DIY Science Equipment

  •     Our differential scanning thermal analyzer uses phase changes to identify unknown materials. It applies heat to two chambers: one with a substance and the other empty, and measures the temperature in the chambers. By comparing the graphs and identifying spikes in temperature, you can tell what the sample is made up of. For example, a sample of water might show a temperature spike at 100˚C, or paraffin wax might change states at 25˚C. A mixture would show spikes at both locations. The tool can be constructed from materials accessible in Rwanda, and the cost in the US was well under $50. Other thermal analyzers of this type start at $20,000, so ours is 1/400 the cost of its next­-lowest competitor. It requires only simple tools: a toaster/Nichrome wire, clay, electricity, and tape that can withstand high heat. We are hopeful that, in Rwanda, our device will assist in improving chemistry labs.

  • This precision balance is made entirely of commonly-found material, and was designed and built without the use of any CAD software. It is a torque balance, operated as follows:

    First, one places the mass one wishes to measure in the plastic holder on the left side of the balance. Then, the nuts on the threaded rod on the right side of the balance are moved along the rod, to the right if the non-calibrated mass is too heavy, and to the left if the non-calibrated mass is too light. Then, the radial distance of the nuts is found by averaging all the distances of the nuts from the fulcrum (this can be read straight off the attached ruler). Then, one performs the math below in order to obtain the mass of the non-calibrated object.

    Here's the math necessary to work the balance.

    First off, let's call the mass on the left side of the plank, the mass that we want to measure, m_n, for non-calibrated mass. Then, the force of gravity on this mass is F_n = m_n * g, so the torque of this object relative to the fulcrum of the balance is T_n = F_n * r_n, where r_n is the radial distance relative to the fulcrum. We know that r_n is a fixed constant, because we want the non-calibrated mass to be right in the center of the left side of the plank. We can say that the plank has length R, so r_n  = 0.5R. Then, we know that T_n = F_n * 0.5R = m_n * g * 0.5R.

    Now, let's look at the side with the calibrated mass. The way I designed the balance is for it to have movable nuts on a threaded rod, so the total torque on the calibrated mass side is the average of the torque of each separate nut, so if we let the mass of each nut be m_i and the radial distance of each nut be r_i (where 0 < i <= total number of nuts), then the total torque on the calibrated mass side is g * (∑_[i = 1]^[number of nuts] {m_i * r_i})/(number of nuts) = T_c.

    In order for the calibrated mass and the non calibrated mass to be perfectly equal, we need to have the torques be equal. Thus, we need to equate our expression for T_c and T_n.

    Now, we have that T_c = T_n, so g * (∑_[i = 1]^[number of nuts] {m_i * r_i})/(number of nuts) = m_n * g * 0.5R.

    All of the quantities in that newest equation are defined except for m_n, so we solve for that.

    Thus, we have that m_n = (g * (∑_[i = 1]^[number of nuts] {m_i * r_i})/(number of nuts)) / (0.5 R).

    So, to operate the balance just right so that the masses are balanced, we need to adjust the cart on its slider along the track so that its radial distance relative to the fulcrum makes the equation come out just right. Thus, all someone would need to do to operate the balance is move the slider until the two sides of the plank are perfectly balanced (to the naked eye, which means that they will only be *very close* to perfectly balanced), and then solve the equation for m_n. 

  • Kepler University, located in Rwanda, is a relatively new private university that has partnered with MIT in order to further its students' education. Unfortunately, in Rwanda, science equipment is rather hard to come by, and when it is available, it is very expensive due to fluctuating inflation rates. Thus, MIT took on the challenge to create DIY science equipment for the students of Kepler. One of the most common-- and the most important--laboratory instruments is a precision balance. I chose to create one from easy-to-find materials for the benefit of the Kepler students.

    Iteration 1:

    The first iteration of my balance is a simple balance with some upgrades. Like a normal balance scale, it consists of a plank with a fulcrum in the center. However, the left side of the plank has a track in it for a cart to move left and right. This is to even out the torques of the two masses on either side. This iteration was modeled on a picture of a balance that does not have the problem of a plank balancing on a 2-dimensional line, which would be the case if the fulcrum were a perfect right triangular prism. The model for this iteration had a toilet paper roll stand, with a pencil for the fulcrum (the friction produced by the pencil was very large and very inconvenient), and a toilet paper roll for the balance plank. A track was cut into the roll and a piece of cardboard, glued to another piece perpendicular to the first one, was place into the track. The friction on the track was also an obvious problem.

