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David D.

New Sword Heat-Treating Kiln - Advice from fellow Kiln-ers?

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Hey everyone,

I just wanted to share my new acquisition in my workshop... A tool that I'm now the proud and thankful owner of. A beautifully built, custom made, electric heat treating kiln for my sword blades.

Checkout some photos:

image.jpg

 

image.jpg


I am really really pleased with it.
Its undoubtedly going to make my life a LOT easier and less stressful when it comes to heat treating.

 


I need to give a BIG thank you to Michael Lenaghan, who kindly gave me all of the details of how he custom ordered his own identical kiln! Which mine is based off of. Seen here:
http://www.bladesmithsforum.com/index.php?showtopic=23692&hl

(Michael and I are technically the only two guys in the world who own such a strange Frankensteined sword-in-mind made kiln) :)

Michael kindly pointed me to the local ceramics company who he bought it from, the Sounding Stone, in Canada:
http://soundingstone.com/splash.do
I contacted them, and they then had a kiln making company called "Olympic Kilns" custom build it for me.
Their site: http://www.greatkilns.com/

It was much more affordable than some of the other kilns on the market, and I like this design much better because its a top loader instead of a side loader.
Yes the heat escapes dangerously when you open it up at critical heat, but its a danger worth risking right!?... ;)


Ironically, I also fixed my old propane sword heat-treating forge, which I asked for advice about on here, and you guys kindly chimed in.
here is what it looks like currently:

image.jpg

 

 

I have no regrets about buying my kiln, even though my propane is working great too.
I plan on using them both in tandem, for different purposes and in different ways.


 


A couple questions for those of you with experience or knowledge with putting pointy pieces of steel into a kiln like this.....

1: What would be my wisest option of placing a blade in the kiln? Obviously I think laying a double edged sword flat on the floor would make the top side hotter than the bottom, so that's a no no.
But what if I laid a sword blade on a few little chunks of broken fire brick, evenly spaced and all the same height, so that they raised the blade enough off the floor that both sides might evenly heat??
Or should I lay it in on one of the two edges? the blade being perpendicular to the floor? If so, how??

2: I've forever heard/read here on the forum about some of you guys using "Anti-Scale" stuff on your blades prior to heat treating. I feel that with a setup like this I should now consider it??
With that in mind; what the hell even is "Anti-Scale" for steel??? And where can I find it? Or can I make it???
I'm sure google could answer this question for me. But I trust you guys more.. :)

 

 

 

Please let me know your thoughts, ideas, distractions, or your opinions on the Geo-political nature of lama's in the comments below!... ;)

Thanks guys

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ok - I have a vertical evenheat that I got through Tim Zowada. I put a huge cast-iron pipe in mine for a retort. The great thing is that it really, well, evens the heat. The bad thing is that my thermocouple measures the outside of the pipe and my blades sit inside.

 

Still, if you have issues with holding tight to a temperature, put a huge piece of metal inside it, permanently. Maybe a big "u" channel.

 

Put the blade in, on a rack like knife makers do, only put it spine down and edge up when it is single edges. place a stainless steel rack that holds the blades so they are perpendicular to the floor. This should cause them to get max and even radiant heat from the elements.

 

don't lean over the thing when you open it!

 

having a controlled kiln is WONDERFUL for confidence and quality control. plus, it has let me expand into o1, 80crv2, and I may add 52100 some day (but 80crv2 is soooooo cooool, I may not).

 

It will also help you get the absolute most from W2 and 1095.

 

great score!

kc

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Nice!

 

Anti-scale is available from Brownells or Blacksmiths Depot, and is well worth it. You can kinda sorta get by with a very thin coat of clay, but the real stuff is infinitely better.

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Thanks so much Kevin and Alan! :) I really appreciate the insight and advice

 

I will definitely be buying some anti-scale from one of those sources for sure.

I'm going to need to do some experimenting with my placement of blades inside of this thing for sure...
I'm doing mostly doubly edged sword, not single, so I need to take that into consideration.

I hadnt thought about a long tube of metal Kevin? Great idea.

Thanks!

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http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/heat-treating-accessories/anti-scale-coating-prod23076.aspx

 

ATP-641. I use it every time, and it's great and it doesn't get in the way of quenching.

