DIY sword tempering oven

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Ok so which 2 elements on mcmaster carr should i order?`You seem dead set against using a single element; I'm going to defer to experience here can you find the 2 elements you think would work best with the stuff you are sending?

Based on the feedback from the oven forum, they made it sound like these elements should be positioned like long staples with short legs through the tube wall into junction boxes.
 
You can use a single element or two. It is your oven build. I was pointing out the concern for temperature variation and simplicity of construction.
Have you considered the element droop on a 60" single element? I have no idea if that would be an issu, buy it should be considered. You would certainly need a bigger tube.

I don't want to mislead anyone to thinking that building a 60" long tempering oven is a simple thing. It will take understanding HT oven building and controllers, as well as suitable construction skills. It will have some amount of cost, even if you keep the materials as low as possible.
If I was to make a guess, I would suspect that about 1% or 2% of the folks on this forum could do one and get a good result.
 
Stacy E. Apelt - Bladesmith said:
You can use a single element or two. It is your oven build. I was pointing out the concern for temperature variation and simplicity of construction.
Have you considered the element droop on a 60" single element? I have no idea if that would be an issu, buy it should be considered. You would certainly need a bigger tube.

I don't want to mislead anyone to thinking that building a 60" long tempering oven is a simple thing. It will take understanding HT oven building and controllers, as well as suitable construction skills. It will have some amount of cost, even if you keep the materials as low as possible.
If I was to make a guess, I would suspect that about 1% or 2% of the folks on this forum could do one and get a good result.
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Ok so, the whole purpose of this is to MAKE it a simple thing anyone, even an idiot like me can do. As a former financial process engineer at Intel one thing I've grown to hate is touching something twice. I dont want the next guy to have to go thru inventing the wheel.

I estimated earlier that I would need an 8 inch tube at minimum, sot thats the only thing I've purchased. Beyond that, I need to know if the 60 inch element, which will be closer to 50 inches after the ends are bent thru the insulation and tube wall to junction boxes.... I need to know if you have controllers and such for an element that size and power.

If so, then lets do this. The oven folks at the oven forum seem to think that it will get plenty hot as a vertical oven for swords.

Natlek is under the impression I think that the terminus of the elements is at the ends of the tube. They are not. Think of it like a long staple with short legs coming out the side of the tube.
 
Tony Park said:
Ok so, the whole purpose of this is to MAKE it a simple thing anyone, even an idiot like me can do. As a former financial process engineer at Intel one thing I've grown to hate is touching something twice. I dont want the next guy to have to go thru inventing the wheel.

I estimated earlier that I would need an 8 inch tube at minimum, sot thats the only thing I've purchased. Beyond that, I need to know if the 60 inch element, which will be closer to 50 inches after the ends are bent thru the insulation and tube wall to junction boxes.... I need to know if you have controllers and such for an element that size and power.

If so, then lets do this. The oven folks at the oven forum seem to think that it will get plenty hot as a vertical oven for swords.

Natlek is under the impression I think that the terminus of the elements is at the ends of the tube. They are not. Think of it like a long staple with short legs coming out the side of the tube.
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If it is mine build I would use two element like this ..........https://www.mcmaster.com/3540K43/
I don t understand why you would bend them so ends/legs to come out in side of tube ? Why not in rear end of tube ? That way you get legs of element out of higher temperatures .Remember high temperature wire can handle max. 250 Celsius and you will use that oven in much higher temperature for tempering swords . So it is better if legs come out on rear wall and probably you will need to use at least 5 inch bare cooper wire with ceramic beads to be on safe side ..............look this thread , it is heat treat oven not tempering oven but I think that will help you to see what you need to do .
One more thing , don t forget to support elements on several place inside tube .
https://bladeforums.com/threads/tube-furnace.1632557/
 
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Natlek said:
If it is mine build I would use two element like this ..........https://www.mcmaster.com/3540K43/
I don t understand why you would bend them so ends/legs to come out in side of tube ? Why not in rear end of tube ? That way you get legs of element out of higher temperature .Remember high temperature wire can handle max. 250 Celsius and you will use that oven in much higher temperature for tempering swords . So it is better if legs come out on rear wall and probably you will need to use at least 5 inch bare cooper wire with ceramic beads to be on safe side ..............look this thread , it is heat treat oven not tempering oven but I think that will help you to see what you need to do .
One more thing , don t forget to support elements on several place inside tube .
https://bladeforums.com/threads/tube-furnace.1632557/
Click to expand...

