Chairshaker

Yes, it’s time for the doors. Friends who build things for a living have diplomatically suggested that there are better ways to build doors.  Building them in place was one of the suggestions. Thinking about it first was another. Both good suggestions. Anyway, the doors fought me to the very end but they did go on and are capable of opening and closing with out sticking.  So they’re on and now there’s two issues to deal with. A big crack that’s between the two doors, when they’re closed, and how to keep them closed. The answer to both issues turned out to be easy. The answer is to get some closed cell foam weather stripping. It comes in about 15 foot rolls and costs about 5 dollars. To use it open the doors about 5 inches. This will open the crack enough to stuff the weather strip into the crack. Then close the doors. Making sure the doors are open the same amount when you do this is important because when you close the doors they are not going to want to move at all. Then to keep the doors shut I just screwed through the top and bottom flange of the doors into the kiln itself. It sounds kind of ham fisted but the doors will only be opened and closed about 10 times a year so it isn’t going to be a lot of acumulated damage and screwing them shut closes the doors nice and tight. So that’s it. The doors are now closed and sealed. And now for the vent things on the doors. They’re the exhaust vents for hot wet air. Soon adjustable flaps will go on. In the mean time, however, there’s screening on the inside. Here’s why. During the day the kiln is gets really hot. 150 degrees is about average and air gets sucked into the kiln through these openings and then it flows out the upper vent openings. The upper openings are really for letting air in but without the fan running the air flow works in reverse and the downside to this is that every bug and dandelion seed along with everyone’s belly button lint gets sucked into the kiln and flows into the collectors on its way to the upper inlet openings. This is a bad thing. This problem showed up early in the building process so every night the kiln had to be sealed up tight. At first I ignored this problem of bugs and lint but after a few days all the nice flat black painted screening was jammed with bright reflective stuff.  Then, of course, when the fan starts to run the bugs and lint get sucked in the air intakes and the problem works the other way around. Either way you look at it putting screen on the inlets and outlets is a good idea. The world is full of bugs and it seems that everyone is packing around a big chunk of lint. So that’s it for this week. Next week The kiln gets loaded with wood and moisture sensors get attached to the wood. See ya then.

PS. For some reason all the pictures that go with this post will not load properly. I’ll try to get this figured out for next week.

So the fan that blew up the bag, that no one liked, has to be mounted inside the kiln. A  frame for a piece of plywood has to go in first, then the plywood gets screwed to the frame and then a hole gets cut for the fan.

You can see that the hole looks kind of strange. Extra wood was glued and screwed to the backside of the hole so the screws that hold the fan to the plywood have something to hold onto. There’s also 4 notches around the perimeter of the hole to allow bolts that protrude from the fan housing to pass when the fan gets shoved into place.

There’s a frame in front of the fan panel and it’s for a baffle to stop the air from striking the wood pile in just one spot. This may not be necessary and it steals 6 inches of room from the inside of the kiln so it may get chucked out, but for now it gets to stay.

There are no slots in front of the fan and all of the slots are in the bottom half of the baffle. This is so that the air gets forced towards the bottom of the stack of wood to be dried.

The slots don’t look very big but the area they represent when added together is larger than the area of the fan opening. In a test, the volume of air flowing through the slots was large. I didn’t bother painting this part because it will probably stay dry and it may also get thrown out so why bother. The power wire for the fan is sticking out of a hole in the front of the kiln. I’ll show all that in the post that shows the finished kiln. Next is the doors. See ya. next week.

Before moving on to the collector mesh aspect of the kiln please let me explain the previous post. Some people have asked what it was really all about, here’s the explanation. In the beginning, while I was planning to build the kiln, the conversation would always include the solar fan and how much air it could move. About 1000 cubic feet of air per minute was what I would tell people and they would always get that Ok sort of look combined with, what would that look like, kind of look. After a while I started to wonder myself. Would that fill a phone booth or a mini van and how could it be shown so everyone would just say “yes of course, I get it now”. So I made a bag. The bag in the video holds about 1150 cubic feet of air, give or take about 50 cubic feet.  It seemed like a good way to demonstrate the approximate ability of the solar fan to move air. What a mistake. No one thought it was a good idea. I would say, “hey I’ve got this idea and it involves making a large plastic bag that the fan will fill with air”. This would be met with fierce opposition. The arguments against the bag followed this basic path. The air resistance encountered where the fan was attached to the bag would be too great. The bag would be too heavy causing the fan to stall. Air pressure on top of the bag would prevent it from inflating and one person actually got angry and shouted that it was a stupid waste of time and would prove nothing. The only person who thought it would be a good idea was my dad. He was in the video holding the other end of the bag. The resistance against the whole bag demonstration was amazing and in the end we waited for a day when no one was around. Later, after it was all over and the bag was hidden away, I wondered if this was how the people who flew the first hot air balloon felt as their experiment was pitch forked to death. Probably. The bag is now in hiding, sends its apologies and it’s now time to move onto the rest of how the kiln was made.

