glass kiln modification

samuraistuart

samuraistuart

Joined
Dec 21, 2006
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I thought I would share this, just in case someone now, or down the road, might need the info. I recently acquired a glass kiln, top loading, with elements in the lid. It is 110V, so takes about 1 hour to reach 1500F. I had some concerns about being able to take a blade out and get into the oil quickly, and safely...with the elements on the under side of that lid. I was using a wire of sorts to hook into the tang holes and lift out and into oil, since I didn't have a long set of tongs. Even with long tongs that have an angled head......opening and holding that lid while trying to quickly pull a blade out and into the oil in the proper orientation is not fun. It is do-able for sure...just not ideal.

Then I got to thinkig of making a modification to allow easier/faster handling. There is already a peephole on the side wall of the kiln. You can take out the peep hole plug and it has zero effect on the temperature. I thought I would cut a slot from that peep hole, down to the floor level of the kiln, very thin...just thick enough to slide a 1/4" thick blade into (if I ever made one that thick). The cut was a rectangle shape, measuring about 5/16" wide by 1 5/8" tall, with the round peep hold on the top of the cut. Looks like a golf ball on top of a tee. I cut the aluminum (I think?) casing with a dremel wheel....just because I could....and then cut the firebrick with a hacksaw blade (without the frame). I've never cut the stuff before. It almost falls apart!!!!

There is no problem at all, as I figured there wouldn't be. I was just apprehensive about doing it. It is warming up nicely this very moment. I have a CruForge V blade to normalize and austenitize today. I have a piece of Kaowool over the homemade hole while it warms up, just in case. Now I can simply slide the blade in and out......lickety split. I know this doesn't really help a whole lot of people, but maybe someone can use the info down the road.

Thanks for ALL that ALL of you do here!
 
Interesting concept I hope it works out for you. Just out of interest does your Kiln have a power interrupt switch on the lid? i.e. does it shut off the elements when you open it? If so your mod would circumvent this (unless I'm missing something?). I guess you just have to be careful not to bump an element! ;)

-mike
 
Mike, no I don't think there was a switch to shut the power off when opening the lid. It stays on. I just did a normalization on a blade of CFV this evening. Hardening will be done manana. My mod worked PERFECT. Even WITHOUT the kaowool covering my "slit", the unit loses ZERO heat. Not one single degree. When a cold blade is put in....it does indeed drop about 8-10 degrees....and recovers in a only few seconds. The hole has no effect on temp. This is a HUGE improvement over lifting the lid, jacking around with the lid while trying to catch a blade on the line....and dunking the fish in Parks 50. Now, it's slide in....slide out. Basically no temp change......and NO time differential waiting for temp change!!!! This totally negates me worrying about bumping into an element on the lid, and worrying about time loss to the quench. I am "Happy Happy Happy" to quote Phil Robertson.
 
Sounds like a good idea, how close is the T/C to the knife? to make sure you are getting a solid reading.
 
I've got the normalizing done on this particular blade. I need to harden yet, and when I do I'll post pics. The thermocouple is fairly close to the blade. I have checked the temp with two different pyrometers. At first, I thought the temp was 15 degrees hotter than the readout, but I was wrong. With a brand new digital readout w/thermocouple, it reads exactly what the kiln controller says. The kiln came with an analog needle display to show temperature, and it too shows exactly what the kiln controller says. I am very confident in the temp settings. The other day I hardened a blade, and while it was soaking, I placed both the digital and needle thermocouples directly onto the blade itself, and got the exact reading of the kiln controller. This thing is amazing. Even without the peephole plug in place, and my slit wide open (that sounds just all kinds of wrong :eek:), the temperature doesn't move.
 
Pics, as requested!!! Not much of a modification, but it makes a huge difference not having to open the lid now. No problems whatsoever with heat loss, even without the peep-hole plug in place, and no kaowool covering the slit. I like the needle thermometer with ceramic shielding on the thermocouple!SAM_1159.jpgSAM_1164.jpgSAM_1165.jpgSAM_1166.jpg
 
Yes it was, much less expensive. And it was right down the street in a storage facility. Lady had passed away, and the kids were doing an estate sale. Thanks, it is a great solution to what was bugging me!
 
Nice, I have seen a few of those at a decent price on craigslist might have to keep my eye out for one. Thanks for posting pics
 
How are you putting the blades in and out of the kiln? How long are you leaving them in the kiln?
 
Stacy, The blades go in and out of the kiln now in the slot I made. It's just an open slit that can be covered if needed, but honestly leaving it open, and the peep hole open, does nothing to temperature inside. How long do I leave them in? Whatever the heat treat requires. For example...I have a blade I just made out of CFV, and needed to heat treat. The kiln does take a while to reach temp, but when it does, I slide the knife in my new opening, edge vertical, leave just enough of the tang sticking out to grab it. Crucible recommended for CFV steel to equalize at 1200, ramp to 1500 or 1550 and quench. After a normalization (yesterday), and once the kiln was at 1200, blade went in. Temp dropped about 10 degrees according to the digital controller (and I have verified temperature with a digital and analog thermocouple), because of the cold blade, but went back to 1200 within seconds. I had it programmed to hold at 1200 for 15 minutes, and then ramp up to 1500 and hold for 10 minutes, then I quenched. Now it's interesting you ask, Stacy, because my big concern now, going from a forge to a kiln (especially one that takes 20 minutes to get from 1200 to 1500) is DECARB DECARB DECARB. Satanite is useful in this situation. I left the edge thicker than normal on this CFV blade, and I just finished sanding the decarb out (after an initial temper at 350). At first, I was getting nervous, because the file bit right into this steel after quench and it was at room temp. I had ruined a previous blade of this steel because I ground the edge WAY too thin, and the decarb was deep, because I was new to this kiln and put it in cold and let it warm up. Not this time. I was surprised at how much steel came off before I hit the hard stuff. Like sanding off a soft layer of san mai. I had the edge at .035, and after sanding decarb it is around .010. I came across a thread where a guy had the same problem, he thought his Cru Forge V blade, or the heat treat he did, was bad, but it turned out to be decarb. He was getting super soft Rockwell readings,and had to sand .010 off of each side before hitting 66 Rockwell.
 
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