The reason I want to use one element is simple.

If i did as you suggest. how would I get even temps? The longest element they sell is 60 inches. bent in half would be roughly 30 inches. So i can mount one at the bottom of the vertical tube.

Where does the top one covering the remainder come out of? Its a vertical oven. The top should be a door. Doors move. cant have a element terminating thru a door.

So why not have ONE element? One element terminating along the side wall of the tube with heat proof wiring? Think of it as a long staple. LOOOOOOONG staple.

The other benefit of this is that I dont need a fan. I cant imagine making anything longer than 48 inches. If an 8 inch tube with 2 inches of kaowool can't hold 500 degrees evenly.. in a 6 inch by 50 inch space-ish...then this simply cannot be done.

At most, i anticipate having to turn the blade every half hour to have both blades have some time to face the element down its length.

Does this make sense?
 
I m sorry , i was thinking that elements are 65" long as they are shown in the picture there .I thought that it is 2 x 65 inch as it is bend or 130 inch straight element.........
 
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Tony Park said:
Where does the top one covering the remainder come out of? Its a vertical oven. The top should be a door. Doors move. cant have a element terminating thru a door.

So why not have ONE element? One element terminating along the side wall of the tube with heat proof wiring? Think of it as a long staple. LOOOOOOONG staple.

The other benefit of this is that I dont need a fan. I cant imagine making anything longer than 48 inches. If an 8 inch tube with 2 inches of kaowool can't hold 500 degrees evenly.. in a 6 inch by 50 inch space-ish...then this simply cannot be done.
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You can mount them on side walls ...like on picture . You can use some ceramic for insulation for steel tube .
I m sorry but in vertical oven long as this one you will have lot of difference in temperature top to bottom without fan .Fan is only thing that can make this oven to work .............and I m Million % sure in that .
ggh89dq.png
 
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I think two 36" elements should work once the ends are bent.
Make sure you get the right type, as there are bend-and-stay elements for liquids only and others for ducts.
https://www.mcmaster.com/heat-eleme...nd-stay-heaters-for-ducts-ovens-and-dryers-7/

You should use two elements, each with its own controller. Read my suggestion below.
One thing you need to consider is making sure the sword does not contact the elements. Not a huge problem, but something to consider.
Also, you need some ceramic pass-through tubes for the elements to pass through the tube wall.

I know you want us to tell you - "Buy this and that and that", but you are the one building it. You need to understand which parts will work and how to install them.
You should draw it up your oven plan completely. Have multiple aspect drawings and a detailed list of every item you need. Putting a link by each item will allow others to make sure you have picked the right parts.

As an idea that may make the build much simpler and really good looking is getting two sections of tri-wall chimney and making each as an independent tempering oven. It will make installing the elements much easier, too. That way you can join or separate them with a twist and have one long or two shorter tempering ovens for regular knives. Merely set both controllers for the same temp when joined. This will take out the need for any outer insulation, and you will only need sheets of 1/4"thick by 14" wide insulation to line the chamber with. You can actually use no insulation at all inside the chamber if you have the element installed and use a couple ceramic standoffs to hold them in place. This is how I plan on doing mine.

The chimney comes in 24" and 36" sections, so you could use one of each to get a 60" tempering oven, and separate them to have a 24" and a 36".
1" ins-board would be perfect for the tops and bottoms. HTT&R sells the insboard at a good price.
Here is what I am talking about:
https://www.amazon.com/Duravent-Gal...himney+pipe&qid=1613763289&sr=8-4&tag=mh0b-20
 
It's not so much that I want you to tell me what to buy, although that would make this exercise infinitely easier.

