Commit e53ade8d authored by Edwin Manuel Alvarez Valdivia's avatar Edwin Manuel Alvarez Valdivia
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week11

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<h3>Week 10</h3>
<p>Molding and casting.</p>
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<a href="construction.html"><img src="images/thumbs/construction.png" alt="" /></a>
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<a href="week11.html"><img src="images/thumbs/inputs.JPG" alt="" /></a>
<h3>Week 11</h3>
<p>Input devices.</p>
</article>
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<h1><strong>Hello!, I am<br> Edwin Alvarez</strong><br>
<a href="aboutme.html">About me</a>.<br>
<a href="finalproject.html">Final Project</a>.<br>
<a href="contact.html">Contact</a>.<br>
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<h1>Input devices.</h1>
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<p>
For the assignment of the 11th week: Inputs devices, it will be divided into 4 parts: Sensors, Board, Programming and Download.
</p>
<p>
<h2>Sensors</h2>
Sensors are devices that measure different variables such as: temperature, pressure, distance, presence, etc.
Most of these sensors are analog elements, since they can measure up to infinite possible values, for example the temperature: 26ºC, 18.5ºC, 41.4ºC, etc.<br>
While other sensors have a digital behavior, that is to say that there are only two possible values: yes or no. For example, a button, presence sensor, etc.<br>
In our laboratory we have the following sensors:
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<th>Sensor</th>
<th>Type</th>
<th>Fuction</th>
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<td>ADXL 343B</td>
<td>Analogic</td>
<td>Accelerometer</td>
</tr>
<tr>
<td>Microphone 22dB</td>
<td>Analogic</td></td>
<td>Microphone</td>
</tr>
<tr>
<td>LDR</td>
<td>Analogic</td></td>
<td>Photoresistor</td>
</tr>
<tr>
<td>Button</td>
<td>Digital</td>
<td>Button</td>
</tr>
<tr>
<td>Potentiometer</td>
<td>Analogic</td>
<td>Variable resistor</td>
</tr>
<tr>
<td>Lm35</td>
<td>Analogic</td>
<td>Temperature sensor</td>
</tr>
<tr>
<td>Thermistor 10k</td>
<td>Analogic</td>
<td>Temperature sensor</td>
</tr>
<tr>
<td>Hall Sensor</td>
<td>Analogic</td>
<td>Measure magnetic field</td>
</tr>
<tr>
<td>RTD</td>
<td>Analogic</td>
<td>Temperature sensor</td>
</tr>
</tbody>
</table>
</div>
In my case I use the thermistor 10Kohm and the HCSR04: Ultrasonic Sensor. The first one is analogic temperature sensor and the last one is a digital Sensor which serves to measure distance of an object with respect to the sensor.
<a title="Sensors"><img class="image center" src="images/week11/sensors.jpg"></a>
The operation of the thermistor is quite basic, when the resistance is in contact, it will raise its temperature according to the following graph.
<a title="Output Curve"><img class="image center" src="images/week11/outputcurve.jpg"></a>
<h6>Source: http://www.bapihvac.com/wp-content/uploads/2010/11/Thermistor_100K.pdf</h6>
The operation of the ultrasonic sensor is different, the transmitter (trig pin) sends a signal: a high-frequency sound, when the signal finds an object, it is reflected and the transmitter (echo pin) receives it. The time it takes for the signal to arrive is what indicates the distance of the object.
<a title="HCR 04 function"><<img class="image center" src="images/week11/hcr04function.jpg"></a>
<h6>Source: https://randomnerdtutorials.com/complete-guide-for-ultrasonic-sensor-hc-sr04/</h6>
The choice of these sensors are aligned with my final project, since I have to measure the water temperature of the steaming machine and the amount of water that exists in the tank with the presence sensor.
<h2>Board</h2>
Working.
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For this week, I made a replicated the head of Bender, from Futurama series by Matt Groening, because it is necessarily made a 3d design with some curves.
<a title="Bender"><img class="image center" src="images/week10/bender.jpg"></a>
I use inventor software to make the half of the head of Bender with some special’s designs tools like revolution, trim, cut and planes.
First of all, I draw 2d sketch of the head and the antenna and make a revolution of the sketch.
<a title="Head"><img class="image center" src="images/week10/revolution.jpg"></a>
For the following steps, it is very important to use different planes in our design, one of them will be tangent to the curvature and parallel to the lower face to be able to draw the eyes.
<a title="Plane"><img class="image center" src="images/week10/plane.jpg"></a>
Once the plane is created, an internal extrusion of the eye cavity is made.
<a title="Eyes"><img class="image center" src="images/week10/eyes.jpg"></a>
To draw the eyes, a 2d drawing is made with another plane and then a revolution. The mirror tool is used for the other eye.
