How to use a kiln

M

miseryink

Joined
Sep 14, 2012
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I really need help. I was given a brand new knife kiln as a gift. I want to use it for 5160 steel. I am going to use stock removal method and not forging. So I got the steel, I shaped it into a knife, drilled all the holes I wanted and did a rough bevel for the edge. Now what do I do?
Everything I can find about using a kiln to treat 5160 is a mix of forging. I would like one day to forge a blade but for right now I need to work with what I got. Any help would be appreciated. Oh and the kiln does have electric controls and digital pyrometer.
 
Maybe a picture will help out. Or a make and model number.


EDIT: Or are you asking what temperature to treat the blade at?
 
One thing is don't let the kiln come up to temp with the blades in it, wait until it levels out at the target temp, then put them in. Someone can give you specifics on 5160 Heat treat temps I'm sure.
 
I do need to make the question more specific. There are to many terms that I have not learned yet. It gets very confusing reading so many different things from so many different people even on the same steel. I need to know, or where I can find out, what are the steps to take the blade shape and turn it into a working, harden and tempered knife using a kiln only.
 
Don't worry so much about what you are using to heat the steel. Critical temp for your 5160 is 1525 degrees. Basically means the steel needs to be that hot when you dunk it. So heat it up to 1550-1570 to accompdate the heat loss for your kiln to dunk time. Temper can be as low as 350-375 degrees. Look up the spec sheets for the metal to get temperature combinations that will yield different end result harnesses.

Google is your friend, all of the answers are out there. But really just try it, and again, and again, and again. Tweak your recipe each time with the knowledge you have gained and eventually you will know you steel.


Heat treating is far more specific to the metal than it is to te heat source.
 
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Welcome to the forum by the way! Each steel has it's own HT methods, and usually there are a couple schools of thought in how to go about it. 5160 in particular has a lot of opinions but seems to have 2 main schools of thought in how to HT it properly. A great place to start is all the stickies on this forum, there is a vast amount of great information and you'll be a lot more comfortable about the whole idea once you digest it all (may take a while to go through it).

The short answer is heat it up to the proper quenching temperature, and quench 5160 in a medium speed oil (canola is a cheap solution). It will then be very hard and brittle, so you need to temper it back to a lower hardness to add toughness by soaking it at a much lower temp (usually between 300-400f) for a certain length of time (sometimes multiple times at intervals), depending who you ask. The goal being to take out some of the hardness to make it less brittle, while keeping enough to have a hard cutting edge that stays sharp.

If forging the blade to shape, there are sometimes an extra step or two to "relax" the steel before quenching.

Hopefully someone will chime in with specifics, but I highly recommend reading the stickies to start :)
 
Thank you theslacker and mgysthath, just from what both of you said I have the place to start and feel much better about it. It is hard for a new person starting out reading some of the stuff out there. It is almost like there is a great many of awesome knife makers that are full of invaluable information but get caught up in very complex jargon. I am a Chef and if all you know how to do is cook hot pockets in the microwave I would make your head spin with all the words of techniques. I do thank all that helped and welcome anybody else who can chime in, Kyle
 
I've read where you should let the knives heat up with the kiln to temp mgysgthath. Are you just talking about 5160? Does anyone else have a thought on this? Thanks Clay
 
If you put the blade in the kiln as the kiln heats up, you are probably going to overheat the blade before the kiln temp stabilizes. The info on pre heating and ramping up to critical temp is more related to thicker sections than the blades we treat. Put the blade in after the kiln stabilizes at your critical temp, soak for the appropriate time (15 to 45 minutes usually) and then quench. The over heating occurs from the radiant heat from the coils. They have to be hotter than the target temp or they couldn't heat the kiln up. The over heating is one of the reasons that foil wrap welds to blades when using stainless. Learned some of this from reading and some the hard way! If you think about it, the only reason to ramp the blade is to make sure it gets to temp all the way through. The changes occur when the steel is at the critical temp, not before. With the thin sections in a blade, it gets heated through in just a few minutes or less, so no advantage to ramping the blade as the kiln heats.
Chip Kunkle
 
don't need to worry about "Dunk Time". Do not over heat your steel. If you look at the chart on a real fast steel like 1095 where the critical temp is around 1500 you have plenty of time betwen there and 1300 to move the blade to the quench. It is only the part between 1200 and 750 that has to be real fast, about 1 second

5160 is real slow you also have plenty of time to carefully tong a piece of 1525f steel, remove it from the oven and carefully move it to the quench oil where it has almost 5 second to go from 1300 to 750

A piece of steel that is around 1500 is not going to drop below 1300 in dry still for several seconds unless its real cold in your shop. Even then think about it the differnce between 80f and 10f is 70 fr where the steel is 1500f and your worry if from there to 1250
 
Thank you. I am going to guess that it does not matter how long I leave the blade at the right temp as long as it is at least the time suggested, more does not hurt - to little and it does.
 
