I suspect you COULD, but I suspect there would be some "issues" you'd have to work out along the way.

Something that caught my attention in your post... you mentioned 2" of kawool. I've been seeing that a lot lately, and have to point out that with kawool, more is not necessarily better. In fact, most folks don't realize that when it comes to 1" versus 2" of kawool, 2" does not insulate as well as 1". Kawool is designed to absorb a given amount of heat before it starts reflecting, and the % of heat it reflects is dictated by the thickness...... 2" absorbs more heat before it starts reflecting, and due to it's thickness, reflects a lower percentage of heat. So what does that mean? It means that in the same application, 2" kawool requires more energy (whether that be electricity, propane, natural gas, ect), and reflects a lower percentage of heat then 1" of the same density, which means it requires more energy/fuel to achieve/maintain a given temp with 2" kawool, then it does with 1" (again, assuming they are the same density)

I've asked a number of people why they use 2" of kawool instead of 1"... and the answers I get have lead me to believe that its the old mindset of "More is better"....but that's simply not true when it comes to ceramic fiber blanket such as Kawool.

OK, now that the sermon is over <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />......

No kidding. Thank you. Of course, that was exactly my thinking -- 'more better'.

From the sounds of it, I would be better off with 1" kaowool, and maybe a metrikote IR coating or something along those lines. I still have a bunch left over from making my forge. A little seems to go a long way.

It appears the closest place I can get k23 is about 2 hours away. The price is right at $3 or so a brick, but I haven't the slightest idea how many I'd need.

In using kaowool, my largest issue would be how to attach or suspend the wire without having it short out. Initially I had thought about just going through the wool, through the steel wall or whatever, and using stainless steel zip ties of sorts.

It's still in the early stages yet of planning, but he's got a good portion of the things needed already -- SSR, PID, kanthal etc. We had briefly discussed getting a PID that allowed for a computer to be connected and programs to be ran but we're waiting on a cost estimate.

Jon, thanks for asking this question. I've been wanting to make a heat treat oven for a while. Here are my questions: Has anyone out there made their own heat treatment oven that can be programmed? If so, can you do a WIP or offer information on how? I want one that can handle swords or knives. Does it make more sense to have two different ovens for these applications, or can one be adapted? Are salt pots a better option? If so, any info on their construction?

Thanks!

my largest issue would be how to attach or suspend the wire without having it short out.

I wasn't sure how to say that in my post, but that was the one big "issues" I was thinking about. The other one in my mind would be the "floor"..... I think you could get way with some sort of a "grate" over the kawool, but the difficult part would be finding something that would hold up to the long duration of higher temps.

|quoted:

Jon, thanks for asking this question. I've been wanting to make a heat treat oven for a while. Here are my questions: Has anyone out there made their own heat treatment oven that can be programmed? If so, can you do a WIP or offer information on how? I want one that can handle swords or knives. Does it make more sense to have two different ovens for these applications, or can one be adapted? Are salt pots a better option? If so, any info on their construction?

Thanks!

I had considered a salt pot too, but the more I read about them, the more I learn that they have the potential to be extremely dangerous. More uniform heat vs safety. Maybe I'm making an uneducated statement, but it seems that it's all to easy to create Mount Vesuvius with these.

One other thing though I did (briefly) consider is making a fairly long ribbon burner forge/oven. I'd have to do some research on how they work, but I had thought of laying a goal post style pipe unit down, with burners on each side, similar to what you'd see in secondary burn tubes in a wood stove/furnace.

It would essentially expand on a similar design that I currently use, just spreading out and making more of a uniform heat. I use my little single burner 4" diameter freon forge with a 3" piece of muffler pipe inside it to shield everything from direct flame contact, then just super-heat the chamber inside to my desired temperature. It's not ideal, but it's what I've got to work with right now.

The downside to this of course, is that it's not programmable, propane is more expensive than electricity, and it's easy to overshoot temperatures if you need to ramp. I haven't readily jumped on the idea because it seems money could be better spent using something a little more controllable like an oven.

There's a saying here that I'm trying to keep in mind when considering building this -- "Don't cling to a mistake just because you spent a long time making it."

That being said, I may just need to bite the bullet and buy once/cry once again.

I think the buy versus build thing is always a question in our minds..... at least it always has been for me. Over the years I've learned to look at it from this standpoint...... Can I build one that works as good, or better, for less then I can purchase one?" In some cases we don't have that luxury, because things we need are not commercially available, but for the most part that question will help you decide what to do.

I think we've all been down the road of thinking we would built something, and save a lot of money in the process, but for me it generally turns into way more money and time overall, then if I just would have "sucked it up" and made a purchase to begin with. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Personally, I wouldn't even consider propane for a heat treat oven. There are just too many problems to overcome. It would be a lot like a PID controlled forge.....many people build (or TRY to build) those, and I can't count the number of phone calls and emails I've fielded from folks asking my help because "I can't get it to work right."

