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Thread: Results of drying bowl blanks.

  1. #1
    Join Date
    Jul 2018
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    Knoxville,TN.
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    59

    Results of drying bowl blanks.

    After several weeks, with rainy every day moisture, two bowls (unpainted) are firewood the other four have minimal checking. Those are the two with Anchorseal applied. I believe they have not reached ambient moisture or equilibrium moisture content (EMC). The 100 watt bulb was to hot for the 30 gallon can size. They just dried too fast. Going to try boiling the next ones for one hour and drying in a brown paper bag for three weeks. This is a method off the internet. It recommends this with success. I am in a hurry because I have little storage for blanks or green bowls. Roger.l

  2. #2
    Join Date
    Oct 2008
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    Kapolei Hawaii
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    Did you follow the other drying bowl blanks thread? I posted in there about my fridge kiln. I followed Cindy Drozda's design, and one of the keys I think is using 3 different wattage bulbs. I start with a 40, 55 and 72, I think. A 100 watt would be even hotter...... May use one in the future. Using the different wattages allows the wood and kiln to heat slowly. Of course a fridge is way bigger than a trash can...... Maybe you could start with a 25 watt. Yes, I do get cracks, but not that many I recall. I like it. I have a batch in there now that I have to check on. Oh, in addition, I turn the light off, and let the fridge cool slowly to ambient. Unsure if this is needed, but I'm lazy and a weekend turner, so I let the fridge cool for several days.

  3. #3
    Join Date
    Aug 2005
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    Midwest
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    2,043
    How about using a dimmer switch with a 72W bulb and turn it up a little every couple of days or so?

  4. #4
    An stc-1000 dual temp controller can be found on ebay for under $15. Its easy to wire. Connect your heat source to the heat connection and a fan to the cool connections. You program the temp you want to hold and how many degrees the swing is and it does its thing switching between heat and cool. I use one for my home brewing hobby and it works great.

  5. #5
    Join Date
    Aug 2011
    Location
    Lummi Island, WA
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    665
    A couple of questions - how thick are your blanks, and where did your first batch crack (rim or base).
    I haven’t found any magic pills to speed up drying. Have you considered turning to finish wet? Some magical things can happen depending on the species. When I get a load of wood, I plan to spend the first several days roughing, coring, boiling and stacking blanks. Then they go on wire shelves until they’re ready to turn. Turn a few wet to see how the wood is reacting, then wait for the rest to dry slowly. I tend to leave them in the boiling pot for several hours.
    After a few rounds of this the shelves are really well stocked and there’s plenty to choose from - wet or dry, whatever you need.
    If they’re cracking at the rim, make sure you round off any sharp or even square edges. Reed Gray even wraps the rim in stretch wrap to keep them from drying too quickly.
    Everyone’s experience with drying is a little different, geography/weather/humidity/species, thickness of the blanks, consistant wall thickness all enter into the process, so its difficult to take someone else’s experience from the web and expect it to work for you. Putting them in paper bags where I live ( the Pacific Northwest) creates the perfect microclimate for mold.
    Have you looked into local clubs - they’re full of guys trying to dry the same stuff you are. Most are more than willing to share advice.

  6. #6
    Join Date
    Jul 2018
    Location
    Knoxville,TN.
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    59
    Hello, my rough turned bowls are one inch thick as much as possible. The two unsealed bowls cracked on the wall in the middle. The openings where quite large. These two bowls where closest to the 100 watt bulb. I now am finishing drying the rest in silica gel cat litter bought at Petco. I am going to try boiling when I can. Roger

  7. #7
    Join Date
    Sep 2015
    Location
    San Diego, Ca
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    1,647
    I agree with Chris. These inexpensive temperature controllers work great. The instructions are woefully lacking but they work great.

  8. #8
    A much smaller bulb would help for a 30 gallon kiln, 15 watt even. It can depend a lot on the woods. Any existing cracks will get a lot bigger, and if you don't know, make sure the pith is gone.

    robo hippy

  9. #9
    Join Date
    Feb 2016
    Location
    Walworth, NY
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    103
    Maybe some of the smart people here would be able to develop an affordable, refrigerator size RF kiln. Vacuum and heat - no problem. The RF I believe is the stumper.

  10. #10
    Join Date
    Apr 2018
    Location
    Cambridge Vermont
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    I work with some eggheads who truly understand RF (bot not closely with them). What I know is probably more than most but it's a tiny fraction of them. I've always thought that what would work well is getting a magnetron or two from a microwave oven to provide the energy to get the water molecules vibrating. The problem is that the vacuum chamber needed would need to be made out of something without iron (aluminum, stainless steel, glass, etc.). That would get expensive unless you could find something used.

    If you would like to try this looks like a good option.
    https://www.ebay.com/itm/Best-Value-...s8~:rk:57:pf:0

    It's a 15 gallon aluminum vacuum chamber with a plexiglass lid. I think, but more research would be needed to verify, that the energy from a microwave oven's magnetron would pass through the plexiglass but be trapped inside the aluminum. You would need to make a metal cover to keep the microwaves from leaking out. Being 15 gallons a 16" bowl would fit inside. Probably $400 for the chamber and a small pump and an old microwave oven would be enough to try it out. I'm sure that if you stuck with it you could have a really good way of drying blanks fast with little damage. There's more details needed but I think it would be doable.
    Last edited by Alex Zeller; 03-02-2019 at 2:02 PM.

  11. #11
    Join Date
    Feb 2016
    Location
    Walworth, NY
    Posts
    103
    Alex, You are probably right: It is doable. But not by me, at least not yet. I don't know enough about microwave propagation to feel comfortable working with it, so until an expert on the subject comes along, I won't reinvent the wheel for safety reasons. How about a microwave inside the vac chamber? I'm not even sure of the RF frequency used in the kiln. I did use a MW transformer for the pyro thing but I discontinued that action because if you make one mistake it may be your last. Wasn't worth it. Maybe just vacuum and heat would work.

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