WELCOME TO ONSHAPE!

This exercise shows how to assemble a Water Molecule.

If you could break a drop of water into tiny pieces, the smallest piece (that is still water) is a water molecule.

Water is one of the simplest molecules - composed of one Oxygen (O) atom and two Hydrogen (H) atoms. Because of the electrical forces involved, the angle between the H-O-H atoms is approximately 104.5 degrees.

This exercise shows how to assemble atoms and bonds together to make a Water (H2O) molecule.

Use the arrow navigation buttons below to follow through these instructions as you work.

Most of the pages of this tutorial contain a video to illustrate the steps and help you succeed.

CREATE AN ACCOUNT

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Click the New Tab icon in the top-right corner to open this tutorial in a new tab in your browser.

If you haven't already, create an Onshape account here.

Once you've signed in, return to the guide and continue to the next page.

COPY THIS DOCUMENT

To edit the Water Molecule document, you need to make your own copy of the public, read-only document.

Steps

1. Click the Onshape logo at the top-left hand corner of the window. This will return you to your Onshape dashboard.
2. To the left, click on the Public filters to view all public documents.
3. Search for the document name "Molecule Assembly Exercise" in the top advanced search bar.
4. Right-click the Onshape: Molecule Assembly Exercise document, and choose Copy workspace...
5. Change the name of your document - for example, add your initials at the end.
6. The workspace will open.
7. Click the arrow at the bottom right of this page to continue.

Note:

The Public documents are a great resource for finding ideas, best practices and examples of how to model and design in CAD. Spend a few minutes exploring!

Investigate Oxygen

The key to understanding Onshape Assemblies is to understand Mate Connectors. Can you find the mate connectors on the Oxygen atom?

Steps

1. If you can't see the Tabs column on the left, click the Toggle tab manager icon in the bottom-left corner of the window to show the Tab list.
2. If it isn't already open, double-click the Oxygen Atom Part Studio to open it.
3. Right-click in the white space next to the Oxygen atom and rotate it around. Notice that there are two holes where the bonds can attach, and in each hole, a Mate Connector appears.
4. Mate connectors are used to position parts and surfaces in assembly mates. In other words, they are used to align and two different parts
5. They can be added to a part (as in this case) or created on the fly during the assembly process.

Add a Mate Connector

This will allow use to more easily assemble the water molecule.

Steps

1. Double-click the Hydrogen Atom Part Studio to open it.
2. Right-click in the white space next to the atom and rotate it around so that you can see the open end of the bond hole. Notice that there is no Mate Connector here.
3. To add one, drop down the features menu and choose the Mate Connector icon
4. With the Mate connector dialog open, move the cursor over the open end of the hole.
5. As you move the mouse, notice that the cursor 'wakes up' default inference points, and the inference point closest to the cursor highlights as a Mate connector. As you continue to mouse over the entity, different default inference points appear.
6. Keep moving the mouse around until you are able to highlight the mate connector that is tangent with the sphere surface, and then double-click it to place it.
7. Select the green check mark to complete the sketch.

Tip:

If you made a mistake, click Undo at the top to try again.

Create a New Assembly

Assemblies are workspaces used to put the parts and sub-assemblies together.

Steps

1. Click the Home tab to minimize any open folders.
2. Click the Insert New Element tab at the bottom of the page, and choose Create Assembly from the pop-up menu.
3. Right-click the new "Assembly 1" tab you just created to rename the Assembly to "My Water Molecule".

Insert Oxygen and Fix

To start, we'll add the oxygen molecule to the assembly.

Steps

1. Click Insert to browse for the oxygen, and choose the Oxygen atom from the list
2. If you hover the mouse over the workspace, you can choose a location to place the part.
3. Alterantively, by simply clicking the green check , the part will be placed with it's origin coincident with the assembly origin -- do that in this case.
4. To fix the Atom so that it doesn't spin, right-click it and choose Fix

Assemble the Bonds

Real atomic bonds are pure energy, but for this assembly they are modeled as translucent cylinders.

Steps

1. Similar to the way you inserted the Oxygen atom, click Insert to browse to the bond part.
2. Insert the bond twice, and click somewhere near the Oxygen atom to place them. Don't worry about exactly where they go yet.
3. Select the green check mark to close the Insert dialogue.
4. Choose Fastened Mate and click on the Mate Connector at the surface of one of the bond holes.
5. Notice that the Fastened dialogue shows that feature in the Mate Connectors list.
6. Click on the Mate Connector at the end of one of the bonds. The bond will immediately move and the two mate connectors will align.
7. It may be neccessary to click the Flip primary axis button to flip the bond with respect to the atom.
8. Click the green check mark when it looks right.
9. Repeat these steps for the other bond.
10. Click the red X to finish fastening mates.

Assemble Hydrogen

This step is similar to the last one, except this time you'll assembly the Hydrogen atoms.

Steps

1. In the same way you assembled the bonds, click Insert to browse to the Hydrogen part.
2. Insert Hydrogen twice, and click somewhere in the white space to place them. Don't worry about exactly where they go yet.
3. Select the green check mark to close the Insert dialogue.
4. Choose Fastened Mate again, and click on the Mate Connector at the end of one of the bonds.
5. Click on the Mate Connector at the surface of the Hydrogen bond hole. The Hydrogen will immediately move and the two mate connectors will align.
6. It may be neccessary to click the Flip primary axis button to flip the bond with respect to the atom.
7. Click the green check mark when it looks right.
8. Repeat these steps for the other Hydrogen.
9. Click the red X to finish fastening mates.

Food for thought...

Steps

1. When you added the bonds why did they move to align with the Oxygen atom, while the Oxygen atom stayed in place?
2. Hint: go back and review the Insert Oxygen step.
3. If you wanted to model a more complex modecule, what might you have to do?
4. Hint: look at how the oxygen atom was modeled. How were the holes made?

Mission Complete

Congratulations on assembling the water molecule!

We hope you found this short exercise fun and useful. For more learning resources, please visit the Onshape Learning Center.

To send feedback, or for help and questions, visit the Onshape Forum.