It's mostly because I don't know what controllers you have and so some of this is beholden to what you have.

Can you tell me why 2 controllers and two elements will be better?

Is one element likely not to be consistently hot along its length?

It seems like a needless complication, but I'm perfectly willing to concede there's something I could be missing.

The ceramic pass thru is a good idea of course. I'll add that to the list.

Having 2 separate kilns that one can put together seems ok on its face, but since this is a vertical oven so that gravity doesn't warp the blade it seems to make more sense to keep it as one unit.

Do you have a controller etc to support the element I wanted to use?
 
Natlek said:
You can mount them on side walls ...like on picture . You can use some ceramic for insulation for steel tube .
I m sorry but in vertical oven long as this one you will have lot of difference in temperature top to bottom without fan .Fan is only thing that can make this oven to work .............and I m Million % sure in that .
ggh89dq.png
Click to expand...

Natlek said:
You can mount them on side walls ...like on picture . You can use some ceramic for insulation for steel tube .
I m sorry but in vertical oven long as this one you will have lot of difference in temperature top to bottom without fan .Fan is only thing that can make this oven to work .............and I m Million % sure in that .
ggh89dq.png
Click to expand...
If the element runs down the whole length of the tube... how is it possible there will be significant temperature variation?

Unless the element is not consistently putting out heat....you have to provide an explanation for this.

What you are saying makes absolutely no sense to me. Please tell me why you are right?
 
Tony Park said:
If the element runs down the whole length of the tube... how is it possible there will be significant temperature variation?

Unless the element is not consistently putting out heat....you have to provide an explanation for this.

What you are saying makes absolutely no sense to me. Please tell me why you are right?
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Tony , the hot air will rise that is problem .Even in an ordinary small tempering oven say like one they build from toaster oven you have heat zones with different temperature ..........door to back and top to bottom .
Elements inside are JUST source for energy , they can t make even temperature inside no matter how long they are . Thermocouple will help , but it measure temperature in only one spot .Where you plan to mount it ? In middle ? Wherever it is, it will show the exact temperature only in that spot .This is long oven , to much long to control temperature only with thermocouple .If I turn fan off in mu tempering oven it will lose uniform temperature. I made lot of test and read thousands of pages around this issue .Ask your self why all professional tempering furnaces have fan , every single one of them ?
 
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Natlek said:
Tony , the hot air will rise that is problem .Even in an ordinary small tempering oven say like one they build from toaster oven you have heat zones with different temperature ..........door to back and top to bottom .
Elements inside are JUST source for energy , they can t make even temperature inside no matter how long they are . Thermocouple will help , but it measure temperature in only one spot .Where you plan to mount it ? In middle ? Wherever it is, it will show the exact temperature only in that spot .This is long oven , to much long to control temperature only with thermocouple .If I turn fan off in mu tempering oven it will lose uniform temperature. I made lot of test and read thousands of pages around this issue .Ask your self why all professional tempering furnaces have fan , every single one of them ?
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Stacy needs to answer this first part.

1) is there significant deformity of steel in tempering ovens, as opposed to heat treating ovens due to gravity? I kind of doubt it.

2) If heat rises and the heat difference is significant....is it going to be 10% or MORE? Relatedly will that make a difference in how the sword tempers such that the quality of the final product is tainted?

Natlek. If the answer to my question 2 is Yes and YES. Then the answer seems very readily apparent. I will make my tempering oven horizontal. There will not be enough temperature variation across a 6 inch space, as long as the element runs down the length and is on the "bottom" of the now horizontal pipe. All else should be quite similar to your diagram.

By the by, you make a leap of logic that is a little dangerous when it comes to design. Yes, there is a reason fans come included with most ovens, It's because they are cubes. Mostly. when heat treating in a cube, convection becomes an issue. because small knives and usually a few of them in an oven. heat rises as you say. if you want 10 knives heat treated at the same time in the same oven you will want them placed throught the oven.

