Reducing volume in Kiln for heat treating?

T

Taz

Knifemaker / Craftsman / Service Provider
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Apr 28, 1999
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Picked up an EvenHeat GT 14-6 for $150 yesterday! Did a slow trial fire (30 min on setting 1, 30 min on setting 5, then up to High until it reached over 1500) with it last night, got to 1510 and stopped because it was getting late. It has a diameter where I can put 13" blades inside and it's 6" or so deep. With the heating elements in the lid, I am wondering if I can make a new floor with some Kaowool coated in refractory so it's only like 3" deep so it would heat faster?

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When it was at temps and I opened the lid for a quick peak, it rebounded pretty quickly, it's just slow getting to temp. It is a 110V kiln and I will be adding a PID to it down the road as well.
 
I would do the kaowool pad so it was removeable. Wouldnt fire bricks just absorb the heat and take longer to get up to temp?
 
I agree with the Kaowool pad idea

You should consider converting that to ramp/soak with a PID controller, TC, and SSR. Connect the kiln power cord to the output of the SSR. connect a new power cord to the SSR and the PID. Set the kiln to its max setting and leave it there all the time. Turn on the PID and set the parameters. Ramp at 9999, soak for the desired time (eg. 15 min) Add the blade when the kiln gets to the target temp. Just realize that it will be slow in ramping.
 
I am planning to PID it very soon! It is only rated to 1650, so it will be for carbon steels, so I was going to skip the ramp version unless you think it would be helpful? I was going to let it get to to temp, add blades, get back to temp, soak as needed and then quench?

I will probably do KaoWool pad, coat with Greenpatch 421 and then plistix or itc 100ht to reflect the heat.
 
ITC0106VH Inkbird Temperature Controller Kit (eBay)
This is the PID kit I am looking at, does this look like it would work? I already have a 12" thermocouple from auberins and a digital reader, so I can use the better TC and the kiln also has a k type TC as well. I would add a plug and power switch to the box so I can plug the kiln into the box and yhe box into the power outlet (its a 110v kiln).
Can I do a layer of brick and then do the kaowool pad on top of the bricks to seal the area off (would have some hollow areas under the pad) or is it better to just do solid kaowool and coat the top?
 
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Yes, for what you want it can be simple PID. That Inkbird should work. You will need a proper type K TC. You want one with an 8 gauge TC and TC mounting block, as well as type K TC wire. Do an eBay search for "Type K thermocouple with Ceramic Block and extension wire" .

The wire and TC are polarized, so make sure you connect the TC properly to the PID.

We have been told by Spark to stop posting links to sites not associated with Bladeforums, so I modified you link in the previous post.
 
Thanks for fixing the link! I have the whole working k type TC 12" long with the ceramic sheath because I was going to use it in my forge. There is a peep hole in the kiln that fits my larger TC pretty well already, too as well as the opening for yhe original TC.

I may replace the TC in the kiln and use my other one for the forge so I dont have to keep swapping them out.
 
Here's why ramp/soak is important. For DET anneal, the steel you're annealing needs to cool from one temp to another at 550-600F. If your kiln loses heat FASTER than that, you need ramp/soak. For traditional anneals, the temp decrease per hour is sometimes 50F or lower. For this you NEED ramp soak.
 
It was up to 1510, I opened the lid for a couple minutes, then closed the lid. 90 minutes later, it was down to 750. 9-10 hours later in the morning it was still 95 degrees inside the kiln. If I was annealing, I would heat in the forge and stick in a bucket of ash. I am using steels that want a soak time, which is easier in the kiln than in the forge.

The forge has a large disc on the floor already, so I may elevate that with a couple fire bricks and put the koawool pad on that. Would I be better with something like green patch/Satanite or mizzou/kast o lite for the pad before I put the other stuff on it? I know satanite in thinner sections can crack fairly easily with weight on it.
 
I ordered the PID stuff from Auberins; figured it was better quality than stuff from Amazon. Went with a 6" 8 ga K type thermocouple, PID, SSR, heat sink, etc. I am going to run a female extension cord out of the project box to plug the unit into and the male end of the cord out to plug into the outlet. Is 12ga wire good enough for wiring the rest of the internals?

I put 3" of left over kaowool into the bottom of the kiln, added the kiln shelf to the top and did some samples last night. Started at cold, turned on high, 90 minutes it was at 1500 and 2 hours, it was at 1700!! Did some test coupons of 50100B and 1095 last night. 50100B was at 1500 on the pyrometer into Parks 50 and 1095 was at 1550 into Parks 50. 50100 came out nice, 1095 has slightly bigger grain, but still looked pretty good for my first attempts!

50100B:
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1095:
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