I have problems with even heating in my 'evenheat' kiln. I guess these are heating partly by convection, partly by radiation. If I put two or more blades in there for normalizing, they will end up bent towards each other. I have to place one blade per cycle in the middle of the furnace. So even heating can be had by blocking the IR, but the temp probe is no going to tell you the whole story. Hanging the pieces vertically seems to help, and with a coffin lid like yours, might be the way to go. That will prevent it bending under its own weight, but not the uneven heating problem. I've seen some more expensive, sophisticated convection ovens where the items to be heated are blocked from IR radiation from the coils by conventional ceramic refractory bricks. The indirect heat from the coils is circulated by a fan in the oven, so all heating is by convection, not radiation. This makes for a more even heat if the air passages are properly done. If you have a deep c-channel, or a pair of angle irons, or a square tube with the top cut off... those will probably help with getting more convection and less IR.

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Oh by the way, that kiln kicks ass! I like the coffin lid door, and the way the wool seals around the bricks.

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Thanks for the advice Brian! :) Good insight and thoughts to chew on there. I appreciate it.

It looks like the type of Anti-Scale you guys have all refered too is out of stock on that website??:
http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/heat-treating-accessories/anti-scale-coating-prod23076.aspx

this stuff however is listed as an alternative:
http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/heat-treating-accessories/non-scaling-compound-sku083015100-1122-4011.aspx
Would this stuff do the trick?? Or is it not what I should go with??

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That looks like a great kiln, I'm excited for you! Out of curiosity, is it running 220? I can't imagine it working well on 120, but you know what they say about inquiring minds... :rolleyes:

 

I've tried satanite as an anti scale compound and it works fairly well (nothing to compare it to though). It comes as a dry, very fine powder that can be mixed well for thin coats. I have heard that scale is less of a problem in electric ovens because of the relatively stagnant atmosphere and lack of radicals introduced, but then there will always be some degree of scale wherever you work, unless it is a vacuum! (wouldn't that be neat!) I wouldn't recommend placing anything flat (held off the ground on bits of brick or something) for buckling reasons, however short.. Unless you had a sort of 'bed of nails' sort of thing that allowed for natural convection underneath. Even that might lead to problems though, depending on the layout. Then again, I have never used an electric kiln before, so that could all be completely irrelevant.

 

John

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Nice addition, David!

 

Just to add a bit to what others have said: I would get a couple of ceramic blade stands like these:http://www.knifemaking.com/product-p/kf632.htm

 

This will allow you to place the sword edge down/up rather than flat in the kiln. The main reason for this is to keep the sword from bending under it's own weight as you take it from the kiln at critical heat. As you know, this is one of the main reasons a lot of smiths use vertical heat treat devices to heat their blades.

 

I love my sword kiln, but I think the top opening feature of yours would make it even better. I'm always very on edge (no pun intended) as I carefully extract the blade from the end of the kiln. Lifting it directly out of the kiln from the top would be much better, I think.

 

Final thought (and apologies if you already know this): The biggest "doh!" moment of my kiln experience came from not understanding how much heat the fire bricks retain. I once heated a blade to critical, quenched it, then allowed the kiln to cool for a few hours until the thermocouple read the correct tempering temperature (with the doors open) . .. then placed the hardened blade back into the kiln, set the temperature to the tempering range and left the shop. An hour or so later I came out to find the temp at over 1000 degrees F, obviously ruining the hardening of the blade. Bottom line: Let the kiln cool until you can touch it without blistering before you use it to temper.

 

Cheers brother!

 

Dave

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I second the anti scale, but remember it is anti scale not anti decarb... I have had recent issues with spots of deep decarb in pattern weld when hardening in the kiln and using anti scale ..

Nice Kiln!

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Another anti-scale option: If your kiln is fairly well sealed you could pipe in an inert gas (argon, CO2, and blends there-of are easy to get at a welding supply store, dry ice is a good source too). If you can fill the chamber with the gas it will displace the oxygen and therefore no scale. You would have to be able to pipe it in with the lid slightly ajar then close it up. Won't be perfect but it could/should help. It'll help your heating elements last longer too. Only works if the kiln is fairly air tight, otherwise you have to keep piping gas in. That gets a little spendy and complicated.

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Thanks guys! Really great insights here. I appreciate it.

That looks like a great kiln, I'm excited for you! Out of curiosity, is it running 220? I can't imagine it working well on 120, but you know what they say about inquiring minds... :rolleyes:

 

Hey John! Yep its 220 ;) Andy was home visiting family and kindly helped me wire it all up.

