DIY sword tempering oven

[Tony Park]

My google fu is weaker as I age. Also, I tried searching here with not too much luck frankly. I'm surprised something didnt pop up though.

I've decided this has been so much fun, revisiting my martial arts youth of 25 years ago and making blades that I've decided to become very, very serious about this.

I called my local spring shop(because Stacy told me to) because they've already committed to giving me all the scrap 5160 I could ever use. I have a ton from them in my back yard.

They won't temper for me though because they don't really wanna get involved.

I also don't want to push. They have been wonderful. 5160 makes great filipino style blades and so I can make them one... its short enough to fit in the kitchen oven.

But I love katanas. I love war katanas specifically and I love movie swords. Long blades.

I also want more control from start to finish.

Finally, there is some sense of urgency. My girlfriend is a teacher and we live in a right to work(right to get fired at any time for any reason state: Arizona). She has strong religious convictions and doesn't want to get the vaccine. They are mandating it. She works for a charter school which has even less employment law protection. So they are going to fire her unless, by the grace of God, the covid count gets even more high so that they can't open up the school in a month.

So I want to make a few blades to supplement my income. Swords sell better, I believe, than knives. Even if I only make an extra something a month to have some fun outside, i think that would be great.

So can we start this as a thread on how to make a device that can temper long swords?

PS: Stacy has been unimaginably helpful since I've come here so I just wanted to take time out to thank him.

 

[Sam Salvati]

Jeeze there’s a lot to unpack here.

 

[Stacy E. Apelt - Bladesmith]

I will be the one to point out that you are just starting to make your first sword and are bouncing all over the place about materials, methods, and advanced techniques. I would learn to make swords well, which isn't a quick thing, before trying to go commercial.

A simple sword tempering oven can be built with insulation board, a roll of metal duct tape, foil backed insulation, and a couple of strip heating elements, plus a simple temperature controller and TC.
Send me an email, as I have several spare temperature controllers for a tempering oven.

Just an FYI, with your membership level you can't discuss selling and prices. Please edit that info out of your post.

Also, I understand your situation with the girlfriend, but this is not the sub-forum for that, either.

 

[Tony Park]

I will be the one to point out that you are just starting to make your first sword and are bouncing all over the place about materials, methods, and advanced techniques. I would learn to make swords well, which isn't a quick thing, before trying to go commercial.

A simple sword tempering oven can be built with gypsum board, a roll of metal duct tape, foil backed insulation, and a couple of strip heating elements, plus a simple temperature controller and TC.
Send me an email, as I have several spare temperature controllers for a tempering oven.

Just an FYI, with your membership level you can't discuss selling and prices. Please edit that info out of your post.

Also, I understand your situation with the girlfriend, but this is not the sub-forum for that, either.

I will be the one to point out that you are just starting to make your first sword and are bouncing all over the place about materials, methods, and advanced techniques. I would learn to make swords well, which isn't a quick thing, before trying to go commercial.

A simple sword tempering oven can be built with gypsum board, a roll of metal duct tape, foil backed insulation, and a couple of strip heating elements, plus a simple temperature controller and TC.
Send me an email, as I have several spare temperature controllers for a tempering oven.

Just an FYI, with your membership level you can't discuss selling and prices. Please edit that info out of your post.

Also, I understand your situation with the girlfriend, but this is not the sub-forum for that, either.

Stacy. This isn't the first sword I've made. But it is the first stock removal blade. Admittedly I am 25 years from my last.

Anything worth doing well, is, paradoxically, worth doing poorly. That's a ridiculously hard lesson for me to have learned over my life. There's a wonderful video by Jordan Peterson on the subject. Speaking of YouTube. There are scores, dozen, horrible makers with no eye for design making tons of money, on youtube, in swords. Many of them make 20-40k a year selling the blades plus a bit from youtube itself.

I'm certainly not saying I'm going to make this my career. But I am saying that someone who lived in Asia and has made swords in the past can do better. I've built guitars, cars and other things. I have an eye for proportion.