While it's nice to have an actual heat treat oven, its far from a necessity, and in some ways I think its more of a hindrance then a help when it comes to carbon/alloy steels that we normally use for forged blades. I never had a heat treat oven in the shop until several years after I'd achieve my MS rating. Prior to that my heat treating was done with the forge, or a torch. Honestly, the ONLY reason I have one now is because I do some stainless folders every now and then.

Looking back at the experiences I've had/seen, often times an individual will seem to have the idea that a heat treat oven is going to be some kind of "magic bullet", and that it will "magically" make every blade come out "right"... when in reality I think it just makes the person(s) BELIEVE everything is good. As with anything we use in our shops, it takes some time, experimentation, and yep....a few wrecked blades, to figure it all out.

In the case of a heat treat oven, unless you just want the experience of building one, I think most folks would be money ahead to just purchase one....but that's just my opinion. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Maybe I am getting too caught up in temperature numbers, soak times, etc.

I normally heat treat all of my things inside my super heated pipe like I mentioned and have a thermometer to gauge temperature (My design is similar to the picture you showed me way back when on KD) but what I'm working on right now (a 5160 cleaver like object) is bigger than my pipe and is literally nearly the width of my forge, so I'm going to have direct flame on the steel which makes me nervous about hot spots, especially where the flame spirals around the chamber. I guess all I can do is keep the steel moving while it soaks and hope for the best.

I figured in an instance like this, an oven would be ideal just for more uniform heat.

Just throwing out the idea, but I had heard of people retrofitting pottery kilns with digital PID's. Not exactly the size I wanted, but I've seen craigslist kilns for less than two hundo. They take more electricity and longer to heat up, but maybe that would be an option in the mean time. It would probably be a step in the right direction at least. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

While it's nice to have an actual heat treat oven, its far from a necessity, and in some ways I think its more of a hindrance then a help when it comes to carbon/alloy steels that we normally use for forged blades. I never had a heat treat oven in the shop until several years after I'd achieve my MS rating. Prior to that my heat treating was done with the forge, or a torch. Honestly, the ONLY reason I have one now is because I do some stainless folders every now and then.

Ed,

Thank you so very much for that comment!

Ed, out of curiosity, how do you do your heat treating without an oven? Simply in a thermometer measured forge? Forgive my ignorance, maybe I can score some tips from you to better my heat treating with what I have and forgo the oven for now.

I guess I just assumed most of you used ovens now since they seem to be so popular amongst the hobby knife makers I've spoken to.

I appreciate the help thus far.

And "other" Ed, I just watched your steel baffle video in your coal forge. I do similar in my propane. Good stuff. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Ed, out of curiosity, how do you do your heat treating without an oven? Simply in a thermometer measured forge? Forgive my ignorance, maybe I can score some tips from you to better my heat treating with what I have and forgo the oven for now.

I guess I just assumed most of you used ovens now since they seem to be so popular amongst the hobby knife makers I've spoken to

I'm gona assume this was directed at me. Actually I use various methods, depending on the steel type, blade type, etc. I didn't mention this anywhere else in this thread, but I also have a salt tank in my shop. I tend to do a lot of differential hardening with the torch, because over the years differential heat treat is what folks have come to expect from me. Although you often see distaste for this method, as with anything, once you understand it, and learn how to use it to your advantage, there's many things you can to with differential heat treating, that no other method will allow. As for it being a "good" or a "bad" method, I think it's all the in the eye of the beholder. It took me through both my JS and MS tests/ratings, and I've won a number of cutting competitions with blades heat treated via the torch method.

When I use the forge for heat treat, its generally with a "pipe" inside the forge, with the blade being heated from the radiant heat inside the pipe. This cuts done considerably on scaling, and with some experience is a very accurate method of heating a blade for the quench.

For the ultimate in control, I personally don't think you can beat the salt tank. Not really any "tricks" to it (beyond building the salt tank setup correctly). All you do is dial in the temp, put the blade in, and watch the temp until it's were you want. The best part about a salt tank is that you can take a blade to nearly finished dimensions and final finish (grit wise). The liquid salt eliminates ALL oxidation, and after the quench, the blade will have a thin layer of solid "salt" on it.....some water and steel wool clean sit up. No scale, no pitting, etc. Very easy to clean up and finish out.