    Iteration 2:

    This iteration of my balance was a slight renovation of the first iteration. A toilet paper roll was used for the stand again, but this time it was reinforced with even more cardboard. Instead of using a pencil for the fulcrum, I used a screw that started out smooth and cylindrical but then tapered to become serrated. This reduced the amount of friction between the balance “rod” and the fulcrum. I also used a CD cover for the base, which allowed for a small amount of stability, but not as much as desired. For the weight-system side of the balance, I used two L-shaped supports as the basis of the system. A threaded rod went through the top hole of each L-shaped support, and was held in place with a nut on either side. Several nuts were placed onto the threaded rods (to be used as calibrated weights) before fixing the rod in place with end-nuts.

    Iteration 3 (Final!):

    First, I chose a metal bar for the balance "plank". This metal bar was aluminum, so it was pretty easy to drill through, as opposed to, say, steel. Then, I found a large cuboid of wood, which would serve as the support for the balance. The balance is situated at about eye level for a person seated on a relatively medium-height chair. Originally, the bar supports were supposed to be L-shaped and made from steel-- however, I found right-triangle-shaped supports that had two holes, evenly aligned, and made from some type of alloy. They were actually a little bit heavier than the L-shaped ones but that seemed to be fine, since these are much more supportive than the L-shaped ones. Then I obtained small Tupperware cups to use as the stationary box for the un-calibrated mass. I drilled a hole in the bottom of one of the cups so that I would be able to affix it to the balance rod. I drilled holes for the M5 screws to hold the support system to the balance. Then, I screwed in the supports and put a threaded rod through the holes. I rolled on a few nuts to act as weights for the threaded rod. After that, I drilled a hole through the wooden cuboid, and cut it down so that I would have a support for my balance rod. However, the weight system (with the supports and the threaded rod) proved to be extremely heavy, so I fixed that with the following modifications. I cut down a thinner threaded rod to the correct length (11 inches) for my system. Then, I replaced the really heavy and long M5 screws, which were 60mm, with much smaller 40mm screws. This reduced the amount of weight accumulated on the weight-system side of my balance. After that, I replaced the supposedly "more supportive" triangular supports with lighter L-shaped ones that were smaller. This further reduced the weight on the weight-system side of my balance. In the end, I found that the entire weight system, including screws, weighed near 80 grams. This was much smaller than the original 100-ish grams of the previous weight system. Now, I realized that the cup on the other side of the balance was far too heavy. I decided to drill more holes in the balance rod to allow for more flexibility with the un-calibrated mass's torque. Also, I reduced the number of nuts that were screwed on to the end of the screw that holds the cup in place on the rod. This finally allowed my balance to actually...balance! The balance happens to be very sensitive to changes in torque--the nuts on the weight-system side of the balance would tip the balance either way if they were moved even a few threads left or right. Though this increases the accuracy of the balance, it is slightly time-consuming to move the nuts back and forth. However, this balance had no base, so I added one. The base was a set of four small planks arranged in a spiral shape to stabilize my balance. Also, I designed a ruler for the calibration system in Rhino. I laser cut the ruler that I would use for calibration. Then, I glued it to the weight-system side of my balance. However, this offset the balance of torque between the two sides of the balance, to the extent that I was not able to remedy this simply by moving the nuts on the threaded rod. Thus, I added two more nuts to the screw holding the Tupperware cup in place, and that solved the problem. My balance is finally finished and functional!

  •     In this studio, our goal was to create lab equipment out of inexpensive and accessible materials and objects for a lab in Rwanda. Our project focused on creating a differential scanning calorimeter/thermal analyzer. This is a device used in chemistry experiments to analyze thermal properties of a given material.

        The device heats two chambers (one holding a reference material, one holding the material to be analyzed), then takes the temperature of those materials as they go through state changes. 

        During the first few days, we focused on the heating aspect of a differential scanning calorimeter. Initially, we thought that a clothing iron would provide the type of heating components we wanted; it could get extremely hot, and it's accessible in Rwanda. Our first concern with the clothing iron was that it wouldn't provide even heat. This is important because the amount of heat given to the two chambers must be even or else the experiment is invalid. We tested this by placing two cups of water (in Pyrex) on the front and back of the iron and timed the boiling point. However, there was a very clear problem: the water did not boil. We figured out that the Pyrex cups were too heat resistant and wouldn't allow the water to boil. However, when we got the temperature of the actual iron, we also saw that it was hot, but not as hot as we needed. Our goal temperature was 300 degrees Celsius.

