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Knuckleheads Wooden Box Kiln Build

ChinaVoodoo

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I have a safety concern with your build. A good friend who is an experienced builder and home inspector once told me that fans and rheostats are a hazard. I looked it up, and there is a specific type of controller that is used on variable speed fans. Otherwise it is a fire risk.

Take a look at this yahoo answers thread.
https://answers.yahoo.com/question/index?qid=20100723131008AAlILj9

Edit: alternatively, you could leave it on full blast and control airflow through restricting the inlet or outlet
 

Knucklehead

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I have a safety concern with your build. A good friend who is an experienced builder and home inspector once told me that fans and rheostats are a hazard. I looked it up, and there is a specific type of controller that is used on variable speed fans. Otherwise it is a fire risk.

Take a look at this yahoo answers thread.
https://answers.yahoo.com/question/index?qid=20100723131008AAlILj9

You're right. When it came time to buy the switch, I bought a ceiling fan speed control. I didn't use a light dimmer switch as I had originally planned. The fan is a bathroom exhaust fan.
 

Chicken

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looks like you really got a lot of room in that thing.
 

AmaxB

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I would change the thermal probe out for a thermalcouple http://www.ebay.com/itm/Extech-Inst...876?pt=LH_DefaultDomain_0&hash=item35dfc7ad44
the thermalelcouple is much more sensitive.
Just looked through the entire thread, you did a grand job on the kiln. Good choice on using a PID for temps it should work fine..... the first 4 or 5 runs play around a bit and take notes. I'm going to be putting my place on the market and moving to Maine. I'll be leaving my kiln here, so I'll get to build a new one!
 

deluxestogie

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I purchased the same digital controller (http://www.ebay.com/itm/281294885235), and just wired it tonight. The thermal probe is surprisingly responsive, and I believe it's adequate for a kiln or flue-cure chamber. This inexpensive little gem (only $15, with free shipping in the US) was easy to wire and configure, and it retains its settings when the power is removed. Since the relay will handle 10A/250V, it should have no problem managing even the largest of Crockpots. The settings and readout are in ºF.

I can't say that I'll miss my old water heater thermostat.

Bob

EDIT: Anyone interested in building a kiln, but squeamish about the wiring, here's a similar controller that is plug and play: http://www.ebay.com/itm/271782572156 for $30. Just plug it in, plug in the Crockpot to the controller's outlet, and set the temp.
 

Knucklehead

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I made a diffuser for the crock pot out of 3/16" acrylic sheet. I think I can more precisely control humidity by drilling holes. I moved the old cover handle to the new cover and it gave me an extra inch of clearance above the crock pot by eliminating the dome shape of the old cover.

new cover.JPG
 

Knucklehead

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Ah, well. I broke the diffuser plate trying to drill some holes out larger. I had sixteen 1/4" holes and only had the humidity up to 61%. I was drilling some out to 1/2" and the bit caught and broke the plate. I think the idea will work fine I just need a different material. Maybe lexan or aluminum sheet. I can cock the factory lid open slightly and get 73% but finding that sweet spot of slightly cocked isn't perfect. I was hoping to make a new lid and drill holes until I had a repeatable 67-68% with the lid closed. I've tightened up my temp tolerances slightly. On at 121F and off at 126F.
 
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deluxestogie

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It might be worth leaving the settings untouched, and graphing the temp/humidity every 30 minutes over an 8 hour period. My impression is that the higher the Watt setting of the Crockpot (Low, Med, High), the greater the swings in humidity. The high setting may actually boil some water, by the time the kiln temp reaches the set point. Your insulation is so good that a lower Watt setting may do well, and may stabilize the humidity (perhaps even with no lid in place).

Plan B is a cup a rock salt.

Bob

[Knucks thinks my tool selection is archaic. Does that qualify as on-line bullying?]
 

Knucklehead

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It might be worth leaving the settings untouched, and graphing the temp/humidity every 30 minutes over an 8 hour period. My impression is that the higher the Watt setting of the Crockpot (Low, Med, High), the greater the swings in humidity. The high setting may actually boil some water, by the time the kiln temp reaches the set point. Your insulation is so good that a lower Watt setting may do well, and may stabilize the humidity (perhaps even with no lid in place).

Plan B is a cup a rock salt.

Bob

[Knucks thinks my tool selection is archaic. Does that qualify as on-line bullying?]

I don't have big swings in humidity, I've been getting a 1% humidity difference between the on/off set points of temperature. The problem is getting the lid cocked in the same exact position each time after removing and replacing the lid. I just figured that drilling enough holes to get the humidity right with the lid closed would be the most repeatable way. Right now humidity is 69%, so I cocked the lid just right this last time. If it's open just slightly more than I have it now, humidity will stay around 72-73%. With the lid off, it climbs too high.
 

Jitterbugdude

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I just got promoted to chief kiln inspector (CKI). I will be down in 2 weeks to inspect it. There has been a policy change this year though. Payment is now expected in cigars, wine and women.. :rolleyes:
 

Knucklehead

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I just got promoted to chief kiln inspector (CKI). I will be down in 2 weeks to inspect it. There has been a policy change this year though. Payment is now expected in cigars, wine and women.. :rolleyes:

That's good news.

How about cigarettes, moonshine, and Playboy magazine?
 

Knucklehead

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Humidity has been climbing a couple percent a day. Switched the crock pot from high to low to see what effect that has.
 

ringanator

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I am a newbie and I don't know much about the ageing process but seems to me that maybe 2 systems will better control heat/humidity a heater on a thermostat and a humitiastat controlling a humidifier maybe even one of those cold humidifier won't affect temp that way you could control heat and humidity independent
 
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