Introduction: Dehydrator Oven 1.0
I’m a student of electric engineer and for one of my projects of Electronic laboratory, I build my own dehydrator oven, and I made it using recycled materials as well some scraps of wood that I had from another thing I build, I took me some time, but it has become a real treasure because we have been using it since then on daily basics, of course, the electronics part were made with pieces borrow from the lab or even the teacher, and since on my country those are not easy to find, I have to give them back, but I find the way to adapt the oven to work a stable temp, with thermostat with a lower temperature that the proper electro domestic had, maybe if someone asks for it and I had the time, I can make a part two explaining how to make the temp control for it (using a Triac and optocouplers ) but the way it’s now it works smoothly at 65 Celsius degrees and that is a basic temp for most of the fruits or vegetable to dehydrate.
A Dydrator oven evaporated the water from the food, with the help of a continue heated airflow and depending on the fruit or the vegetable that you want to dry out it will depend on the time that must spend the fruit in it, but it's one of the best ways to preserve food, and once you have made it ti will become an extraordinary helper to dry out seasonal fruit for example or even make your own flour.
Step 1: Twisted Metal Time...
I used a couple of cans of oil to make the interior of the oven, with the help of an angler grinder remove the top and the bottom and make the cut on the side if you don’t have that tool you can use a metal saw or even a can opener
Then I grab a rubber hammer and on a block of wood, I started hammering all the previous angles that it had and made it a smooth plank of steel if you don’t have a rubber hammer you can use several wood planks and use a normal hammer over the steel, the point of this is not to “hurt” the steel with the rude contact of the rubber or the normal hammer.
Once you had it done with the help of a table bend the plank in 3 parts, of course, this will be the inside part of your oven so think it carefully, when I did it, try you make use of a couple of old fish grill’s that I had already I took its wide as a standard measure: 34 cm and that left me with 30 cm for the sides, think it better I could have cut the wood the same sides but since I didn’t want to waste any wood (was large of the plank of wood that I had xD) you can use the same rubber hammer or the towels and the iron hammer to help you bend the plank with the side of the sturdy table, and since we still need the top(36 x35 [cm]) and the front door we need to cut the other steel sheet. Yep the whole side of the oven it’s made to fit this old grill, so evaluate what you had and make it work, so if you want to replicate this project make it work for what you had.
I decide that the inside cabin will have 25 cm tall, so the 10 cm I marked and cut it, as seen on the image to bend that part to the inside and over there will rest the toaster iron, that provides the heat to the oven…
The other sheet of steel was cut to fit the front door (37 x 30[cm]) and top of the oven (37 x 35[cm]) the sheet for the door was nailed to it while the one on the top was bent over at the corners like the top of a present box so it fits perfectly on the steel cage that has (30 x 34 x 30) [cm]) and with the leftover part of the sheet you will cut the strip for the missing fill of the cage that the side panels lack
Step 2: Chop Chop Wood Time
Then you have to cut de wood that will become the exterior of the oven and remember that those pieces will have to fit like on a puzzle game, so take extra care, and those were really easy to cut with a jigsaw or scroll saw, use what you have.
Back: 1.5 x 37 x 40 [cm]
Top and bottom: 1.5 x 37 x 34[cm]
Sides: 1.5 x 37 x 34 [cm]
Front1: 1.5 x 37 x 40 [cm]
Front2: 1.5 x 37 x 10 [cm]
The small front panel it’s on the base of the oven and will help to fix the door on its place, cover the cables of the resistance, hold the switch (on and off) as the led that will let us know if the oven its turn on, Well with the big front door panel, you will cut and made a handle with the extra 15 cm that it had, it will help you take out its place and since that door will be on the ovens it needs to have the inside cover with the steel sheet, use tacks to keep the steel on its place
Step 3: Drilling Time
A friend was going to throw his old “tostiarepas” because it fell and break down and I was beyond saving (the structure at least). But the iron sheets and resistance was fine, the thermostat was dead, but since I was making a project were I would control the temp it was simply perfect. I know many of you may have never seen an “Arepa” on your life and have been wondering, the most curious one had even Google it by now, well it’s not a big deal it’s a breakfast or dinner dish made of cornflour, water and salt, something like a tortilla but with overweight problems, but here is as common as a sandwich is it for you, and yes of course an old sandwich maker would be perfect for it if you have a tester you can check out if the resistors are fine with just doing a continuity test.
