they know untold amounts more than I do, but that's how I'll learn is by asking questions and researching!!!

You are right...all you have to do is beat the nose of the hardening curve. Once you get past it, you can hold that steel at a temp in the 400-475 range all day.

At that point you have martensite start (I believe this is the correct term) so that you have beaten the curve, but you have not formed martensite yet.

After quenching in say 400 degree low temp salt, you can take the blade out, straighten it and let it slowly cool through the hardening phase. You won't have to temper it, because it's been hardened with the least amount of stress to the steel possible, and it's formed tempered martensite.

Salt it absolutely the way to go if a guy really wants to be able to tweak his heat-treating. Most everything we achieve in the finished blade will be determined by the austenitizing. Where the steel was when it went into that transformation, how it is treated to that transformation, and how it is froze thereafter.

So, since it sounds like I'm totally contradicting myself :p

The reason I said to keep it in there until he could take it out and grab it: Was so he could easily take it out and examine it, check it for warpage, and hit it with a file to get a rough idea of whether it's hard or not. If it's warped beyond belief or not hard at all, there's no point in going ahead and tempering it. It needs to be re-cycled and re-hardened (IMHO).

Like you said, once it hits that oil, it's hard.

As an aside for those who are interested: Don't think you lose hardness with the low temp salt quench. As long as you beat that curve, your blade is hard. The cool thing about salt is it has a lower viscosity than water. So it is a super "wet" quenchant, that will wrap around a blade like water...minus the vapor jacket you get with water. So you get a super fast acting quench...without the teeth clenching problems with water.

I still play with water though... ;)

Not sorry for being long-winded either :p

Nick

ps, I would rather have someone question me than not. I am not an expert and have volumes more to learn. It's the cumulative effect of researching, applying it, and sharing that let's us push the envelope!!!
 
Hey, the ammo can idea is pretty cool!
I bought a couple of 5.56 ammo cans and use one for storing ammo, cleaning gear and earmuffs for the shooting range trips, and planned to use the other for quenching, but now that I think of it buying a .50 ammo can and lining it with soft firebrick would be great for building a miniforge!

Are them two burners normal hobby store burners for propane?
 
Thanks for the thoughtfull reply, Nick. Yes, martensite is the correct term. It's what most shoot for in longer knives and swords.
Greatfully learning, Lynn
 
Alarion, the two Burners I am using are Bernzomatic JT680. They have air supply holes about half way from the tip and valve. Kinda like the fuel air turbo torches plumbers use. They are really hot. I bought mine from a Home Depot for about $14 ea.

I have a 50 cal ammo can and I think 3 bricks will make a mini forge. You'll have to slice and fill, but these fire brick cut real easy with an old carpenters hand saw.
 
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