Stacy. You've made some comments that at once rankle me and also make me feel proud.

I love it when old timers in a craft accuse me of "jumping all over the place"(like a kid)

It means I'm doing something right. Its exactly how kids learn. That's why they are smarter than adults. Because they are fearless and care very little about doing something badly. They are flexible where adults are recalcitrant.

Where adults win out is they know where major safety pitfalls might be.

I'll never brag about being some great swordsmith. What I am great at, is learning things.

By day I'm an investment firm owner. Its a very small firm, but its mine. 11 years ago I left corporate finance dividing my time between corporate audit and process improvement.

Process improvement. So when you say "jumping around" I say tools acquisition. Mental tools. Gathering territory.

What would be very cool is if this thread turned into a repository for how to make a simple, RELIABLE, REPEATABLE, CONTROLLABLE diy tempering oven for swords.

Because I haven't seen that out there yet. What I'm not willing to do is blowtorch blades or put blades cattywampus in my kitchen oven and flip it around.

That may be the low-hanging fruit way of doing something, but I'm certain we are all more capable of finding a more reliable, permanent solution than that.

For example. Is there such a device that both gives off heat or electric current but also regulates it and measures temperature? I saw your mention of an email. I'll do that.

Lastly. Ill try to answer the bit about jobs and why the suddenness of it all.

The cost of acquisition of a new client, via advertising, wining and dining, gifts and more is about 5k. Im really crap at marketing and so is the rest of my industry. I'll never get a new client in time to replace my gals income.

I only mention my gal because frankly, I didn't want to get derailed into this discussion and wanted a quick point to a thread which I feel should, which I am surprised doesn't already, exist.

With the exception of of a few things, I have everything I need to make most blades id want to make. My main thing missing is a tempering oven.

So I hope that explains things better. I'll never stop asking youngish sounding questions or bouncing around asking stupid ones.

Experience tells me that those questions are always the right ones to ask.

 

[Stacy E. Apelt - Bladesmith]

Tony, I am so sorry! My error, Somehow I was thinking you were a fellow who had just sent me an email on making his first sword.

If you decide to build a tempering oven, I will still be glad to send you a controller and TC . Send me an email.

 

[Tony Park]

N

Tony, I am so sorry! My error, Somehow I was thinking you were a fellow who had just sent me an email on making his first sword.

If you decide to build a tempering oven, I will still be glad to send you a controller and TC . Send me an email.

No no, not me. At least not yet. By the by you are an incredibly helpful fount of wisdom on the subject which is why I plan to lean on you heavily.

I'm also not dumb enough to think I know it all. I surely don't. Not about this subject.

Investments and tax and asset protection from lawsuits? I'm very much an expert in those areas. Feel free to reach out, gratis, for some help. I'd be honored.

I am emailing you now.

 

[Stacy E. Apelt - Bladesmith]

Got your email.

 

[Natlek]

So can we start this as a thread on how to make a device that can temper long swords?

This is your tempering oven for long swords .At least that i would make soon ...........it couldn’t be simpler than this . Easy , cheap, and fast build with little tool needed....length of oven as much as you want .

 

[Tony Park]

This is your tempering oven for long swords .At least that i would make soon ...........it couldn’t be simpler than this . Easy , cheap, and fast build with little tool needed....length of oven as much as you want .

Wow natlek, this is a real gift to me. Thanks so much. is there a reason the red element lines dont extend past the thermocouple?

what are the tubes made of? I suspect steel but maybe only the inner tube is steel, then insulating kaowool, then something like adobe/concrete ? or something? The outer steel pipe is probably going to be very expensive.

Do the heating elements need to be as long as the blades I treat or would shorter do? Is there a recommended size.

How much insulation thickness should i get?

Stacy has been incredibly kind to send me parts. Where is the rest of the stuff available? who is the best/least expensive to buy from?

Thank you so much for this. Nothing like a map to bring the territory closer to home.

