Is a DIY Heat Treat Oven Worth It?

S

SLC_Blades

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Aug 20, 2018
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So I’ve been looking into building my own heat treat oven for some time now so that I have the ability to work with stainless steel. I’ve recently had to move and this has resulted in a whole new (and improved) workshop for me. Unfortunately, the location will prohibit me from using my forge. This situation is even more of a push to acquire a heat treat oven but before I do so I’d like to ask a question to those that have already done this.

Is the money you save by building your own oven worth the work? I’m in no position to fork over the money for an Evenheat, and consider myself capable of tackling the project. I’d just like to ensure that it isn’t more complicated or demanding than I think it is.
 
In my opinion, it isn't worth building a HT oven for stainless. It is better to purchase a good unit with a great controller.

Save your building projects for forges and grinders. That is where you can save serious money.
 
It was totally worth it for me. And I find it just as easy if not easier to ht stainless so I'm not sure why the particular alloy makes a difference. One thing I wish I knew before I started was that the type23 bricks soak the water right out of the mortar, so it is a good idea to soak them in water before assembly. I built the steel shell an inch or so larger than the firebrick structure and back-filled with vermiculite.
 
I tried to build a large volume 240v oven once, and i almost ruined $100 worth of bricks because i didnt mortar them properly and they cracked and got shitty. The oven did not hold up. I cleaned up the bricks on a disk sander (which made an ever loving mess) and reused the bricks for smaller ovens and they work fine now, but man what a pita.

I didnt do enough research. I figured mortaring bricks was a no brainer. It wasnt.
 
Stacy E. Apelt - Bladesmith said:
In my opinion, it isn't worth building a HT oven for stainless. It is better to purchase a good unit with a great controller.

Save your building projects for forges and grinders. That is where you can save serious money.
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I think opposite way , Stacy .It s worth to build HT oven .Worth if you want to make it to spare some money and worth if you want for same amount of money as purchased one HT oven , to make much,much better one . Of course if you know what are you doing . . .
 
EChem237 said:
One thing I wish I knew before I started was that the type23 bricks soak the water right out of the mortar
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Randy3000 said:
i almost ruined $100 worth of bricks because i didnt mortar them properly
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You do not have to use mortar These soft bricks hold the heat fine without mortar. I built mine for @350 and I would say it was worth it to me.
 
Building an oven can definitely be worth it, IF you do it correctly. If not, you'll end up wishing you had just bought one.
JTknives built a very nice one a while back, that probably ran him close to what an entry level evenheat or similar would cost, but it looks to be a much more capable oven as well.

Building an oven for stainless and similar tool steels will be more expensive, just due to the cost of the controllers alone, especially if you get into some of the fancier touch screen and other programmables. You'll also be running your oven for much longer periods, at moderately higher temps (2000F vs 1500F) which will potentially take its toll on your bricks, mortar, elements, etc... a little faster.

That said, if you're really wanting to do stainless, you'll want to tool up for cryo tempering as well. This means at minimum having a dewar and the ability to fill it. LN is not necessarily cheap or available in all areas. For what LN would cost me, considering the amount of knives I make per year, it's generally just as cost effective for me to send them to someone like Peters, get guaranteed results. Not that I couldn't get those results, but again, I'd still need LN, a dewar, stainless foil or a gas setup, quench plates, etc...
 
I thought for a while about building one and read tons of wips. I eventually just bought an evenheat and absolutely love it. I wish I would have just purchased it a long time ago. I personally couldn’t have built one this nice.
 
Building something makes more sense to me after you already own the item, know what you like and dislike, and understand how it works. I’d have no problem making another oven, or new grinders now that I have them.

Warren
 
Spalted said:
You do not have to use mortar These soft bricks hold the heat fine without mortar. I built mine for @350 and I would say it was worth it to me.
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In fact, many extremely large (by our standards) kilns are build with hundreds or even thousands of dry stacked (not mortared or fastened together) soft firebrick. This is advantageous for the ability to move the kiln, but also, because without careful control of cooling, mortarted brick are highly likely to crack, regardless of how you mortar them together.

Most commercial pottery and knife kilns don't mortar them either, with the exception of things like doors, where they need to be locked together (and where they usually crack).


I'm kind of in agreement here, I wouldn't jump into building a kiln, unless you're familiar with the components, processes, have tools and the experience to fabricate such. It wont save you money, it'll probably cost you more. If you had the prerequisites, you probably wouldn't be asking us anyway.

Buy an Evenheat. Even myself, who's built a couple, and retrofitted numerous others, am constantly tempted to buy a new Evenheat with a TAP controller. They're hard to beat for the money, especially if your time is any factor at all.
 
I will weigh in on the mortar issue. I feel that it is not a good idea to mortar the bricks together. They are designed to seat against each other tightly. A physical "frame" to hold them snug is a good idea. Some folks just run 1/4" threaded rod through them and snug down with nuts on fender washers.

I completely agree with Warren that buying and using a kiln/grinder/tool and learning what its strengths and weaknesses are first will make a custom built kiln/grinder/tool a more worthwhile project.

One thing that gets left out on many kiln build discussions is a 1" kaowool insulation blanket around the bricks.. This will make the oven much more efficient … and much cooler on the outside.
 
I couldn't agree more with Stacy. I'm building one myself and it's been in works for a while now (don't get must time off work) but I'm using a similar approach. No mortar, basic steel frame out of angle iron and sheet metal and a few layers of kaowool around the bricks. I'm using one inch wool but would probably use a couple of layers and pack everything together so the bricks do not move at all.. The dealer I spoke to said that kaowool is relatively inexpensive and is worth investing to make the oven more efficient.
 
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