Home Made Kiln

Discussion in 'Woodturning Discussion Forum' started by Emiliano Achaval, Feb 13, 2017.

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Do you have a home made kiln?

  1. Yes, I find it very useful.

    85.7%
  2. I do, but I never use it.

    14.3%
Multiple votes are allowed.
  1. Emiliano Achaval

    Emiliano Achaval

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    I found a flower "Lei" display case. Its the same as a beverage display case, with glass in the front. The engine still runs, but the air its not cold, temperature goes up to 74.5. On the inside, on the ceiling there is a fan that moves the air, recirculates it inside. I'm thinking if I drill a hole above it from the outside the fan might help me with the drying process. I have read Cindy Drozda PDF on her kiln. She doesn't say how big her holes are, or how many, and where... A friend told me make them 4 inches wide, one above, one below, and have the light bulb below. The case is very tall, like over 6 feet, only 2 shelves, I will add a few more.
    So, my questions are: how many holes, both sides?, opposites sides, what size holes? Is the fan inside too much air movement? I have called an appliance repair guy, he will disconnect the motor. The door has a nice light, but fluorescent, and I dont think it gets hot enough... Most people seem to be using a 60 watt incandescent light bulb... I searched the forum and did not find anything about this...
    Since I got into box making, want to make sure my wood is dry, and I want to dry wet wood faster... Thank you in advance for your response. Aloha from Maui
     
  2. charlie knighton

    charlie knighton

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    Look for thrown out dishwasher, you can have mine if you come get it
     
  3. dbonertz

    dbonertz

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    Emiliano,
    I would like to see a picture of the case you are referring. Having not seeing it you can drill 2" holes in the side towards the top and bottom. You don't have to use all what you drilled by making a cover for them. Rotate the cover for full open to partial open. The fan inside is a very good idea to keep air moving over your blanks. This helps to stop mold from developing and helps keep surface moisture from staying on the wood. My dehumidifier kiln, albeit much larger, has three fans in it.

    A light bulb heat source is an Ok method however those types of incandescent bulbs needed will become obsolete sooner rather than later. You can pick up a small 120 amp oven heating element for around $15. Just make sure sure you mount it safely as not to start a fire. I have mine mounted in an old metal computer case. Hook it up through a thermostat for better heat control. The light bulb method works just make sure you keep it 1" off the bottom so any water that accumulates won't cause a problem.

    Just to give you something to compare to my kiln is 8' wide x 3' deep x 7' tall and has insulated 2x4 walls, head and floor. I also use a dehumidifier.
     
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  4. Dave Delo

    Dave Delo

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    Not sure if this will help you but here's a couple pics of a kiln I did for some powder post beetle critter elimination on cherry lumber a few years ago. 1/2" plywood skin lined with thin insulation panels from the big box store. I used a couple 250 watt infra red bulbs with a fan on one end & on casters for mobility. Drilled a hole in one corner for any water drainage and sealed it up with a rubber stopper. Made a little plexiglass observation window so I could see a few different thermometers stuck in a piece of scrap lumber that would read internal lumber temp. This box held just shy of 100 bf on lumber.

    [​IMG]
    [​IMG]

    [​IMG]
     
  5. John Torchick

    John Torchick

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    Nice project, Dave. My problem is having enough space for something like that or even an old dishwasher.
     
  6. Emiliano Achaval

    Emiliano Achaval

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    Thank you for your reply!! Today I drilled 2 holes at the bottom, 2 at the top. Each is 1 5/8 wide. I will take a picture tomorrow... I had to still light bulbs from my house, and related them with LED, went to ACE hardware and they dont sell old light bulbs anymore!! Someone suggested a heating rod for inside a safe... Will that work? So you think the fan on the ceiling is not too much air flow? Cindy drozda has 2 one inch holes below, and 2 above... Appreciate your help. Aloha.
     
  7. Emiliano Achaval

    Emiliano Achaval

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    Nice one!! But... I can peek into mine! LOL. Love the glass door... Interesting choice of lights! I guess they are not too hot?? Is that heating lights? Thank you for taking the time to answer. Aloha
     
  8. Emiliano Achaval

    Emiliano Achaval

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    What's the optimal temperature that I'm looking for? And humidity... Thanks.
     
  9. Emiliano Achaval

    Emiliano Achaval

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    Sorry, I didn't read before my first reply. I will try those infrared light... And... you have a window!! Aloha
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Infrared lights are made for things like keeping food hot at restaurants. They might be OK for baking wood to kill bugs. It looks like the meat thermometer is reading 180 degrees. I think that would be way too hot for a drying kiln. For a box of the size of yours I think that an oven lightbulb Would be about right. They are specialty tungsten with a rating of about 40 watts. They are still available because CFL and LED lights wouldn't survive long in an oven. The temperature should be warmer than outside air, but not blazing hot.
     