Once reason that I am not a huge fan of the typical heat treat ovens is two fold.... 1. Over the last few years, it seems that every time I read/hear about how somebody does their heat treating with an oven, there is always a "soak" involved. Personally I believe it comes from individual reading a "heat treat recipe" and thinking that the "soak" or "hold" time is the key, and they increase it. I'm always reading on forums where individuals say something such as "Soak for 10mins" or even longer. That's just not a good thing in my book. Any time steel is at or above it's critical temp, grain growth occurs. Once that critical temp is reached, grain starts to grow, and does so exponentially for every second the steel is at or above the critical temp. While the soak is necessary for higher alloy stainless steels, for most of the steels that are commonly used for forged blades, it generally causes more harm then good. Having had a number of individuals come to me for their JS performance test(s), and seeing/studying blades that have failed, those who try to "soak" more often then not fail, and the grain structure(s) in those blades that fail are visibly large and coarse 2. Plain and simple, heat treat ovens produce way more scale then just about any other method (unless you are "wrapping" blades in heat treat foil.

Finally, when it comes to heat treating any steel, something that it seems many individual miss is this..... When a "recipe" calls for a given temp, let's say 1550F..... most folks will dial in their oven or whatever heating method they are using, then bring the blade to that heat (and soak if that's what they choose to do), pull it out, and then go to the quench. When that "recipe" calls for 1550F, it means the steel needs to be at the temp WHEN IT HITS THE QUENCHANT. An example: I've had a number of people contact me because they didn't feel they were getting full hardening on their blade(s). I've learned to have them literally walk me through their entire process, and what I've found is this..... an individual will heat a blade to the specified heat, pull it out, and walk/move several feet away to their quench tank. Therein is the problem....in the time it takes to pull the blade out of the heat source, and move to the quench tank (sometimes 10-20 feet away) the blade has easily dropped well below it's critical temp, possibly a couple hundred degrees below. The solution is to either have the quench tank VERY close to the heat source you're using, or to bump the temp up slightly so that the blade(s) are AT LEAST the recommended critical temp when quenched. This is where "walking the tight rope" comes in. If the blade is at or above critical temp, the grain grows, but if it's not at critical, full hardness isn't achieved. Its up the the individual to experiment, and figure out what he/she wants, and the best way to achieve it. With all the variables from one person's shop to another, there is nothing I can offer that will guarantee a successful hardening/quench every time, but those things I mentioned will hopefully help you realize some of the factors that you might not have otherwise thought about.

EDIT/NOTE: After posting and reading what I'd written, I had to come back and add one more thing after rereading this:

I guess I just assumed most of you used ovens now since they seem to be so popular amongst the hobby knife makers I've spoken to.

I've been at this for pushing 3 decades now, over the last decade, the mentality of the "newer generation" of knifemakers is something along the lines of thinking that experimenting/learning is "old school" and that all they have to do is acquire the latest "tech" or gadget and it will eliminate much of the learning curve involved in knifemaking. Although to a degree it's true that technology is a major help, what must be realized is that its just like any other tool we use....you must understand it, and its strengths/weaknesses to gain the full advantage it offers. In the case of a heat treat oven, I personally believe the reason for their popularity among "hobby" makers is the belief that simply by owning/using one, they are achieving a "better" heat treat. But you still must take the time and effort to understand the tool, and how works to gain any benefit(s) it offers.

Thank you so much for that more in depth information. Very helpful. I'm now feeling a little bit better about my current methods using a pipe inside the forge, and you're really making me re-think the oven for now.

I also rigged a 'baffle plate' instead of a pipe for larger items that don't fit inside the pipe like the one I'm working on now. It's simply to block direct flame contact. I don't know if I can get 1525-1550 this way since essentially flame can't swirl around the chamber and is just hitting a steel plate directly below it, but it's worth trying. Thank you very much for the help so far.

I apologize for coming in with the newer generation knife maker mentality. For hundreds of thousands of years they've made blades without thermometers, ovens, etc. I've watched on video numerous times people quenching in the dark to 'read' the steel and it's color watching the austenite dance across the blade or what not, but unfortunately I haven't the skill and don't know where to begin to even research on how to do that. I assume time will teach me.

I think myself, and many other hobby makers have a fear of failure, and when gifting a blade to someone else, we want to minimize that. Your explanation has helped tremendously though in my decision to hold off for now. As an added bonus, I learned that soaking isn't always a good thing, as I thought grain growth happens above critical temperature, not at critical temperature.

Again, thank you.

|quoted:

Jon, thanks for asking this question. I've been wanting to make a heat treat oven for a while. Here are my questions: Has anyone out there made their own heat treatment oven that can be programmed? If so, can you do a WIP or offer information on how? I want one that can handle swords or knives. Does it make more sense to have two different ovens for these applications, or can one be adapted? Are salt pots a better option? If so, any info on their construction?

Thanks!

Ed it won't fit swords but there are larger ones out there to be had , just have to be ready to snap it up.....

I wanted a secondary oven for tempering , this little beauty ramps up to 2000F faster than my Paragon !

Paid $120 for it (so about $90USD) and $30 in parts to convert to digital for accurate temps , works perfect and holds spot on for as long as you have it programmed......

Very nice find Rob! Thanks for the help...