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Dave Stephens

New Vertical Sword HT Kiln from Evenheat

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Hi guys,

 

I'm equipping my new shop in Alaska and was looking for a kiln. I currently own an Evenheat 49.5" kiln that I really like, except for one thing. The kiln is horizontal, and the door opens on the end, so if you have a sword length blade at critical temps, when you pull it out of the kiln the leverage/weight of the blade itself causes it to bend if the blade is not kept "edge up" the entire time. It's a bit of a pain.

 

So, I gave the folks at Evenheat a call. I have to say I'm very impressed with these guys. One of their engineers, Jim, returned my call and I walked him through the problem. I told him I had attempted to set my current kiln vertically, but because it caused it to be too hot at the top, and too cool on the bottom.

 

A couple of days later he called me back with an idea to do a stacked vertical kiln of 47" that had three pyrometers and three separate heating coils. We worked through a few other details and they started building. Here are the photos Jim just sent me of the partially built kiln.

 

kiln2.jpg

 

kiln1.jpg

 

The best part, it's going to be less expensive that the horizontal kiln.

 

I plan on building a plywood platform and ramp behind the kiln in the new shop such that I can stand above the kiln to pull out the blades. If the quench tank is next to it, it should make sword HT much easier. (Incidentally, Michael Pikula's shop has a five foot deep pit that serves this same purpose. Cool idea.)

 

I'll post more photos after it's done and arrives in the new shop. Also, I'll let everyone know how it performs.

 

Hopefully if this works well it will be sold along with Evenheat's regular line kilns.

 

Cheers.

Dave

 

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Love this! When I was going to build a vertical kiln, I was going to do three heat zones myself. Wih my calculations, I think what you're going to find is the top one almost doesn't even have to turn on lol.

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Hmmmm.... AWESOME! When I was annealing the sword that I am working on prior to the grinding and such, I noticed the droopy sword problem. I didn't even think that I should hold it edge up to keep it from bending... now it seems really obvious... I hope this vertical one works out for you!

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2 questions for you:

1) If you made an induction coil long enough to fit a sword do you think it would have enough power to heat it? Assuming you have a 15 kW unit (I can't remember for sure) then I think you should be able to do that, but I don't know about the efficiency losses in such a coil.

2) Why is it that you don't do high temp salt? That seems like it would be your kind of thing.

 

Even better: Use induction to melt the salt! :ph34r:

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Jerrod,

 

I'm not sure about the induction idea. I'm woefully ignorant of how the thing works or how to adjust it. The manual that came with it was written by the Chinese manufacturer and it's only technically English.

 

Since you know what you're talking about, I assume there's a way to put a "top end" on the temperatures an induction forge brings the steel to, but I'm not sure if mine has that feature (and if it does, I don't know how to use it). My forge gets steel hot, and if you leave it in there it just melts it into liquid steel.

 

Oh, and salts scare the crap out of me. They remind me too much of having an IED in your shop. Plus, I understand they make the equipment in your shop rust very quickly.

 

If you're ever in Florida I'll have to have you over so you can figure this induction forge out for me.

Dave

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Jerrod,

 

I'm not sure about the induction idea. I'm woefully ignorant of how the thing works or how to adjust it. The manual that came with it was written by the Chinese manufacturer and it's only technically English.

 

Since you know what you're talking about, I assume there's a way to put a "top end" on the temperatures an induction forge brings the steel to, but I'm not sure if mine has that feature (and if it does, I don't know how to use it). My forge gets steel hot, and if you leave it in there it just melts it into liquid steel.

 

Oh, and salts scare the crap out of me. They remind me too much of having an IED in your shop. Plus, I understand they make the equipment in your shop rust very quickly.

 

If you're ever in Florida I'll have to have you over so you can figure this induction forge out for me.

Dave

 

I have the same fear with salt pots, I just figured you were much braver than I am! Eventually I'll get the salts for their excellent control and speed.

 

If you can adjust the kW output that is what will adjust your temperature. It will be a function of surface area to mass for a given coil in your machine. The kW are a measure of energy being put into the metal. The energy is measured as heat. The metal will give off heat, which is a function of mass, surface area, and the difference in temp between the metal and the surrounding environment. Therefore there is a given combination of everything that will get it so it puts as much energy into the metal as the metal is capable of giving off (netting a constant temperature). Unfortunately this means a bit of trial and error, but definitely possible (in theory at least). Fortunately there is another option: Do it in the dark and watch for even heating, decalescence, and recalescence as you play with the power settings! Which is totally fun too. Sadly I am completely unfamiliar with your machine for more specifics.