<a title="Revolution eyes"><img class="image center" src="images/week10/rev2.jpg"></a>
To draw the mouth, first make a cut using another additional plane and make a small cut.
<a title="Mouth"><img class="image center" src="images/week10/mouth.jpg"></a>
Adding some details in the mouth, we have the final design.
<a title="Bender Final design"><img class="image center" src="images/week10/final.JPG"></a>
<h2>3D Machining</h2>
<h3>Material</h3>
To create the positive of the mold, a block of blue machinable wax with the dimensions of 77 mm x 160 mm will be use.
<a title="WAX"><img class="image center" src="images/week10/wax.jpg"></a>
This material is not a hazardous substance or mixture, you can read more about safety data sheet<a hred="http://www.freemanwax.com/pdfs/sdsFerrisBlueMachinable.pdf"> here</a>
<h3>Machining</h3>
We use the Roland mdx-540 machine with the SRP Player software to perform the positive machining of the mold. The first step is to indicate the measurements that our design will have, in my case is this size:
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<table class="alt">
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<td>X</td>
<td>30mm</td>
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<td>Y</td>
<td>67.5mm</td>
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<td>Z</td>
<td>15mm</td>
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</tbody>
</table>
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<a title="Size"><img class="image center" src="images/week10/size.jpg"></a>
For type of milling we use better surface finish, model with many curved surfaces and cut only top.
<a title="Type of milling"><img class="image center" src="images/week10/type.jpg"></a>
Now we choose material (polycarbonate) and create the measure with a small offset of the real size, that is necessary for casting, for material is not lost or incessant elements are manufactured
<div class="table-wrapper">
<table class="alt">
<tbody>
<tr>
<td>X</td>
<td>55mm</td>
</tr>
<tr>
<td>Y</td>
<td>82mm</td>
</tr>
<tr>
<td>Z</td>
<td>36mm</td>
</tr>
</tbody>
</table>
</div>
<a title="Type of milling"><img class="image center" src="images/week10/type.jpg"></a>
For roushing we use these parameters
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<table class="alt">
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<td>Margin</td>
<td>5mm in all faces</td>
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<td>Tool</td>
<td>4mm flat endmill</td>
</tr>
<tr>
<td>Feed rate</td>
<td>1000mm</td>
</tr>
<tr>
<td>Spindle</td>
<td>9000 RPM</td>
</tr>
<tr>
<td>Cutting-in amount</td>
<td>0.27mm</td>
</tr>
<tr>
<td>Path interval</td>
<td>1 mm</td>
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<tr>
<td>Finish margin</td>
<td>0.2 mm</td>
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</tbody>
</table>
</div>
<a title="Roushing process"><img class="image center" src="images/week10/roushing.jpg"></a>
For the finishing we use these parameters:
<div class="table-wrapper">
<table class="alt">
<tbody>
<tr>
<td>Margin</td>
<td>3.2mm in all faces</td>
</tr>
<tr>
<td>Tool</td>
<td>3mm ball endmill</td>
</tr>
<tr>
<td>Feed rate</td>
<td>800mm</td>
</tr>
<tr>
<td>Spindle</td>
<td>9000 RPM</td>
</tr>
<tr>
<td>Cutting-in amount</td>
<td>0.1 mm</td>
</tr>
<tr>
<td>Path interval</td>
<td>0.1 mm</td>
</tr>
<tr>
<td>Finish margin</td>
<td>0 mm</td>
</tr>
</tbody>
</table>
</div>
<a title="Finishing process"><img class="image center" src="images/week10/finishing.jpg"></a>
In the preview we can see that the estimated cutting time will be of 3,9 hours. Do not forget change of endmill in the process
<a title="Cutting process"><img class="image center" src="images/week10/cutting.jpg"></a>
Like the fabrication of all boards, we define zero position, but in this case will be in the middle of the wax, because the center o the software is in the middle of the design
<a title="Zero"><img class="image center" src="images/week10/zero.jpg"></a>
During the cutting process, we use a vacuum cleaner to remove all unnecessary material
<a title="Vaccum"><img class="image center" src="images/week10/vacum.jpg"></a>
We can appreciate a small video of the design cutting process.