Tony

 

[Rick Marchand]

Sorry, I need to ask... by "tempering" you mean the process AFTER hardening, right? I take it you have something to harden your swords in already? Forge, salt pot, high temp oven?
Some people use "TEMPER" as an all-encompassing term for heat treating... which it is not. Tempering is only one (low temperature) step within the heat treating process.

 

[Tony Park]

Sorry, I need to ask... by "tempering" you mean the process AFTER hardening, right? I take it you have something to harden your swords in already? Forge, salt pot, high temp oven?
Some people use "TEMPER" as an all-encompassing term for heat treating... which it is not. Tempering is only one (low temperature) step within the heat treating process.

yes that's correct. I have a long charcoal forge with homemade tuyere for heating up to critical temps.

This process has me thinking though that I will build another of these with higher temps for heat treat and then use this one i'm building now for temper. i can fire them both up and go from heat to quench to temper back to back.

I can save my lungs for cigars and my throat for whiskey. Nothing like a good Balvenie doublewood, or an Oban and some good bluegrass.

 

[Natlek]

Wow natlek, this is a real gift to me. Thanks so much. is there a reason the red element lines dont extend past the thermocouple?

what are the tubes made of? I suspect steel but maybe only the inner tube is steel, then insulating kaowool, then something like adobe/concrete ? or something? The outer steel pipe is probably going to be very expensive.

Do the heating elements need to be as long as the blades I treat or would shorter do? Is there a recommended size.

How much insulation thickness should i get?

Stacy has been incredibly kind to send me parts. Where is the rest of the stuff available? who is the best/least expensive to buy from?

Thank you so much for this. Nothing like a map to bring the territory closer to home.

Tony

Fan blade for kitchen oven fan is about 6 inch Dia. So inner tube must be at least one inch more wide .Heat elements can be found in different shape and length .I will use two or three heat elements like on this sketch ...they are 17 inch long , I forget how much watts they are ...I haven't bought them yet, just looked at one store what choice I have .Heat elements don t need to be long as oven .Fan will circulate air inside like on sketch and will equalize the temperature inside oven.
For inner tube , I will use stainless one with thin wall.I can find them very cheap in scrap yard .For the outside I will use aluminum tube .No need to be kaowool for insulation . Cheap rock / mineral wool is more then enough for this .
I can t help you with how much watts you need , depends on length and Dia. of your oven ......Tube don t need to be round you can use square one .......that would not make any difference .I will use round because i can easy get them and somehow it is more easy to build and install insulation .I will use two inch insulation ...Look this thread for tempering oven i already build , different construction but same principle...
https://bladeforums.com/threads/building-tempering-oven.1607678/

This is Fan for kitchen oven

 

[Stacy E. Apelt - Bladesmith]

Tony,
I will point out a few things:
1) Doing yaki-ire hardening of a katana in a coal forge may be less than optimal. A propane forge would be much easier.
2) Building a sword length HT oven is a lot more complex than making a long tempering oven. It will need a dedicated 220VAC socket rated at 20-30 amps. It won't be cheap to build.
3) Natlek's tempering oven should work, but for a sword length oven I would run the elements all the way down the top and not just in the rear. 110VAC Quartz rod heaters would probably work fine. They draw roughly an amp per 100 watts. A quick search found a 20" rod at 550 watts and costs about $50-60. I saw them at 800 watts, too.

 

[Tony Park]

Tony,
I will point out a few things:
1) Doing yaki-ire hardening of a katana in a coal forge may be less than optimal. A propane forge would be much easier.
2) Building a sword length HT oven is a lot more complex than making a long tempering oven. It will need a dedicated 220VAC socket rated at 20-30 amps. It won't be cheap to build.
3) Natlek's tempering oven should work, but for a sword length oven I would run the elements all the way down the top and not just in the rear. 110VAC Quartz rod heaters would probably work fine. They draw roughly an amp per 100 watts. A quick search found a 20" rod at 550 watts and costs about $50-60. I saw them at 800 watts, too.