  11. Emiliano Achaval

    Emiliano Achaval

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    If is not too much trouble, could you take a picture of the heating element box and thermostat? What is the ideal temperature? Thank you in advance!!
    Great tip Bill!!! Just love this AAW forum... I will post pictures of my contraption tomorrow. Aloha
     
  12. Bill Boehme

    Bill Boehme Administrator Staff Member

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    You might check with your fellow Islander, Kelly Dunn. He uses a kiln and says that is the only way that most wood can be dried in the humidity there. Fortunately, I don't have to do anything special beyond putting some Anchorseal on the wood.

    BTW, Kelly is currently out of pocket, off to the mainland to attend his daughter's graduation.
     
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  13. Emiliano Achaval

    Emiliano Achaval

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    I rough turn most of my work. Then it goes on a shelve for a minimum of six months... Super bone dry here is 12.4 %... I dried some apple wood in the microwave in the house. Wife almost kill me, lol, but thats another story. The apple was bone dry. Then we had a Kona storm. It actually gained some weight back! So, I dont think it makes sense to worry about drying too much, unless you have to send it to the mainland. Then it is a good idea to throw it in the kiln, get it out, and run to the post office... Cindy Drozda actually texted me back and told me how her kiln is... I have never felt the need to dry the wood, but now i'm chasing threads daily, and the wood has to be bone dry... I'm off to Hilo for the opening of the 19th annual woodturning exhibition. I will be doing a demo on chasing threads. I'm sure I will see Kelly, I will ask him about his kiln... I appreciate your help Bill. Aloha
     
  14. Emiliano Achaval

    Emiliano Achaval

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    Just went out to check my kiln. Seems to be working. 82.5 and 24% humidity. Took some pictures.
     

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  15. Richard Coers

    Richard Coers

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    Glass is a very poor insulator. For more heat and less energy spent, cover the unit with a shipping blanket or insulation blanket. I usually start all my drying at 90 degrees then build from there. I also have a small desk size fan for air circulation.
     
  16. John Torchick

    John Torchick

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    How about a fan from a computer tower? Or frost free freezer?
     
  17. Zach LaPerriere

    Zach LaPerriere

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    As for lightbulbs—you can usually get 60 or 100 watt rough service bulbs at most hardware stores. I don't know much about kilns, other than talking to a few small operators. Most kilns for lumber work between 120 and 180° F.

    An alternate to heat is to remove moisture from the air. I use a 10' X 12' insulated shed as a kiln of sorts...and I don't use heat, I use a dehumidifier. I see that wood dries faster with heat, but in my experience drying bowls of softwoods and softer hardwoods, I don't want to dry them too fast. But that's just me, and my conditions and wood species are very different from yours or anyone else on this forum.

    One things is for sure: monitor your wood carefully. Nothing worse than ruining a bunch of blanks. Do some experimenting on blanks that aren't special to see how far you can push it. As an example, I've learned that I can dry mountain ash in roughly one quarter of the time of hemlock. Strait grained mountain ash is almost impossible to crack, and hemlock will crack in mere hours in a dry room. It's an adventure!
     
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  18. Mike Brazeau

    Mike Brazeau

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    An article on mine is at http://ghwg.ca/techniques/Mike_Brazeau_Simple_Drying Kiln.pdf
    Here is some data from a presentation I put together a couple of years ago. Basically start at a low temperature, allow humidity to build as high as possible and then start raising temperature. Holes for circulation should not be too large, so humidity can build. Temperatures in Celsius.
    IMG_4398.PNG
     
  19. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Those would both be good.
     
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  20. dbonertz

    dbonertz

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    Sorry it would be difficult to get a picture of the heating element. I have a tunnel in the back of the kiln where it is and the fans blow over it. I would have to dismantle a lot of things to get a picture of it. I heat mine to 95 degrees to start. as the wood dries I will go to 100, 105 until dry. If there are bugs, eggs or larvae then run it to 120 to 130 for two days, after wood is dry, and that will kill any insect issue. With my kiln a try to pull a gallon of water a day. Smaller kiln less water per day. The wood area in my kiln is 6' x 2' x 6'. You can calculate that square footage to yours and then run a calculation for how much water to pull every day from yours. At the end of the drying cycle the water pulled per day drops quickly that last week. I can dry a kiln load, depending on how wet the wood was when going in, in about 4 to 5 weeks. They are all bowls ranging in size from 18" to 7" in diameter. I have very little loss and what I do lose I can pretty much tell you as I load which ones I'll lose because they have a defect of some sort. I use a more expensive commercial thermostat on mine so It probably wouldn't useful to you. A household thermostat would work or oven thermostat. I don't know how big the fan is but I doubt not would be to much. Remember the kiln has a lot of humidity in it so the fan is blowing humid air around the blanks so it isn't like the fan is drying the wood it is just moving air around the blanks. You control the moisture loss by how much you open the holes or in my case how much I run the dehumidifier.
     
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