 

Another question: Are you going to argon purge (or other inert gas) this vertical kiln?

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Jarrod,

 

I don't have any plans to flood with argon.

 

If I remember correctly, there was a long thread on the forum in which argon purges for kilns was discussed. I seem to recall that the majority of opinions was that coating the blade with an anti-scale coating rather than argon flooding was the superior (and far easier) method to reduce/eliminate scale.

 

Dave

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This is very cool, can you give us an idea of how much this costs?

 

Geoff

 

I don't know what Evenheat will charge when they put it on their website, but I'm paying slightly under $3k for it. The horizontal one is about $700 more expensive retail.

 

But, I'm buying a prototype, so again I'm not sure what the price will be if they decide to market it.

 

Dave

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Jarrod,

 

Here's what the front of my induction forge looks like. The only thing I touch are the two square buttons to start and stop it. Can you deduce anything from the control labeling on how to control Kw, etc.?

 

Thanks for the help.

 

Dave

 

induction forge.JPG

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that is what I use, also. I put a 75lb cast iron pipe in it, to provide a nice heat sink. THat will help a good bit.

kc

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Way cool Dave! I have the same spaghetti concern with horizontal kilns, and the temperature gradient problem of vertical. Can't wait to see what this thing can do! It's great to hear that the folks over at Evenheat have the fantastic customer service that is sadly lacking these days. Kudos to them! (and to you for getting the ball rolling) :)

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One of these days I'm going to get myself a proper large kiln, I really like the looks of what they're working on for you!

 

My current digital controlled heat treating oven is home-built and very small, cant do anything longer than 9 inches overall in it =(

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As soon as I seen that all I can picture is a 47" blade with a huge 2 handed tang sticking out the top B) 60 inch sword!!!

 

It does look really nice, I've came to live with the problems of my horizontal and after a learning curve have a decent system... but hanging it at temp might actually help straighten a blade. It will be neat to see work.

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That is more or less what we use for annealing annd for temper. Stackable pottery kilns that we added a digital controller to.

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I have the Paragon sword length kilns designed for horizontal use, but turned on end. It works even if it was not how they were designed to work. I have two: one used to austenitize and the other for tempering. These days I have salt tubes inserted in the kilns but I started out atmospheric. To get around the problem of heat escaping when the door was opened, I welded a plate on the top end of a tube that hung inside the kiln. I isolated this with ceramic wool to minimise heat escaping from the kiln. In the plate I cut a slit where the sword could be inserted (fixed with a locking welders clamp around the protruding tang). It would have been an easy matter to inject argon into this tube, but I never went to that trouble. A wad of paper that slowly burned took care of most of available oxygen and also produced a lovely smell of scorching paper through out the heat treating process... You can also coat the blade with anti scale compound. I have experimented with this and found that it helps even if it does not completely eliminate decarburisation.

I prefer my present set up with salt tubes. It is like playing with a volcano, but I do not see that you would not be way safer with this than I can ever hope to be Dave. I have sen your workshop. You have not yet seen mine... Be prepared for the shock of your life!
Salts give you a power of control you can never have with an atmospheric kiln. The second best is the big horizontal from kiln, to my mind. It allows you to inspect the process to transformation in a way that you otherwise can only do in a char coal forge. I like that and built myself a drum forge a few years back. I use this whenever I need to work with selective hardening or other arcane methods (which is very seldom).

This stackable kiln looks really impressive and much more reliable and serviceable than my old Paragon kilns. I would love to have two of those! The Paragon kilns do run at different temperatures at top and bottom. The salt tend to even this out, but I am not perfectly happy. (Do I have the ability to ever be perfectly happy? Probably never as sword smith...)

-So in short, I would recommend you make an inner tube with a bottom and a top lid that acts to even out the heat even further. Inside this chamber you can then easily inject an inert gas. This would really help I think.
With only an atmospheric radiant heat your time to temperature will be a long wait compared to that of a salt bath. But you can always make another cup of coffee while you wait. Decarb will be your enemy as will uneven heat to some extent.

Salt would take care of all that, but at the thrilling risk of you "loosing face" at a moments break of attention or absentmindedness. The kiln you are going to have will allow you a lot of various set ups.
I am really interested to hear about your experience with it. -Perhaps my next big investment?