Agreed on the propane. It's high time.
I was hoping i wouldn't need 220 for an HT oven. awww crap!!!!!!!
I'll get on searching for quartz rod. What about kanthal wire? will that work as well? is quartzrod more durable and long lasting? it's almost never a cost savings to build just for avoiding cost.

I too think rod that runs all the way up and down the tube makes more sense. I'm going to get some steel tubing on monday. Since this thing isn't ever going to get hotter than 600 fahrenheit, i thought making a 7 inch square tube out of mild steel sheet, surrounded by a couple inches of kaowool and enclosed in a plywood box makes the most sense. I'd like something sturdier like a 7 inch steel tube, but thats close to 400.00 for starters.

Stacy, anyone feel free to weigh in. how thick should the steel sheet be?

 

[Natlek]

Tony,
I will point out a few things:
1) Doing yaki-ire hardening of a katana in a coal forge may be less than optimal. A propane forge would be much easier.
2) Building a sword length HT oven is a lot more complex than making a long tempering oven. It will need a dedicated 220VAC socket rated at 20-30 amps. It won't be cheap to build.
3) Natlek's tempering oven should work, but for a sword length oven I would run the elements all the way down the top and not just in the rear. 110VAC Quartz rod heaters would probably work fine. They draw roughly an amp per 100 watts. A quick search found a 20" rod at 550 watts and costs about $50-60. I saw them at 800 watts, too.

Length of heat element don t matter in oven like this .Watts ! This is convection tempering oven .That mean that AIR is what give temperature to Katana not elements ......and circulating air will make heat uniformity inside oven EVEN in every INCH space inside ..........i make many test with oven like this and I have all parts , i just need time to assembly it .........
I would not use quartz tube , they heat to fast and complicated building because have power connection on both ends...so one end would be in door side .......complicated in my book .
Using elements in shape of U make building easy because two power ends would be in rear on furnace and + make it more safe .
I don t know in USA , but here you can buy very , very cheap this elements .They come in whatever length you want , even 40 inch one ......

 

[Stacy E. Apelt - Bladesmith]

A tempering oven can easily run on 115V. A HT oven the size needed will require 220V.

While I understand Natlek's intent, I feel that the fan in a closed 6" round tube 40" or longer will not evenly distribute the heat. A full length element will be better.

 

[Tony Park]

A tempering oven can easily run on 115V. A HT oven the size needed will require 220V.

While I understand Natlek's intent, I feel that the fan in a closed 6" round tube 40" or longer will not evenly distribute the heat. A full length element will be better.

Ok understood. I was planning to get a full length element. Next question. Is there a minimum thickness for a mildsteel plate? it will be much cheaper for me to get some sheet to make a square tube. Cost is a factor here. I have plenty of plywood and kaowool is cheap enough, i can encase the mild steel plate tube in kaowool and plywood.

 

[Tony Park]

Length of heat element don t matter in oven like this .Watts ! This is convection tempering oven .That mean that AIR is what give temperature to Katana not elements ......and circulating air will make heat uniformity inside oven EVEN in every INCH space inside ..........i make many test with oven like this and I have all parts , i just need time to assembly it .........
I would not use quartz tube , they heat to fast and complicated building because have power connection on both ends...so one end would be in door side .......complicated in my book .
Using elements in shape of U make building easy because two power ends would be in rear on furnace and + make it more safe .
I don t know in USA , but here you can buy very , very cheap this elements .They come in whatever length you want , even 40 inch one ......

natlek. i noticed you used long ceramic tile for the inside chamber. why? isn't metal better for this? i ask because im not sure i can get long ceramic tile in the USA. i love your design. it is genius!!!

 

[Tony Park]

Ok so... I cannot find a 36 to 50 inch heating element. Anyone want to help? I live in the usa

 

[Stacy E. Apelt - Bladesmith]

Any tube, ,round or or square, will work. It is just a shell to wrap the insulation around. Think of this project as a long thin toaster oven. Sheetmetal would be fine. Use two elements if needed to get the desired length. You could even put them on separate controllers to keep the oven evenly heated.