<iframe width="560" height="315" src="https://www.youtube.com/embed/X_qVr9fDPcM" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
<h2>Moulding</h2>
After the machinig, it is time to create the moulding, in my case I use 3 materials, all of them are foodfriendly, that means we can also make food.<br>
<br><h3>Materials</h3>
The main material that I used in the laboratory is silicone rubber, it is very important to know the safety and hygiene precautions of this type of products, as seen in the picture
<a title="Safety"><img class="image center" src="images/week10/safety.jpg"></a>
You can find more information about the safety data sheet<a href="http://www1.mscdirect.com/MSDS/MSDS00026/48460802-20180217.PDF"> here</a>
The silicone rubbers from the laboratory are the following:
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<thead>
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<td>Name</td>
<td>Picture</td>
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<td>Silicon Rubber RTV</td>
<td><a title="Silicon Rubber RTV"><img class="image center" src="images/week10/rtv.jpg"></a></td>
</tr>
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<td>Silicon Rubber Platinum L-20</td>
<td><a title="Silicon Rubber Platinum L-20"><img class="image center" src="images/week10/sikalist.jpg"></a></td>
</tr>
<tr>
<td>Silicon bi-component Platinum Gel 1510</td>
<td><a title="Silicon bi-component Platinum Gel 1510"><img class="image center" src="images/week10/bicomponent.jpg"></a></td>
</tr>
</tbody>
</table>
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Only one catalyst will be needed for the first mold, for the others they are not necessary.
<a title="Materials"><img class="image center" src="images/week10/materials.jpg"></a>
For this case, 100 g of silicone rubber and 10 drops of catalyst are used to make the mixture, then stir the mixture well until it has a uniform product, after that it is poured into the positive of the mold and stirred slightly to eliminate all types of bubbles
<a title="Process of moulding"><img class="image center" src="images/week10/process.jpg"></a>
The process is similar for all materials, in case the catalyst is not used, the mixture is half of compound A and half of compound B.
Here is the result of the moulding.
<a title="Moulding"><img class="image center" src="images/week10/moulding.jpg"></a><br>
<br><h2>Casting</h2>
For the casting process, I use a crystal resin polyester with UV protection with a catalyst.
<a title="Casting Material"><img class="image center" src="images/week10/cristal.jpg"></a>
From the safety data sheet, I read Avoid inhaling vapours. Wear protective equipment. Gloves ‐ Goggles ‐ Boots. Wear self‐ contained breathing apparatus. It is Flammable and the mixture of product vapour and air could be explosive. You can read more<a href="https://www.easycomposites.co.uk/downloads/MSDS/EC-MSDS-Water-Clear-Polyester-Casting-Resin.pdf"> here.</a><br>
Using the necessary protections to avoid intoxications, we proceed to make the mixture of the resin with the catalyst with the proportion of 5 drops every 100g.
<a title="Casting process"><img class="image center" src="images/week10/casting.jpg"></a>
In the negative of the mold I put some electronic components so that it has a better appearance, the result being the following.
<a title="Bender electronic"><img class="image center" src="images/week10/bendertronic.jpg"></a>
I also made mixtures with other resins and using metal and wood shavings.
With other molds I perform the casting with chocolate, as shown in the picture.
<a title="Chocolate"><img class="image center" src="images/week10/chocolate.jpg"></a>
<h2>Hero shot</h2>
And Here are all my moulding and casting
<a title="Hero shot"><img class="image center" src="images/week10/hero.jpg"></a>
Sorry, I ate the chocolate, it was delicious!
<h2>Group assignment</h2>
For the group assignment, we have made several tests with different types of resin, in my case I made polyester resin.<br>
The difference of the previous processes, the design, a box was printed and the resin of the negative of the mold was emptied inside, as seen in the picture.
<a title="Moulding"><img class="image center" src="images/week10/grupalmoulding.jpg"></a>
The same steps are carried out and we have the following:
<a title="Casting"><img class="image center" src="images/week10/grupalcasting.jpg"></a>
The result.
<a title="Result"><img class="image center" src="images/week10/grupalresult.jpg"></a>
To see all the documentation of the group work, you can visit the <a href="http://fabacademy.org/2019/labs/cit/">CIT page.</a>
<h2>Problems and solutions</h2>
It is very important to keep in mind that we can not delay a lot of time mixing the materials of casting and molding, but these materials harden and we will not be able to work.<br>
Another important factor is to have patience so that the molds are dry enough to be able to remove them and avoid what you see in the picture.
<a title="Fail"><img class="image center" src="images/week10/mouldingfail.jpg"></a>
With this week you can see the importance of being able to make several copies of designs made in a design software without having to wait long in print.
<p>
<h2>Download files</h2>
You can donwload files Here: <br>
Desing<br>
<a href="images/week10/bender.ipt" download>Bender (Inventor 2018)</a><br>
Roughing<br>
<a href="images/week10/Roughing1.prn" download>Roughing (Modela MDX-540)</a><br>
Finishin<br>
<a href="images/week10/Finishing1.prn" download>Finishing (Modela MDX-540)</a><br>
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