Nice addition, David!

 

Just to add a bit to what others have said: I would get a couple of ceramic blade stands like these:http://www.knifemaking.com/product-p/kf632.htm

 

This will allow you to place the sword edge down/up rather than flat in the kiln. The main reason for this is to keep the sword from bending under it's own weight as you take it from the kiln at critical heat. As you know, this is one of the main reasons a lot of smiths use vertical heat treat devices to heat their blades.

 

I love my sword kiln, but I think the top opening feature of yours would make it even better. I'm always very on edge (no pun intended) as I carefully extract the blade from the end of the kiln. Lifting it directly out of the kiln from the top would be much better, I think.

 

Final thought (and apologies if you already know this): The biggest "doh!" moment of my kiln experience came from not understanding how much heat the fire bricks retain. I once heated a blade to critical, quenched it, then allowed the kiln to cool for a few hours until the thermocouple read the correct tempering temperature (with the doors open) . .. then placed the hardened blade back into the kiln, set the temperature to the tempering range and left the shop. An hour or so later I came out to find the temp at over 1000 degrees F, obviously ruining the hardening of the blade. Bottom line: Let the kiln cool until you can touch it without blistering before you use it to temper.

 

Cheers brother!

 

Dave



Thanks Dave! This is awesome

I appreciatre the link for the kiln-blade stands.
Though I will admit; I'm a bit confused by those? How many would I need? Especially for a long blade?
I tried making my own up out of some mig welded steel rods, and it sorta worked, however with two holding the blade up on either end, if its barely leaning to one side then the blade seems to lean under its own weight even then.
Even when it was on edge, it still warped to one side in a test with a scrap blade.
However I could have maybe just placed the stands too far apart? or m stee not normalized nicely, or too close to one of the walls, making it hotter on one side.

 

As for the kiln brick-heat advice: Thank you! :) I do rememeber you mentioning that too me.
I will definitely keep that in consideration.

 

i certainly think this thing will pay off the most when it comes to tempering, even more than hardening. My propane forge never did a bad job of getting it evenly heated for hardening, it was whe it came to tempering that I always struggled.


Thanks guys!

if anyone else has any other ideas about how to most-wisely place m sword blades instide to avoid warping then I'd really appreciate it!

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Dave, love your work and that new kiln is awesome.

 

The blade holders linked to above will always allow the blade to tilt to one side or the other unless the upright posts have a gap between them that's the same thickness as the blade itself. You'd have to have something that's adjustable to keep the blade from flopping to the side.

 

I have two ideas that will solve that problem, but I'm not conversant with swords and how bendy they are at temperature.

 

Idea 1: Wine-bottle holder.

wine-bottle-holder.jpg

It would hold tang of the sword in an edge-up orientation, the edges of the hole biting into the tang and allowing for different sizes. It would be very easy to slip onto the tang and put the entire thing into the forge. Also easy to remove on the way to the quench tank.

 

It doesn't have to be a counterweight/cantilever design like this. I just used that because it's a neat visual.

 

Idea 2: Feather and Wedge

 

A little something from my stone working days, thankfully a very short experience!

fig04.jpg

 

If you imagine that the wedge (middle piece) is the tang of the sword, the feathers (side pieces) slip between it and the uprights on a ceramic rest like has already been mentioned. This stops the blade from flopping over, minimizing any twists.

 

Again, very easy to make in the shop and would adjust for variation in the tang thickness.

 

If you need to support the tip of the sword against side flop, that complicates things.

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I'm using argon in my kiln currently, but I just got it set-up so I haven't had too much time to get a feel for it. It does reduce scale to almost nothing, and I'm finding it takes only a very small amount. So far just a quick blast at the beginning seems to do the job fairly well. I'm thinking the 40lb tank I got will last me about 20 years...

I'll post a full report with pics in another 6 months or so, once I figure it out how best to use it.

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I'm using argon in my kiln currently, but I just got it set-up so I haven't had too much time to get a feel for it. It does reduce scale to almost nothing, and I'm finding it takes only a very small amount. So far just a quick blast at the beginning seems to do the job fairly well. I'm thinking the 40lb tank I got will last me about 20 years...

I'll post a full report with pics in another 6 months or so, once I figure it out how best to use it.

