Assignment 4: Make A Molecule

Introduction

Using a free, open source molecule editor like Avogadro you can construct your own molecular models, solve for low-energy configurations, and read out the bond lengths and bond angles. But for this assignment we've done all that work for you. All length values given in "inches" below are really in picometers.

In this assignment you will construct an ethanol molecule in SolidWorks that is hollow inside and has a removable cap. You will then 3D print the molecule and the cap.

Making the Cap

Start a new part.
Create an extruded base on the Top Plane
Draw a circle centered on the origin with diameter 2.35 inches.
Set the extrude depth to 0.5 inches.
This creates a disk.

Create a Revolved Base feature on the Right Plane.
Draw a horizontal line along the top edge of the disk, starting at
  the midpoint (directly above the origin) and running leftward to just
  past the edge of the disk.
Dimension the horizontal line to 1.2 inches.
Draw a vertical line upward from the top edge of the disk, rising from the midpoint.
Add an Equal relation between the two lines.
Draw a centerpoint arc connecting the ends of the two lines.  This
  gives you a quarter circle.
Check the last endpoint of the arc with Select Other and merge it with 
  the line endpoint if necessary:
     Click on the arc endpoint.
     Click on Add Relation.
     Right Click on the arc endpoint and choose Select Other.
     From the pop-up menu, choose the other point.
     Click on Merge in the properties tab.
Exit the sketch and use a 360 degree revolve of the quarter circle around
  the vertical line to form a hemisphere.

Click on the flat bottom of the cap to select it.
Use the Shell feature to hollow out the cap; set the
  shall thickness to 0.2 inches.

Save your part as Cap.SLDPRT
Then do "Save As" and set the file type to STL.
Click on the Options button and select Fine triangulation.
Save the file as Cap.STL.

Making the Molecule

Create a new part.

FIRST CARBON:
Create a Revolved Base Feature, sketching on the Top Plane.
Draw a vertical line extending THROUGH the origin and dimension it to length 3.4 inches.
Select the line's midpoint and make it coincident with the origin.
Use the centerpoint arc tool to draw a left semicircle bounded by the line endpoints.
Check the last endpoint of the arc with Select Other and merge it with 
  the line endpoint if necessary:
     Click on the arc endpoint.
     Click on Add Relation.
     Right Click on the arc endpoint and choose Select Other.
     From the pop-up menu, choose the other point.
     Click on Merge in the properties tab.
Exit the sketch and use a 360 degree revolve of the semicircle around the
  vertical line to form a sphere.
In the Feature Manager Tree, rename the feature Carbon1.
Color the entire sphere (the Carbon1 element in the Appearances pop-up list) pale green.

SECOND CARBON:
Create a new sketch on the Front Plane.
Draw a vertical construction line upward from the origin and dimension it to 1.54 inches.
Exit the sketch.
In the Feature Manager Tree, rename the sketch to Backbone1.
Create a Linear Pattern feature and set the vertical line of Backbone1 as Direction 1.
Set the distance D1 to 1.54 inches.
Set the # of instances to 2.
Set the Reolve feature as the Features to Pattern (just click on the sphere to select it).
If the Reverse direction button (to the left of the Direction 1 box) is
  selected, click it to deselect. We want the yellow outline of the new
   carbon being constructed by the linear pattern to be on the same side
   as the dashed Backbone line.  (If you don't see a yellow outline, click
   on "Full Preview" in the linear pattern dialog box on the left.)
Click OK.
Rename the feature Carbon2.

FIRST HYDROGEN:
Create a new Revolved Base on the Front Plane.
Draw a diagonal construction line from the origin downward and to the left.
Dimension the line length to 1.1 inches.
Dimension the angle between the line and the vertical Backbone line from
   the previous sketch to 109 degrees.
Draw a new vertical line centered on the left endpoint of the line you just drew.
Add a relation to enforce the midpoint property.
Dimension the line to length 2.4 inches.
Use the centerpoint arc tool to draw a semicircle to the left of and bounded
  by the vertical line.  Merge the second endpoint.
Exit the sketch and use a 360 degree revolve of the semicircle to form a sphere.
In the Feature Manager Tree, rename the Reolved Base feature to Hydrogen1.
Color the sphere (Hydrogen1 in the Appearances pop-up list) white.