        At this point, we started looking at other possible devices that we could take apart and use for our project. We decided to use Nichrome wire which is found in most devices that heat up, especially toasters. We were able to combine this Nichrome wire with metal struts, frequently used in construction, and clay for thermal insulation. This equalizes the heat coming into the chambers but keeps them thermally isolated. We built this thermal chamber and wrapped it with the heating panels from a toaster. In an early iteration, the panels would sometimes touch and short­-circuit. For our final iteration, we layered clay between the panels. This solved the problem entirely.

        In our final iteration, we also lengthened the wires to the heating circuit, raised the entire differential scanning calorimeter above the ground, and used color-consistent clay.

     

  • Intro:

    Our goal was to design do-it-yourself science equipment for use in a science lab at Kepler University in Rwanda. We decided to make lasers using the red lasers from a DVD burner. The students at Kepler could make them, and then do experiments with the speed of light, as well as wavelengths of light. In the end we used purple lasers from MIT, but the students at Kepler may be using the DVD lasers instead.

     

    Circuit:

    The circuit for our laser pointer took up most of the time in the two week period. In order to use a laser, one needs to create a driver circuit to ensure that the lasers receives a constant current and voltage. We used a solderless breadboard and a potentiometer to start, but soon realized that a resistor and solder breadboard could be used instead. Our final circuit is soldered to a small breadboard and velcroed to the project enclosure. The circuit provides a constant voltage and amperage, giving the laser just enough power for it to light up. Because the circuit and battery do not provide that much power, out laser is not very bright but that could easily be fixed if we had more time.

     

    Enclosure:

    The enclosure was originally thought to be a sheet metal box. We realized that it would be hard to make that, so we decided on using a project enclosure from Radioshack. The box is composed of a plastic box and lid, with an aluminium plate on top. There is a hole drilled into the front for the laser diode to go through, as well as a slot for the switch. Our enclosure makes the laser pointer into a perfectly sized handheld device that can be easily opened for repairs, and battery replacements. The electronics are attached to the box using velcro, making them easily removable. While this box helps to make the laser complete, there are some problems with it. The main part of the project box is thin plastic, making the whole product feel cheap and slightly flimsy. Because the box is so small, we also had a hard time getting the electronics to fit in it. Now the electronics are in the box, but the wires are bent in weird ways in order to fit that could result in a short circuit. If we had more time we would work on making a new box from scratch, but for now this works pretty well.


     

    Final:

    Our final product is a laser pointer enclosed in a modified project box. There is toggle switch located on the left side which turns the laser pointer on and off, and the laser beam comes out of the front. The enclosure is a project box from Radioshack with holes in it. The box is composed of a plastic box and lid, with an aluminium plate on top. Our final laser pointer is creates purple light, but it is not very strong. Because of this we would have tried to make a red laser pointer so that we would have a more intense laser pointer if we had more time. All in all our final laser pointer is great for the amount of time we had to work on it, but it could be better.

  • In Rwanda there are no lasers for use in labs. Because of this the students at Kepler cannot do any experiments related to the speed or wavelengths of light. Our goal was to make a laser pointer out of parts that can be found in Rwanda. Even though we ended up using lasers that will need to be imported, the idea was to use lasers found in DVD burners. When the coaches go to Rwanda this summer they will be able to show the Kepler students how to make the lasers, allowing them to experiment with what they can find out from the lasers. We hope that these lasers will be able to help the students explore new things throughout their science education, and that they will be able to create and fix the lasers in the future.

  • We built a three-step water distiller. Water is boiled in a pot on an electric burner, the steam that is created goes up through the tube and into the coil system, where it is then cooled by a constantly-cycling cooling system, built using tubing and a windshield wiper system from a car. The re-condensed steam then flows out of the nozzle at the end to be collected, cleaned of any unwanted elements. It is built primarily out of hard and flexible Poly-Vinyl Chloride (PVC) tubes. The other materials include hose clamps, epoxy glue, a motor-pump, a power source, and rubber tube caps. This distiller can efficiently clean water for use in science experiments or consumption.

  • We began by thinking of designs for an efficient distiller as well looking at possible materials. We decided it would be a good idea to use a teapot to boil the liquid, because teapots are easy to use and easy to obtain. We had a few ideas for cooling methods. One idea was to have a chamber for the steam to be caught in and cool down before it drips into the water container, the second idea was to have a coiled tube to give the steam time to cool and condense into the cup. We were unsure of what type of material to use for the coil.