 

I'd love to learn more about your experience w/ Argon in this capacity. I've toyed with the idea of building a heat resistant glass enclosure around my induction coils and filling it w/ Argon so I can do billet welds in my induction forge.

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yeah I would like to hear more on that to, my set up is stackable nice as I can adjust the size , but it is very leaky, I am contemplating building another with argon purge for kitchen knives to avoid the decarb issues I have been having.

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That propane set-up is one stainless pipe away from a nice salt-tank rig. The kiln would remain entirely useful for tempering and you wouldn't have to worry about scale. I'd be happy to chat more if you're interested or have any questions about the idea.

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Thanks for all the more thoughts and insights guys!

 

VaughnT,
those are some very clever ideas. :) Unfortunately I do think the wine
bottle method would result in long sword blades warping under their own
weight at that heat. Though it would work perfectly for smaller pieces!?

That propane set-up is one stainless pipe away from a nice salt-tank rig. The kiln would remain entirely useful for tempering and you wouldn't have to worry about scale. I'd be happy to chat more if you're interested or have any questions about the idea.

 

Man you are officially now tempting me to go down that path... ;)
haha

You may be revieving a message then in the next few days. :)
I really appreciate it!

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Do it once you go salt you will Never want to do anything else... even with the issues and danger of salt it is by far the best method for hardening!

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Dave, is there any reason why you couldn't stand the oven on end?

 

Looking at the design, I don't see any reason why you couldn't put it up on a cinder block, screwing one leg to a wall stud, and open it like a fridge. Then it would only be a matter of putting in a hanger unit so the blades could dangle in the warm air.

 

Yea, the DRO would be sideways, but that's small potatoes.

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You can't stand these type of kilns on their end. It screws up the temperature regulation. The thermocoupler is in the middle, and they are so long that the heat rising to the top of a kiln tipped on it's end totally screws up the precision of the temp control.

 

Of course, I figured this out purely from logic. I never would have tried this myself and totally have screwed up a couple of heat treats before I figured it out. Nope. Never happened. My story . . .I'm sticking to it.

 

Grins,

 

Dave

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An excellent use of logical deduction, Dave. :D

 

I'm all out of ideas so I'm going back to my corner.

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-bit of advice

i wouldn't lay anything on the floor.. the surface of the brick tend to be a tad cooler, and if you lay the long sword on that ... you'll notice it'll warp that way when quenched

-if you suspend, make sure there is adequate support or it may sag... depending on how you did it .. even some 1/4 " round rod spaced out will help to get off the bricks

- you can suspend with stainless wire or.. stainless round rod ( just make sure the height is even ) and becareful not to touch those heating elements, they are a live wire ( BzzzZZzzzzzzzzzTTT )

- if you are on the cheep ...like i am... just get a piece of iron flat bar... weld a bunch of nail sticking up... and use those as slots to hold you blade up vertical... who cares if the iron scales away in 2 years... its cheeper than buying a 14 buck alumina knife holder that the kiln guys will sell you..

 

Pick: how to pick

- a single tong pick is hard to do ... so use two tongs... ! on a horizontal/ side door, it is easy ... a short box tong for the tang and a flat tong or 1/2 round bar for the middle support .... basically the box tong is in your left hand, clamp it on the tang and pull sword out, BUT you are using the other tong with your right hand to support the middle of the blade as you slide it out ...... once out of the kiln you simply raise your left hand, and lower your right at the same time and it will point the tip of the sword down and .... quench it ( its one fluid motion and if you do it right and evenly ... it'll be straight )

 

for your set up.... you'll need a special angled box tong for the tang.... and i'd use a sort of cane like bar for support in the middle .... same idea, just different motion ............. slip the crook of the cane under the middle of the blade... and box tong for the tang.... and lift

 

becareful of the live wires and have fun

 

ps.. not worried to much about decarb... unless i'm doing stainless ( and that is in foil packets, so i don't care )... leave it a tad thicker and just grind off the decarb... no biggy !

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Great kiln David, I really like the overhead door. I've got the same one as Dave Stephens and I love it. I was wondering what the length of your kiln is.

 

Thanks

Steve

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I second the salt thing. Once you go to salt, scale is something that happens to other people. You can pretty much go to final grind and first buff before you do the HT with salt. And once it's hardened, it should be able to be tempered in that electric rig without too much in the way of support- it's not going to get saggy at 450 or 500 the way it will at 1550F.

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