Next, you would have to make a lot of holes on those iron sheets so the air can flow through them, if u have a drill press it would be really easy if not well it will become a little tedious job, and of course, is necessary to make sure that you don’t drill over the resistances or the cables! So be careful to dismantle those (or move them aside as I did), drill as many holes as you want they will be helpful to let the airflow, remember then that’s the principle of dehydration
On the green ellipse you will see the original thermostat (10 A/ 250 V) I move it to one of the side panels of the oven and replace it with one of lower temp limit that way the oven won’t reach an excessive temp
Then you will have to get the measures of the irons sheets and built a base for it with the excedents of steel that we left on the steel sheets, and with the help of the sturdy table, just bending at the sides the same way you did before to get the sides of the full oven and with a big nail and the hammer make more holes on the sides of the base, so air can flow better.
Then with the jigsaw, you will have to open a couple of holes on the wood, you can help yourself with the drill, and if you have one of those drill bit used for doors, your job it's halfway done (I didn’t), of course, the holes are for the computer fans that I got for my old pc and for a couple of broken power sources, the point it’s to make the circle for the fan to collect the air if it’s on top or to push air inside the oven if it’s the bottom fan (in this case I use 2 fans on bottom one for each resistance) and with a nail you will make the starter holes for the screws that hold the fan in its place
Step 4: D-oven Assembly!
Remember there is a vacuum fan on top so you will have to cut a hole on the steel sheet exactly on the place where it goes, and the easiest way to do it assembling the oven without the top wood making use of the steel angles and the screws
As you can see on the graphic the position of the angles that will hold the oven, to make it easy to locate I thought about a color code, so the red ones are the ones that go outside the oven and will hold the wood ceiling, the blue one go inside and will hold the steel cage, the gray ones will hold the steel cage and the purple will hodoor (Hold the door)
With the oven assembled without the wood ceiling attached, you can draw the hole made on the wood on the steel sheet corresponding to the ceiling and with some nails and a hammer start opening a path and help yourself with the jigsaw if you have one or with scissors that can cut metal, be careful the sheet is really “soft” for the jigsaw so hold it firmly, so it won’t bend over with de move of the drill.
On the picture, you will get to see the angles on the top but is because the whole oven was assembled for testing on the lab, the purpose is for you to see the hole where the fan will go on top
Step 5: Power Up!
To power up the fans, I took one of the old computer atx and made use of its internal transformers, you can see how to do it by looking at one of the Instructable a guide like: https://www.instructables.com/id/ATX--%253e-Lab-B... .....we are not going to use a lot of the voltages, just the 12v and the main current (when I was working with the circuit for the control of temp I need the other voltage inputs but for this basic oven it doesn’t matter) just identify those and make some extensions, the main power must be made with heatproof cable or normal cable with a protective cover since it will have to move from inside the oven to the switch and back to the source where we will have to sold those on the current input.
That atx had a switch (must be able to withstand 10 Amp at least) and it will be moved to the front panel as well the led that the original “tostiarepas” had,
The cables for the fans are made with the leftover pieces of the of the same atx
To hold the ATX source to the oven, drill a couple of holes on one of its base and the help of a couple of screws, you will have it firmly attached to the back panel of the oven.
Step 6: Finishing Touches
With the "legs" of an old couch, it will stand on its own, and they are just like a big screw, so it's very easy to put them on if you don't have those around make ones xD after all if you are seriously thinking on making this it will be a piece o cake.
Attach the ceiling of the oven with the angles, properly place the fans, when I said this it's because of the top fan will work as an extractor of the air and the bottom ones will get the air inside, don't mess up the airflow...
Place the grills inside and put the cut-up fruit on it, or wherever you need to dehydrate (once I help dry a paper-mache project on it, a mask) and put a timer on your cellphone to remind you to check the progress ( the original project had a timer too, after all, it was an electronic lab) for example I know that a whole pineapple takes like 8 hours to get dehydrated, and leaves like 2 hours, bananas take 16 hrs and so on... but this knowledge will get to you through experience because the amount of fruit will make it change.
Hope you make it, don't hurt yourself on the process and if you had any questions feel free to make them...
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