"Good intentions will always be pleaded for every assumption of authority ... the Constitution was made to guard against the dangers of good intentions. There are men in all ages who mean to govern well, but they mean to govern. They promise to be good masters, but they mean to be masters." - Noah Webster

"There is no worse tyranny than forcing a man to pay for what he does not want just because you think it would be good for him."
-- Robert A. Heinlein

Saturday, October 16, 2010

More on The Dehydrator

I previously posted about building a dehydrator/incubator here.  Turns out I didn't need to use it as an incubator because one of the hens went broody, and so now we have two new baby chicks.

Even yesterday, I placed a thermometer inside the box with just the acrylic cover on it, and the sun got the inside temperature up to over 120° F, even with the cool wind blowing around.  But until yesterday, I hadn't yet made the screen frames to make the box useful as a dehydrator.   That's what this post is all about.

Step one was to take several old scrap boards of 3/4" thickness and cut them into the pieces for the frames.  Precision cuts were not that important, so I simply used my left forefinger at the leading edge of the footplate on my DeWalt circular saw. (I hate when people don't use the proper names for tools, but that's the subject for another post.)  Now, I'm a firm believer in safety, and I like to wear gloves to prevent splinters.  Make sure that something like what you see in the first picture doesn't happen to you.

Anyway, trying to be efficient, I cut and assembled the first prototype frame and put it in the box to check my measurements and comfort in insertion and removal, and then I cut all the rest of the wood for the number of frames that I would assemble.  All of the long pieces are 20" and all the short pieces are 14".  More on that later.

 I had bought the 1/4" square hole screen at the same time that I bought the panel of foamboard.  I'm a little proud of myself for having calculated in my head to within a single square foot of how much screen I would need.  A 48" x 60" roll of screen (4' x 5') was just enough to make the 9 frames that comfortably fit in the box. I used angled tin snips to easily cut through the screen.  Then I realized that I wanted to fold over the short edges of the screens where they would be exposed to handling, thus preventing scratches.  This is most easily done before stapling the screen to the long members of the frames.

The gloves are really important for comfort here. Using one of the cut boards as a "brake" to start the fold, you crease the screen along the edge of the board as you see in the picture.  Once you've done this down the entire edge, then you can complete the fold without the board.

I used a standard manual staple gun to fasten the screens onto the long boards, trying to get each staple to straddle two strands of wire.  The staples were more than 1/2" deep, so I needed to tap them a little with a hammer to make them tight. This would be important when fastening the long boards over the short boards. You want the screen finish to be nice and taught.  In order to make sure of that, I didn't just drill my pilot holes straight down through the corners of the boards, but rather I drilled the holes at a slight angle, so that when the  screws drew tight, they would also pull the screen a little tighter.

It may look like I'm drilling straight down in the picture, but I'm not.  I used weather proof deck screws to fasten all the corners together.   The opening of the box is 24" x 16" x 16" deep.  So, I wanted the frames to use the most space but still be easy to move in and out of the box.  So the frames needed to be  20" x 14".  That gives me two inches of gap on each end of the short ends of the box and an inch on each side of the long sides of the box.  By overlapping the long boards on top of the short boards, a gap of about 1½" is created between each screen, which should allow sufficient air circulation between layers of food being dehydrated.  You can see the horizontal gaps well with the frames stacked out of the box.

This work on the frames took about four hours, and that's because I was figuring it out and making decisions as I went along.  Such is the nature of prototyping and pattern making.  I will also admit that I have yet to discover what the effect will be with 9 fully loaded screens of food inside the box.  I'm sure that the temperature will not get as high as it would with the empty box, what with the absorption of heat by the food itself.  I may have to put spacers between the frames and decrease the number.  It could also be that the temperature will simply rise much slower but still get up to a rather high level.  I will have to monitor it carefully and I'm sure that I can adjust the temperature by how much of an air gap under the clear acrylic sheet on top.  I'm chomping at the bit for Sunday, so I can slice up some apples and start the test drive. Can't do it today because it's Shabbat.  But I will try to remember to come back to this and let you know about the results.
Moxie did not appear too impressed seeing the finished products in the box.  She is too interested playing the grand protector of the chicken realm.

She proved herself quite well yesterday as Twyla reports over at Green Acres.

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