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MAS.863.10 |
![](../images/divider.jpg) |
Masoud Akbarzadeh |
MArch | SMArchs | Computation |
How to Make almost everything |
MIT department of Architecture |
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Home | |
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![](../images/main_08_16.jpg) |
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molding and casting | |
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THe exercise for this wee was to make a mold and cast into that. I decided to make a mold for part of my final project proposal.
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![](../images/main_08_01.jpg) |
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This is the model for the 4 Axis robotic arm which I would like to finish by the end of the semester. For this week I made the model and took the last portion of the arm for manufacturing experience.
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![](../images/main_08_02.jpg) |
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In order to make the assembly of the whole arm feasable, I divided each member into two segments; a male and a female. The male has some tabs which interlocks with the female for assembly process.
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![](../images/main_08_03.jpg) |
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Each member is divided into two segments and each segment would be divided into exterior and interior. |
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Making the mold for a halow mamber is a little bit tricky. in order to design the mold, it is important to seperate the whole exterior surface of the model from the interior. Later there should be a mold for exterior and the one for interior.
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![](../images/main_08_d_0.jpg) |
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![](../images/main_08_04.jpg) |
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The whole surface looked very clean except some parts which were hit by the plastic sheild of the vacume around the mill. Later I had to take off the plastic sheild for cleaner cuts.
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Later I used CNC machine to make the mold for the molds. I used 1/4" end mill (ball end) for Horizontal roughing with 50% step over, and 1/8" end mill (Ball) for the Horizontal Finishing with 10% step over.
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![](../images/main_08_d_1.jpg) |
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![](../images/main_08_05.jpg) |
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Using a large amount of material might fill the some small parts of the mold and change the accuracy of the mold.
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Before pouring the polyurethane into the molds, the surface of the mold should be covered with a thin layer of Geso. You should be very patiant to use very little material for covering.
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![](../images/main_08_06.jpg) |
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The next step is mixing the polyurethane in a separate dish.
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![](../images/main_08_d_3.jpg) |
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![](../images/main_08_07.jpg) |
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1/8" diameter Aluminum bars. |
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In order to think ahead about the casting part, I need to use some ventilation pipes in the mold itself. I use Aluminum rods for this objective.
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![](../images/main_08_d_4.jpg) |
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![](../images/main_08_08.jpg) |
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Th rods are coming out of the liquid. |
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The molds after pouring polyurethane.
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![](../images/main_08_09.jpg) |
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16 hours later the polyurethane cured and flexible
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![](../images/main_08_10.jpg) |
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![](../images/main_08_11.jpg) |
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The process of detaching from the foam and Al. rods
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![](../images/main_08_12.jpg) |
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Two molds for one part on top of eachother
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![](../images/main_08_d_6.jpg) |
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![](../images/main_08_13.jpg) |
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It is better to put two layer of stiff materials around the molds not let the rubber bands to cut the flexible mold |
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Now, it is time to cast the Smooth Cast Plastic into the molds. I used syringe to inject the cast into the molds.
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![](../images/main_08_d_7.jpg) |
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![](../images/main_08_14.jpg) |
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![](../images/main_08_d_8.jpg) |
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![](../images/main_08_15.jpg) |
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Final Step opening the mold and detaching the part from the mold. there are some problems regarding this part. the Male part didn't have a very good tabs to go inside the female. I guess this needs more experience in how to desig the tabs in a more efficient way. (further investigation of course!!)
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All Rights Reserved 2010 |