This is the collector mesh. Dennis Scanlin and his students used a dark grey aluminum mesh for this but there’re two problems with that. One, it’s dark grey and won’t collect as much heat as flat black and two, it’s aluminum and that means really big money. So instead I’m using a very light gauge expanded galvanized metal mesh that’s used for stucco and false rock-work on houses. First, it’s not black but that can be changed with paint, and second it’s cheap.  Now it has to be cleaned and for that task TSP is the preffered cleaner. I won’t go into all the Blah Blah about how to be careful. Just read the instructions and follow them. This TSP stuff is made for cleaning off any left over manufacturing oils and greases that would prevent the paint from sticking. The mesh is supper bendy so laying it flat on the ground is about the only way to really scrub it with a brush. I didn’t feel like cleaning the ground as well so I laid out a big black tarp to keep everything dirt free. Sorry no photos of that or of the mesh before painting it. Before moving on here’s some info about tarps. Don’t buy them for this type of job. Go to your local building supply store and ask them for one or more of the old wrappers that cover the wood they sell. Chances are they have a bin full of them that they’re desperate to get rid of. So after scrubbing the crap out of the metal screen, rinse it off and then let it dry off on top of some saw horses. Using compressed air to blast off the water helps the process. From this point on try to keep this mesh stuff clean until it’s all painted. After the water is all dried off the next step is to prime the mesh with galvanized primer. Make sure it’s primer for galvanized metal. Then use flat black rust paint. After this is all done it’s time to bend it all into shape and stuff it into the collector boxes. The above picture tries to show the mesh inside the collector boxes. The problem, however, is this. Flat black painted mesh inside flat black painted collector boxes is a bad mix for taking pictures. I’ll try to explain the process. The mesh is thin and bends easily. This is good. The collector boxes are about 22 inches wide and the mesh is about 30 inches wide so you just bend the edges up on both sides, shove the mesh into the box and screw through the bent up edge into the sides of the box with stainless screws and washers. Use a 2×4 to help put a nice crisp bend in the screen. A picture of this would have been helpful. Sorry. I’ve put three layers of mesh into each box. Each layer of mesh is about 2 inches above the one below. As you add each layer the bent up edge has to be shorter or it will stick up above the sides of the collector boxes. To do this just cut a bit off or just fold the bent up edges over one more time to shorten them. The last layer of mesh should only be about an inch below the sides of the collector boxes. This is important. When the sun is just coming up or going down the sun is not shinning directly into the boxes. By putting the mesh close to the top of the box the sun will contact the entire top layer of mesh. More heat collection. The other thing to do is to bend all three layers of mesh at the bottom so the air flow will be forced to flow through all three layers at least once every time it circulates through the kiln. When you’re finished all this you’re going to have to add some support for the polycarbonate sheets. For this I’ve used strips of 3/4 inch ply wood at two points. The mesh was in the way so I just clipped it back with wire cutters and then air nailed the strips in place.  When you’re done with all this you’ll notice that the mesh and everything else is all scratched up and the screw heads are all shiny so grab a can a of flat black paint and touch everything up. Now it’s time for the glass. Before getting to that, however, you should know that I’ve decided that spending the extra money on real aluminum dark gray screen would have been worth it after all. The cost of all the paint and the time it took to paint the mesh I used is probably a good reason just to use aluminum mesh. Now for the glass. I said once upon a time that I wouldn’t endorse anyone’s product. Here I’ll make an exception. It’s not that I’m a huge believer in the product that I’m going to describe, it’s just that this one thing is difficult to get right and after tons of research it was the best I could come up with. If you know of a better product please tell me because I’m going to make another one of these things and it would be nice if there was something better to use. So here goes. The product is called “Sun Tough Poly”. It’ a polycarbonate product that resists UV, transmits as much light as glass and is rated to withstand temperatures of as much as 257 degrees Farenheit. These are all good things. Glass transmits about 90% of the light striking its surface. All other products only transmit about 80% so your kiln could be 10% cooler if you use something else.