SECOND AND THIRD HYRDROGENS:
Create a Circular Pattern feature (in the pulldown menu from Linear Pattern).
For the axis/surface of rotation parameter (first parameter box), select Backbone1.
For the # of instances, select 3.
Check the Equal Spacing box.
For the Features to Pattern, select Hydrodgen1.
Click OK to complete the feature.

OXYGEN:
Make a new Revolved Base on the Front Plane.
Draw a diagonal construction line from the top end of the Backbone line up and to the right,
  and dimension it to length 1.43 inches.
Set the angle between the vertical and diagonal construction lines to 120 degrees.
Draw a solid horizontal line centered on the endpoint of the diagonal construction line,
  and dimension is to length 3.04 inches.
Select the midpoint and add a relation to enforce this property.
Use the centerpoint arc tool to draw a semicircle above the horizontal line.
  Merge the second endpoint.
Exit the sketch and use a 360 degree revolve of the semicircle to form a sphere.
Rename the feature to Oxygen1.
Color Oxygen1 red.

FOURTH HYDROGEN:
Go the Features Tab, and in Reference Geometry, create a Plane.
Set the first reference to Top Plane
Set the second reference coincident to the top point of your Backbone line and click OK.
Rename the plane Carbon2Plane.
Create a new Revolved Base feature on Carbon2Plane.
Draw a horizontal construction line from the origin to the left.
Draw a diagonal construction line from the origin up and to the left, and
  dimension it to 1.1 inches.
Set the angle between the two construction lines to 70 degrees.
Draw a horizontal line with its midpoint being the top point of the diagonal construction line.
Add a relation to enforce the midpoint constraint.
Dimension the horizontal line to length 2.4 inches.
Use the centerpoint arc tool to draw a semicircle above and bounded by the horizontal line.
  Merge the second endpoint.
Exit the sketch and use a 360 degree revolve of the semicircle to form a sphere.
Rename the feature Hydrogen4.
Color Hydrogen4 white.

FIFTH HYDROGEN
Create a mirror feature.
Set the mirror face/plane to the Front Plane.
Select Hydrogen4 as the feature to mirror.
Click OK to complete the mirror.

SIXTH HYDROGEN
Create a Revolved base on the Front Plane.
In the Feature Manager Tree, expand the Oxygen1 feature to reveal its sketch.
Right click on the sketch and click "Show" (the eyeglasses icon) to make it visible.
Add a new construction line from the end of the oxygen diagonal line, running
  almost vertically but slightly to the right.
Dimension this construction line to 0.94 inches and set the angle between it
  and the diagonal below the horizontal line to 125 degree.
Draw a horizontal line centered on the new construction line, and
  dimension is to length 2.4 inches.
Use the centerpoint arc tool to draw a semicircle above the horizontal line.
  Merge the second endpoint.
Exit the sketch and use a 360 degree revolve of the semicircle to form a sphere.
Rename the feature Hydrogen6.
Color the sphere white.

CAP OPENING:
Create a Revolved Cut feature.
Instead of selecting a surface for a new sketch, open the feature tree and
  select the sketch from the Hydrogen6 feature.
To select the Axis of Revolution, click on the horizontal line in the Hyrdogen6 sketch.
Click OK to complete the cut.  This removes the Hydrogen6 sphere, leaveing a depression
  in the Oxygen1 sphere.

SHELL:
Click on the depression in the Oxygen1 sphere.
Create a Shell feature.
Set the shell thickness to 0.2 inches.
Click OK to complete the shell.

BASE: Add an extruded base of your own design to the bottom of the
molecule that can act as a stand.  See the figure below.  We used
three thin lines in our design, but you are free to innovate.  Add your
initials or some other unique feature to distinguish your molecule
from others.

Save your part as Ethanol.SLDPRT
Then save it again as Ethanol.STL.
During the save dialog, click on the Options button and select Fine triangulation.

Printing Your Parts

What to Hand In

• Bring your molecule to class to show off.
• Post a picture of it on Piazza, in the thread provided.
• Hand in your SolidWorks parts files via Autolab.
• Files and plastic due by Monday, November 17.

Last modified: Tue Dec 2 05:26:39 EST 2014