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Jarrod,

 

Here's what the front of my induction forge looks like. The only thing I touch are the two square buttons to start and stop it. Can you deduce anything from the control labeling on how to control Kw, etc.?

 

Thanks for the help.

 

Dave

 

 

This is just a guess (even if a fairly educated one):

 

You seem to have 3 timers: heat hold, and cool. They appear to be set for seconds and if you leave the "Start" button on and the toggle to "auto" it should continuously cycle through the three of them. Kind of like how electric ovens work, continuously turning on and off, even just to hold temperature. The difference is that while they are either "full on" or "full off", you have the option to adjust what kind of power level you are using ("50% power on" is an option for you). On top of that it looks like you have the 2 settings to have control over (Heat and Retain). If I had to guess I would think the "period convert" button just lets you cycle to the next timer (heat, retain, or cool) before the active timer reaches zero.

 

Here is how I see that working: You know your piece is going to go in cold, and running at full power it gets to temp in about 30 seconds. But this is a crucial forge weld, so you want to make SURE that the center is up to temp, so you want it to hold a little while. To do this you would set your heat timer to 30, and heat current to max, then your retain timer to (let's say) 30 seconds and the retain current to 50%. And if you knew you were going to forge it for about 45 seconds then re-heat you could set your "cool" timer for that and just return your part to the forge. Since your part wouldn't be cold anymore you would then just want to change your "heat current" to about 75% or something, maybe adjust the time too. Those current dials are what is driving your kW, so dumping in less current is dumping in less heat. Of course you will want to be playing with all the power levels as well as times.

 

Again, that is just my take with a few assumptions. If you want to send me your induction unit I would be happy to play with it for you, but I am 100% sure it would get lost in the mail when I ship it back. And by coincidence I would receive a new one myself at about the same time. :ph34r:

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-So in short, I would recommend you make an inner tube with a bottom and a top lid that acts to even out the heat even further. Inside this chamber you can then easily inject an inert gas. This would really help I think.

With only an atmospheric radiant heat your time to temperature will be a long wait compared to that of a salt bath. But you can always make another cup of coffee while you wait. Decarb will be your enemy as will uneven heat to some extent.

Salt would take care of all that, but at the thrilling risk of you "loosing face" at a moments break of attention or absentmindedness. The kiln you are going to have will allow you a lot of various set ups.

 

I like this. Pipe within a kiln. Maybe drop a chunk of charcoal in the bottom of the pipe before adding your blade.

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Hey Peter that is a very interesting, do you think we might be able to see a photo of your setup? I have a Paragon sword kiln up at school and would love to use it vertically instead of horizontally as the warping I'm getting before the quench is annoying though not impossible to fix later.

 

Dave, this is a fantastic project! I'm excited to see what your results are!

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What kind of supports inside your horizontal kilns is allowing your blades to sag?

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I have the same oven as you Dave and I have that same problem with my blades bending. It's nerve racking every time I'm pulling a blade out. I've searched the internet for a vertical oven with no luck. After seeing this I am 100% going to get one made. This will free up some floor space in my shop. Thanks for sharing this!

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Hey Peter that is a very interesting, do you think we might be able to see a photo of your setup? I have a Paragon sword kiln up at school and would love to use it vertically instead of horizontally as the warping I'm getting before the quench is annoying though not impossible to fix later.

 

Dave, this is a fantastic project! I'm excited to see what your results are!

I can absolutely post a photo, but it will take a while before I get an opportunity.

I am in the last painful push to meet deadlines for the exhibition at the Deutsches Klingenmuseum (The Sword - Form and Thought). This is why I have been pretty much inactive this past half year or more. Not much time for anything else these days.

 

But a photo of the kilns I can manage, I am sure.

:-)

It is simple and messy but with some details that you might find useful. The main thing to keep in mmd is to make the tube *absolutely* tight. And not allow *any* salt, or residues of salt enter the kiln. It wreaks havoc with the heat elements. This is important.

Just an atmospheric tube is less fuzzy, but is very similar to the salt set up.

 

I guess I can make a sketch. It will show the important aspects more clearly than a photo will.

I can then also avoid shaming myself by showing my messy workshop :-)

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Does an atmospheric tube in a vertical electric kiln need to be thin-walled or just plain ole' junkyard sewer pipe?

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The thicker the better, it evens out the heat.

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Nice. :) I think a pipe with charcoal would do a nice job of it.

 

I'm still happy with the salts and propane- not sure I'd go with salts and electric elements.

 

Looking forward to seeing the shop complete!

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