It’s pretty easy to install this stuff. You just have to buy the special corrugated strips to support the top and bottom edge and there’re five vertical strips to get as well. The problem with this stuff is that it’s not very precise so getting a good fit is actually impossible to achieve without using silicone sealer. If you go that route it could look messy so for now I’m leaving it unsealed. Glass or the stuff that Dennis Scannlin used would have been better for getting a tight fit but I couldn’t get the stuff Dennis used and glass panels have issues as well. Ok, that’s enough for now. Next, a look inside at the fan installation. See ya next week.

The following story is based on true events.

One day a man holding a large plastic bag suddenly appeared in a farmer’s field. As luck would have it the farmer who owned the field was standing in the field at the exact moment the man holding the large plastic bag appeared. The farmer, as luck would continue to have it, was also looking at the very spot where the man suddenly appeared. The farmer was very cleaver and realized that for the first time in history something new, that other people would possibly later talk about, had just happened and so decided to begin asking questions. “Look here”, shouted the farmer, “what’s that you’re holding in my field.” The man who had suddenly appeared looked happy to have met someone so clever and replied, “It’s a very large plastic bag that’s to be used in an experiment”. No sooner had the man who suddenly appeared uttered these words than the farmer became hysterical shouting “How dare you suddenly appear in my field holding a very large plastic bag.” The farmer’s time of asking questions was apparently now over and replaced by arm waving, pointing and accusations of a wide variety. “Leave at once before my unstable and extremely crabby neighbour gets wind of this” shouted the farmer. It is a fact that unstable and crabby neighbours are also nosey, and so, no sooner had the farmer shouted this than the crabby and unstable neighbour did appear and immediately became more crabby and unstable than anyone had ever seen. The crabby neighbour wasted no time and lunged at the man who had suddenly appeared pushing him and his very large plastic bag to the ground. The very large plastic bag stayed quiet during all of this leaving the man who had suddenly appeared to do all of the talking on its behalf. “This bag means you no harm and we can all possibly learn something from it”, cried the man who had suddenly appeared. “Nonsense”, yelled the farmer and the crabby unstable neighbour. This unpleasantness continued for longer than all three of them cared for and in the end it was agreed that suddenly appearing with a very large plastic bag was probably not the best of ideas. It was also decided that the bag should be given a chance to prove itself. The bag had no objections to this and immediately began to swell. This was a bad move on the part of the bag. To suddenly appear with a man and then to begin swelling without warning was bound to cause problems and sure enough the farmer and the crabby neighbour became very worried and ran about screaming a number of things that made little sense and the bag, being dim-witted, miscalculated the danger it was in. The crabby and highly unstable neighbour began to hear voices which instructed him to grab a pitch fork and defend himself, which he did. The bag, suddenly realizing that things had taken a dramatic turn for the worse, began to move as fast as it could away from the crabby man. However, along with being dim-witted, bags are very slow when inflated and before anyone could learn anything of value the experiment was over. The man who had suddenly appeared knew a bad thing when he saw it and felt that leaving would be an excellent idea as the farmer and the crabby neighbour were clearly not ready to learn anything. And so it was that for the second time in all of recorded history something new, that people would possibly talk about later, happened. The man, who suddenly appeared, vanished. These two events happening so closely together and being associated with a very large plastic bag would in the end create big problems for people everywhere well into the future. There were those who believed that the man who suddenly appeared had never left. Others claimed that the man had only vanished with out first suddenly appearing. People everywhere believed one thing and not the other. Few could grasp that both things could have happened and of those that had this latitude of thought none believed that both events could have happened on the same day without someone somewhere learning something.

So this is it. The last look inside the heat chambers and inside the wood chamber before everything gets closed up. This is a shot of the heat chambers. Soon all four chambers will be filled with wire mesh that’s painted black. I’m hoping to find away to draw on the pictures that I’m using because it would make explaining things a lot easier. If anyone knows of such a program that doesn’t have a steep learning curve please tell me. The next picture is the back of the kiln looking into the wood chamber. Soon it will have bulkheads installed that will hold the fan. The rain is returning so the plastic is going back on and it’s monday tomorrow so the next posting will be next weekend. Before saying goodbye I should point out the four new small rectangular holes at the top of the back wall. These are the intake vents to let in new dry air. These vents will be adjustable just like the exhaust vents on the back doors. So that’s it, bye for now.