Drew Riley
Knifemaker / Craftsman / Service Provider
- Joined
- Oct 17, 2007
- Messages
- 4,236
One of the first things I did when I decided I wanted to start making knives, was to build a NWGS and a heat treating oven. It wasn't anything fancy... more/less just a chamber made from K23 bricks that I mortared together into the rough shape of a kiln, with a 3000W Kanthal element running along the sides. At the time, I didn't have much capability to easily fabricate a shell for the bricks to live in, and instead of a door, I just mortared some firebricks together that I would manually push in front of the opening with a piece of ceramic fiber blanket as a gasket to help seal things up. It did everything I asked of it for 12 years or so, but the bricks finally collapsed in on themselves, and I didn't want to waste my time or money repeating a "lack luster" design.
I've kept my eyes open for other options over the years, and I don't think I've liked very many designs nearly as much as the oven Jarod Todd (JTKnives) built a few years ago, so I drew inspiration heavily from his build.
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Bricks were SLIGHTLY easier to come by these days, than they were with my first oven build. I found a supplier/manufacturer about 25 miles away from me in South Holland, IL. The plan was to find somewhere close enough that I could pick them up and save about $100 to $150 in freight charges (and possible broken bricks), but UPS ground rate to my house was only $30, so I took my chances, thinking I'd just swap any broken bricks in person, if needed. Well, to my surprise, they packed things much better than I could have anticipated, with each individual brick in its own box:
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Here's how I set up to notch the bricks for assembly:
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My table saw took care of the cross cut easily enough.
The main chamber is 6 rows stacked like so:
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I decided to do top mounted elements on fused quartz rods, so I set up an angle iron fence and stop on my mill, and just used a 1/4" end mill to notch the bricks accordingly. I didn't take any pictures of that process, but here's the element after stretching it to length and spacing the coils:
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I didn't take too many more pictures of the build process, but basically I just lined my steel box with a 1" layer of ceramic fiber blanket on all sides, stacked in my bricks, laid in my element, and voila:
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I'm using the same controller box I built for my first oven (for now), though I do plan on upgrading to a touch screen/programmable PID controller in the future.
Some specs:
6x6x24.5" inside chamber (minus 3/4" or so at the top for the element, of course)
The element is a ~4000W kanthal element, running on 220VAC. It easily hits 1000F in 5 minutes or less, and 1575F in around 20 to 25 minutes
I ran it for 2 hours at 1575, and the outside shell had only reached about 130F.
After turning it off, I checked the shell a couple hours later, and it was about 200F.
Keeping in mind that the bricks are just press fit together, I'd say that's not too bad. I do plan on coating the inside with some ITC-100 to see if I can increase the efficiency just a bit, but as it sits now, it's quite usable.
I've kept my eyes open for other options over the years, and I don't think I've liked very many designs nearly as much as the oven Jarod Todd (JTKnives) built a few years ago, so I drew inspiration heavily from his build.
UntitledBricks were SLIGHTLY easier to come by these days, than they were with my first oven build. I found a supplier/manufacturer about 25 miles away from me in South Holland, IL. The plan was to find somewhere close enough that I could pick them up and save about $100 to $150 in freight charges (and possible broken bricks), but UPS ground rate to my house was only $30, so I took my chances, thinking I'd just swap any broken bricks in person, if needed. Well, to my surprise, they packed things much better than I could have anticipated, with each individual brick in its own box:
UntitledHere's how I set up to notch the bricks for assembly:
UntitledUntitledMy table saw took care of the cross cut easily enough.
The main chamber is 6 rows stacked like so:
UntitledI decided to do top mounted elements on fused quartz rods, so I set up an angle iron fence and stop on my mill, and just used a 1/4" end mill to notch the bricks accordingly. I didn't take any pictures of that process, but here's the element after stretching it to length and spacing the coils:
UntitledI didn't take too many more pictures of the build process, but basically I just lined my steel box with a 1" layer of ceramic fiber blanket on all sides, stacked in my bricks, laid in my element, and voila:
UntitledI'm using the same controller box I built for my first oven (for now), though I do plan on upgrading to a touch screen/programmable PID controller in the future.
Some specs:
6x6x24.5" inside chamber (minus 3/4" or so at the top for the element, of course)
The element is a ~4000W kanthal element, running on 220VAC. It easily hits 1000F in 5 minutes or less, and 1575F in around 20 to 25 minutes
I ran it for 2 hours at 1575, and the outside shell had only reached about 130F.
After turning it off, I checked the shell a couple hours later, and it was about 200F.
Keeping in mind that the bricks are just press fit together, I'd say that's not too bad. I do plan on coating the inside with some ITC-100 to see if I can increase the efficiency just a bit, but as it sits now, it's quite usable.
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