     

    Eventually, we ended up temporarily ruling out hose for piping because of the possibility of contamination. After that we spent a lot of time thinking of material ideas. We then got down to making a prototype for our project. We used a standard teapot with thin plastic tubing that was affixed with tape. After heating the water in an electric heater we poured it into the teapot. After a few minutes the plastic tubing started to melt and bend so we turned it off and started to think of other ideas. We also noticed that the steam was having a hard time travelling through the connection between the first and second tubes. We thought about using bigger ones or fixing the connection.

    We moved on, and attempted to build another iteration of our design. This time we used more heat resistant flexible pipe to attach to the teapot mouth. We still used electrical tape, as we had not figured out a proper method of connection. We then attached smaller tubing for the coil portion of the design. We set it up with the teapot on a griddle on the floor. The HR tube (heat-resistant) bent up from the teapot to a slightly thinner tube that was coiled around a table leg. After a few minutes of boiling the water, we didn't see any steam getting to the coil portion. We changed the setup a bit so the teapot would be on the table and the pipes would aim down under the table. We tried this for a while but the water kept condensing a few inches out from the teapot mouth. Eventually we turned it off and started to think of ways to push the steam further out. We decided that we need a better heat source and possibly smaller/different tubing.

    We then attempted to fix the heating problem by using a hotplate instead of a griddle. We got much more steam to gather and a little bit of condensation. Ultimately, the tubing was too hot because the heat was spreading and distributing itself along the entire pipe. We decided we needed a cooling element in our project, so we took a larger pipe from the workshop and fit it around the smaller tube (where the steam/distilled water would flow.) We drilled a hole in the bottom of the pipe and put a very small tube in to give the water a place to filter out. Then we found an old windshield wiper pump and put the tube from the pump into the top of the larger tube. The very small tube ended in the pump’s reservoir, creating a simple reciprocating cooling system. When we tried the design again toward the end of the day we used an electric burner which heated up much faster, and got much hotter. We saw a lot more steam coming through the tubes. As for the cooling part of the design, it did bring down the temperature some and help with condensation. However, the water was still letting off a good amount of steam when it reached the bowl we put at the end of the pipe.

    We wanted the tube inside the hard-wall pvc cooling chamber to be coiled in order to prevent any more steam loss, and so we thought about ways of doing that. In order to release the most heat, we decided to use metal pipes for the coil, and insulated plastic for the bend from the teapot. We then considered whether bending steel pipe for a coil would be viable. We tried bending 1” steel pipe, but we were incapable of creating a coil. We decided to not continue using the water reservoir we had used previously, is it was too small for any workable coil. Throughout this, we also worked on finding different tube sizes in order to fit the teapot.

     

    After landing on using copper piping for the coil, we started straightening and bending the copper tubing into a coil by hand (not easy!), and then we went about affixing it into the hard-wall pvc. We also bought and attached two rubber caps for the hard-wall cooling chamber. We bent the copper out of a hole we drilled in the pvc in order to create a nozzle for the recondensed water to flow out of. We also drilled a new hole for the coolant outflow. We sealed both with epoxy.

     

    We needed to make some edits to our project. Firstly, we bought an aluminum pot for heating the water in, as we could drill a hole of any size into the lid. We set our new iteration up in the shop and filled the water tank almost to the top before boiling the water in the pot. We set the pump at 4 volts to keep a consistent level, filled the pot with water, and clamped it down so minimal steam would escape through the cracks. When we turned on the power, the burner eventually reached around 500 degrees celsius. The steam went through the tubes and condensed relatively quickly, but there were a few leaks in both the cooling and main pipes. After 20 minutes, we had about a quarter of a glass of water.

     

    We started fixing the leaks in the pipes. We used epoxy to fill the space in between the overlapping pipes so that no water could leak out. We then tested the distill with regular, dirty, and salt water to see if the water could be thoroughly cleaned, no matter what was in it. Throughout each test, we had to continuously tighten the tube clamps that held the tubes together in order to prevent leaking.


    In our final design we built a three-step water distiller. Water is boiled in a pot on an electric burner, the steam that is created goes up through the tube and into the coil system, where it is then cooled by a constantly-cycling cooling system, built using tubing and a windshield wiper system from a car. The re-condensed steam then flows out of the nozzle at the end to be collected, cleaned of any unwanted elements. It is built primarily out of hard and flexible Poly-Vinyl Chloride (PVC) tubes. The other materials include hose clamps, epoxy glue, a motor-pump, and rubber tube caps. This distiller can efficiently clean water for use in science experiments or consumption.

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