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  1. #46
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    Here's a few pics of my solar kiln, fairly simple arrangement, (using the KISS principle) recycled shower screens, a fan out of a range hood and some ply, generally the idea is to separate the stack from the heated air (and the direct sun) but then direct the heated air thru the stack to be heated again in a continual loop.
    As it is I only use it for already dry stuff say <20% that way distortion is minimal and I can get MC down to single digits, if I were to use it to dry wetter stuff there needs to be a greater level of control and complexity which may or may not happen?

    I have measured 50°C in the kiln, so if ambient conditions were 25°C and 50% RH but inside the kiln at 50°C RH would be about 13%, even if it were 25 and 80%RH ambient in the kiln it would be about 20% RH, it only takes a short while to lower the MC of thin veneers.

    open kiln.JPGclosed up.JPGplenty of room for veneers.JPGrear of stack.JPGairflow baffles.JPGhot airflow baffles.JPGwith the glass front.JPG


    I use 7x7mm as stickers, I was using cardboard, which was OK but had a few issues, also note the stacking at an angle at the back, I do this to try and get even airflow thru each layer of the stack.


    Pete

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  3. #47
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    Thanks Pete.

    That helps. Can you tell me how big is the opening at the bottom of the piece of angled ply behind the stacked veneers?

    Cheerio!

    John

  4. #48
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    Quote Originally Posted by John Samuel View Post
    Thanks Pete.

    That helps. Can you tell me how big is the opening at the bottom of the piece of angled ply behind the stacked veneers?

    Cheerio!

    John
    The idea of the baffles is to force all the airflow thru the stack, so the piece of ply that comes down behind the stack should only be as far as the top of the stack.
    In use though I find it doesn't seem to be too critical, I have put a stack in with no baffles and still got results, when I setup the kiln last week I was wondering what these extra bits of ply were for and put them aside thinking that they must be for something, looking at the pics has reminded me.

    It is one of those things that if there is adequate flow thru the stack to take away moisture that's all you really need to do, a good even breeze felt on the back of the hand is all I go by, adding ply to the sides of the stack is possibly the first move to increase airflow if it feels a bit light on, if airflow still has plenty of velocity as it comes down the back of the stack it will more likely take the easier path thru the stack rather than reverse direction and go over the top of the stack, to a large degree it depends on the dimensions of the stack.

    Too much airflow can be detrimental if the air is taking too much moisture away too quickly or if the timber is a slow dry timber where the moisture moves slowly to the surface, this getting more into the area of wet timber though.



    Pete

  5. #49
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    You may recall the resident shop fool read the tape wrong resulting in the frame under this cabinet being a tad undersized. Rod Gilbert was unkind enough to notice the goof. Just to jog your memory, here it is as delivered.

    IMAG0585[1].jpgIMAG0584[1].jpg

    Well, my conscience would not allow me to leave it as it was, especially given that since the wood show I once again had stock of camphor laurel in the shop (being out of wood was my excuse for not fixing it at the time the goof was made). In addition, I had recurring nightmares of Rod telling me how the legs were not "out there" the way they should be. So, wandered over to my sister's place, pulled off the legs and frame and made a couple of small modifications . It was returned to her today, as noted in the following pics.

    Rework 1.jpgRework 2.jpgRework 3.jpgRework 4.jpg

    It looks much better, like the cabinet is sitting on a plinth. All I did was copy the "plinth" design from the coffee table finished last week.

    OK ... hopefully I can again sleep like an innocent.

    Cheerio!

    John

  6. #50
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    Thumbs up

    Good one John!!

    Had the sister noticed or complained??

    If not then I ask "What would Rod know?"

  7. #51
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    Quote Originally Posted by artme View Post
    Good one John!!

    Had the sister noticed or complained??

    If not then I ask "What would Rod know?"
    Sadly, Rod was correct. At the time I had no more timber and decided to finish it.

    My sister thought I was crazy when I told her I wanted to remove the base and replace it (I did manage to rescue the legs), but saw the wisdom in this decision when it was returned yesterday. Much prettier.

    Cheerio!

    John

  8. #52
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    Pjt

  9. #53
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    PJT et al,

    Regarding veneer dryness ...

    In our earlier discussion on this thread you suggested the veneer was better a little too dry than a little to wet, and I agree. However, on another job I was fixing veneers that featured a large knot, as seen in the pic.

    Attachment 417820

    These veneers had dried out very thoroughly, and because of the nature of the wood, they were crazily buckled and warped. Any attempt to flatten them when dry resulted in cracking and breaking. I got them on by wetting them a little so they would flex and flatten in the vacuum press.

    But you guessed it, they dried out again when out of the press and they warped a little. I wet them again and covered them so they would dry out very slowly as well as to create even moisture content throughout the veneer. When they were flat again I mounted and lacquered them. So far, all is well ... they have not moved again.

    I should have wet both sides, and I should have ensured that the veneer on back and front of the doors was the same ... lesson learned the hard way.

    However, could I have used something other than water to make these veneers flexible enough to put in the press? I was thinking of paraffin oil or a clear decking oil finish. The PU glue would not be impacted by such finishes, as it works well with greasy wood.

  10. #54
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    The following article on flattening veneer from Joe Woodworker I think will answer your questions.

    Flattening a Veneer with Veneer Softener

  11. #55
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    Thanks, Bohdan.

    I note that even this product can find thicker veneers difficult (mine are 2 mm), but it looks like a very good place to start.

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