building a parabolic solar hot-water heater using 123d - clear mylar film roll
Once I had a set of dots, I made a 3D shape with 123D.
123D is a free, easy-to-learn Autodesk CAD software.
123D, I created a sketch and entered the coordinates of a point at a time.
Then I connected them with a thread.
This is the curve that defines the surface inside the plate.
I added more lines to complete the crossover
Part of the dish, then rotate 360 degrees around the center line.
Starting with 123D, I export my dish as an STL file and import it into 123D Make.
This is another free software for Autodesk, you can download the ator of Apple Mac-App-Store.
123D Make allows you to turn your 3d shape into a grid of 2d contours that you can cut out and combine together.
After importing my shape, scale it to the maximum size that I can make on the laser cutter, I chose the radial slice pattern.
I select the slice direction from the center of the dish (like spokes)
Up like a ring.
123D Make automatically calculates the grid profile I need and adds slots so that each piece slides into the correct position.
I started at 11.
A 36-inch diameter plate was made out of the cardboard as the prototype, and then a 36-inch diameter plate was made. 25" plywood.
The Nesting algorithm of 123D Make wastes material by placing too few pieces on a given paper.
I want to use most of my material to lay out the patterns, so after generating the laser sheets, I integrate them in corelldraw.
For 36 dishes, I had to split the largest rings into different parts, so I split them into corelldraw before cutting. (
Looking back, I will make the pieces of the interlocking lock into a jigsaw puzzle to add more rigidity. )
I cut the parts with 120 W 24x36 Epilog Laser.
For 36 "dishes, it will take about 3 hours to cut everything off. 25" plywood.
It is very important that your wood is completely flat on the cutting bed, otherwise the laser focus is not correct and the cutting is not good.
I use tape to help keep my leveling, but remember to level it when purchasing materials.
Once everything is cut, it's time to assemble. 123D-
Make makes a neat animation of how to assemble your dish.
I used a little hot glue to fix the first three brackets for this work, but after that, no glue is needed.
With enough friction, the dishes are perfectly combined.
Now that I have the mugs, I need a smooth, continuous surface to act as the inside of the plate.
I used a layer of masking tape and then used a few layers of spackle.
Fill the first layer of spackle in the depression of the belt.
I used a pre-
Cut the wood shape, rotate it and distribute the spackle evenly to the correct curvature.
I used a laser-
Stick a piece of wood to a piece of sandpaper and polish the surface to the correct curvature.
Once spackle had the smooth curved surface I was looking for, I sealed the surface with three layers of clear acrylic paint.
I considered epoxy and polyurethane but decided to use the acrylic because the acrylic has the least toxicity and the least environmental impact.
My next step is to add the adhesive-
Back the Mela film to the surface of the plate.
My science from green power (
They also have some great youtube videos about making solar parabola).
You can get the same stuff elsewhere with less money, but I know these things will work.
I can make my big plate with a small strip cut by a 24 "x 36" roll.
I cut about 1 "wide stripe with a knife and straight edge.
Then put them down and start with a strap through the center, working left and right.
Finally, I trimmed the excess around the edges and got ready for the first Test.
To test the performance of this parabola, I took it outside, pointed it to the sun, and lit things up.
I would like to know how small the area where this dish can focus on light.
Wearing dark welded goggles, I hold a piece of wood in the focus (
About 10 inch above the center)
And can let the light concentrate on the circle with a diameter of about 2 inch!
This means I get more than 250 times the ambient Sun Power!
Next, we try to bake marshmallow.
Unfortunately, they hardly cook.
They are too white to reflect all the light.
When we rub some black charcoal on one, when we put it on the beam, it starts burning immediately.
Always cover or put your mirror in the sun from a safe point of view, so it doesn't burn your house.
Try not to leave the mirror unattended in a sunny place.
The next step is to add a boiler.
I decided to use a circle of copper tubes for my boiler, so it functions like an on-demand hot-water tap.
I used 5 feet of the 1/4 tube.
No proper tube, I roll it up myselfbending tools.
I fill the tube with salt so it doesn't break and I wrap it around a series of smaller and smaller cylindrical objects until I reach the diameter I want.
Check out my instructions on bending copper tubes.
After finishing the coil, I installed it on a scrap pipe that passed through the center.
The diameter pipe is about 1/2/inch smaller than the inner diameter of the coil.
I filled the blank space with spackle and it will be used as an insulating material inside the coil.
Finally, I applied the coil with the coating of the black stove-paint.
It is very important to design paint for handling high temperature.
Without it, the coil reflects most of the energy we send out to it.
I drilled a whole in the center of the parabola and installed a pipe to hold the boiler with a laser
Disk of wood.
Two plastic hoses go through the center to deliver the water to the boiler and out of the boiler.
There is a needle valve to adjust the flow of water.