But in a horizontal tube, the maximum it can rise is 6 inches. I'm willing to bet a fair bit heat mechanics are far more efficient in a round tube.

Also, never thnk that beacuse everyone else does something that there must be a reason. Groupthink is a terrible thing. Especially in engineering. or, in my case, redneck backyard construction.

Nasa spent millions designing a pen whose ink would flow in space. The Soviets just used pencils.
 
Tony Park said:
Also, never thnk that beacuse everyone else does something that there must be a reason. Groupthink is a terrible thing.
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Conversely just because you think it's a good idea doesn't mean that it is.

You came along for advise, people gave you advise. Lots of these folks have years and years of experience making their own gear. Why not use their experience to your benefit and follow their recommendations?

By all means though, go out and make whatcha wanna make and see how it works out? You've got lots of parts lists and references... Now go make something!
 
A.McPherson said:
Conversely just because you think it's a good idea doesn't mean that it is.

You came along for advise, people gave you advise. Lots of these folks have years and years of experience making their own gear. Why not use their experience to your benefit and follow their recommendations?

By all means though, go out and make whatcha wanna make and see how it works out? You've got lots of parts lists and references... Now go make something!
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I've b0eep
 
As you get to know me, you might realize that I'm actually right more often than not once I make a decision about something.

I'm no stranger to building things, just different things.

When natlek says "every oven maker"...this usually is a horrible logical fallacy. I know he means well, but this is incorrect thinking. I understand well enough why natlek is incorrect. If I were making small blades, a cube style oven may be just the thing. But I make large blades.

I'm waiting for Stacy to respond to some questions I had above. I take advice if I understand it and its complete. Then I can start building something.
 
1) is there significant deformity of steel in tempering ovens, as opposed to heat treating ovens due to gravity? I kind of doubt it.Tony,
This question makes me feel you don't know enough about what you want to do. It is martensitic at temper, which is rigid. It is austenitic at HT temps, which is soft and sort of rubbery ( relatively).

Your second question and some of your assumptions have to do with thermodynamics and oven design/engineering. This is a very complicated field.

As to your statement about why things are done in industry, it has nothing to do with group think. It has to do with engineering, science, and design. Those guys spend years learning what they do. If all it took was a fellow saying, "Hey, let's do it different" to make it so, there would be no need for Beta testing.

I would recommend you considering Occam's razor on such things.

As to the controllers, as I said to you earlier, once you design the oven and settle on what elements you will use, I can send you the correct controllers.
 
Stacy E. Apelt - Bladesmith said:
1) is there significant deformity of steel in tempering ovens, as opposed to heat treating ovens due to gravity? I kind of doubt it.Tony,
This question makes me feel you don't know enough about what you want to do. It is martensitic at temper, which is rigid. It is austenitic at HT temps, which is soft and sort of rubbery ( relatively).

Your second question and some of your assumptions have to do with thermodynamics and oven design/engineering. This is a very complicated field.

As to your statement about why things are done in industry, it has nothing to do with group think. It has to do with engineering, science, and design. Those guys spend years learning what they do. If all it took was a fellow saying, "Hey, let's do it different" to make it so, there would be no need for Beta testing.

I would recommend you considering Occam's razor on such things.

As to the controllers, as I said to you earlier, once you design the oven and settle on what elements you will use, I can send you the correct controllers.
Click to expand...
 
Tony Park said:
Natlek. If the answer to my question 2 is Yes and YES. Then the answer seems very readily apparent. I will make my tempering oven horizontal. There will not be enough temperature variation across a 6 inch space, as long as the element runs down the length and is on the "bottom" of the now horizontal pipe. All else should be quite similar to your diagram.

Nasa spent millions designing a pen whose ink would flow in space. The Soviets just used pencils.
Click to expand...

Well , if you use it in horizontal position ,maybe you will make something usable .....
I always wonder if that story with million dollar pen is true ?
 
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