The kiln came with two extra fire bricks so I cut them to fit the knife in order to position the blade the way I want, what would be the best position to put the knife in the kiln when hardening? Also should I let the fire brick stand heat up in the kiln before I put the knife on it or put both the blade and stand in at the same time?
 
I would have you stand in when the oven heated. Place the blade in spine down, Don't lay it on its side. to easy to warp. Give the 5160 10-15 minutes of soak. The chrome will slow the carbon down. Not as bad as stainless though.
 
miseryink said:
The kiln came with two extra fire bricks so I cut them to fit the knife in order to position the blade the way I want, what would be the best position to put the knife in the kiln when hardening? Also should I let the fire brick stand heat up in the kiln before I put the knife on it or put both the blade and stand in at the same time?
Click to expand...

You must have the Sugar Creek Kiln?

As others have stated, let the kiln come to heat and stabilize before putting your blades in.

Never overshoot your desired temperature to compensate for heat loss moving to the quench. You have time. Critical temperature is when the steel goes into solution, the point at which it "separates back out" is actually lower. No worries.

Excessive soaking can be a problem in some cases so avoid it. It won't benefit the steel.

1525F is a good austenitizing temp for 5160. 15-20minutes soak is plenty at this temp. You could go 1500F with a 45minute soak for good results, too.

Quench in a slow engineered oil or canola as an alternative.

I wouldn't temper any lower than 375F. My 5160 blades are usually done at 400-425F.
 
First of all I want to say thank you for the information and the help. I wonder if I get a little more information from you please, and yes it is a sugar creek kiln. When I temper the blade do I just do it once, I see a lot of people say do it three times? I am going to guess that I need to heat up the oven to 400f and then put the blade in, then pull it out and put it on something that will allow it cool slowly and not pull the heat out to quickly like a cold anvil, correct? Lastly if I use the canola oil to quench should it be unused or used and at somewhat of a room temp 70-80F. Again thank you for all the help, I have learned more from the few people that have responded to this thread than a month of reading. Kyle
 
Kyle... I know it is a lot of work accumulating the knowledge to properly make knives but I assure you, it will be to your benefit to read all you can until you understand it well enough to make educated decisions. This is not meant as an insult but some of the questions you are asking are covered by the most basic of topic searches. We respect your eagerness to get started but many knowledgeable makers have taken the time to put together articles and tutorials all aspects of knifemaking... all we ask is that you appreciate the effort by seeking them out.

Check the "stickies" at the top of the Shop Talk section.

Rick



Edit
Well, now I kinda feel bad. I didn't want to come off as a jerk. I hesitate to put you in this category because you seem like you are making the effort in getting some good equipment and are very respectful in your posting. However, we get a lot of aspiring makers who ask questions before seeking out answers for themselves. Much of the time, it seems that being pointed in the right direction is not what they are looking for... they want answers and they want them, NOW. They don't want to do searches, read threads or pick up books/DVDs. Generous members end up spoon feeding these individuals, day after day, week after week, until they begin to not even bother opening "newbie" threads. As for the spoonfed individuals, what happens is that they never truly learn the skill and more often than not, choose methods by popularity instead of fact based reasoning.

As I have said, I hesitate to put you into this category as you are new to this forum and must be terribly excited to get going with your kiln. I simply want to make you aware of an all-too-familiar pattern that is easy to fall into.

To answer your questions...

Temper at least twice for 2hrs each cycle. For plain carbon steel, it is beneficial to water quench after each cycle. This helps to eliminate unwanted precipitations and saves a bunch of time.

Use fresh oil and warm it up to 100-130F (you should be able to dip you finger into it for a few seconds without screaming:thumbup:)
 
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Honestly I didn't think you where being a jerk. I understand where you are coming from. The truth is I have been reading everything I can for quite some time, just about a year. It took me a month of studying metals to pick just one to start with, that was back in June. I picked it cause of its wide range of uses and the fact that It can be found in specific old truck leaf springs. Little did I know how hard finding those would be, so two days ago I bought some from Jantz supply. The kiln came from my family as a present cause they have seen how I have been working at this. I absolutely know that I was asking basic questions but they were things I really could not seem to lock down from all my reading. Most of what I find is information on using a forge to treat everything and some also with kilns. I can't afford to spend the kind of money some of these things cost, I built a very primitive forge with a hair dryer, 5 gallon metal bucket and masonry cement. My belt sander is a 1"x30" from harbor freight. serves me well and not complaining at all, I do believe it is less about the equipment and more about the skills of the person. Sorry didn't mean for this to be so long, just wanted to explain myself some. I really have not jumped into this and expect to be making knives to sell anytime soon. I have been making custom crochet hooks for a while now so I could learn how to shape wood and make good handles, good skill for knife making but I am teaching myself something for knife making and not even making knives. I do thank you for the edit on your post and your time and patience, Kyle.
 
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