This is what we will be building.

We will be building this double pendulum with standard 608ZZ Shielded 8x22x7 mm bearings. You can purchase them here if you would like to print and assemble this double pendulum. If you haven't already, you should sign up for an account. You will need an account in order to save your work. You will also need to make sure you are using your Chrome browser. If you don't have Chrome, you can download it here.

Setup

Once again, we are going to edit an existing design as a template so that our database isn't overrun with double pendulums. Find the double pendulum in the database and edit the initial node.  If you don't know how to do this see this introductory tutorial.

Modeling

And now for the fun part.

Delete Current Part

We are going to design this double pendulum from scratch, so ctrl click on the parts in the scene and then click the Delete button to remove them from the scene. Your scene should be empty now:

Set Units

The menu is in the top right corner of the screen, open it and set the units to mm in the global units drop down selector.

Enter Sketch Mode

We will start by sketching the profile of the spinner on the YZ plane. Hover your mouse over the origin and click on the red plane once it appears. That will show the Sketch button. Click on the Sketch button to enter sketch mode:

Draw Construction Profile

First we will make the double pendulum base. Start with a sketch like this. The light blue is the profile we will revolve around the black construction line to create a solid.

Add the necessary vertical and horizontal constraints to square the profile up. If you are unfamiliar with constraining see this tutorial. 

The OD will be 30mm this can be set as a 15mm vertical distance between the outer most point and the origin. 

The base should stick out from the wall about 16mm.

The bearing Id shoulder is 12mm in diameter and should be set 4 mm offset from the base.


The bearing id is 8.1mm we can just make the od a line to line fit, this will give us a slight press fit without hardware, add a 4.05mm vertical constraint for the radius. The bearing id is 7mm long so make the axle surface 7mm long also.
 

Finally we need a thru hole for a screw to attach the base to a surface.  Set the ID to 5 mm. 

Revolve Base Profile

Close the sketch ctrl select the profile and the axis and revolve 360 degrees.

Making the first pendulum arm

Click on the large face of the base and start sketching the arm.

Snap the arc center to the origin, set the lines vertical, and set the bottom arc center vertical with the origin.

Then set the lines equal to each other, the arcs equal to each other, and the top vertices of the lines horizontal.

Set the arc radi to 17mm and arm width to 20mm.  Now you can set the center to center distance of the arm to whatever length you would like.  I am going to set this inner pendulum arm to 120mm. 

Finally we need to add the circles for the id bearing thru holes and sockets. The  bearings are 21.95mm in diameter so an even 11mm radius should give us a nice press fit. I am going to set the thru hole circle to 8mm radius. The circles on the other side of the arm can be set equal to circles just created.

The sketch is now done and should contain 5 closed profiles. Close the sketch. 

Moving Sketches 

Since I created the sketch on the face of the base feature I am going to move the sketch 2 mm out before I start extruding the pieces of the arm.

Extrude Arm Profiles

Ctrl select both inner diameter circles and extrude them 30mm since they will cut thru the arm.

Toggle the sketch visibility back on. 

Then extrude the the bearing socekt circles 20mm.

finally extrude the arm 11mm.

Since I want the bearing shoulder to be on the inside face I am going to move both larger cylinder 2mm in y direction.

Double click to select the arm shape first then ctrl double click and select the rest of the arm pieces and cut them.

To make the second arm open the sketch modify the center to center distance to clear the pendulum base, I am setting it to 80mm and repeat the arm creation steps just followed. Then translate the arm in this case -120mm in the z and -13mm in the y direction to statically position the second pendulum arm.

Now you can add some fillets and chamfers to style your pendulum arms if you would like. Depending on the printer capabilities you may need to add a c-clip grove in the bearing sockets if the press fit isn't sufficient to hold the bearings in.

Saving

Congratulations, you just designed a double pendulum! I will be making some snap connectors for the bearing or alternatively you could connect them with nuts, bolts, and washers. 

Now it is time to publish your design. Click on the tree icon at the top right of the interface to load the save form. Label your design and be sure to name your new parts in the parts tab of the save menu.

You will know the save completed successfully when you see this message appear at the bottom of the screen after you click the save button: 

Printing

If you would like to get a physical copy of the double pendulum pieces you just designed, just hit the back button to navigate back to the Design page. Browse through the design tree until you find the node you just saved. Then you have two options:

  • Download and 3D print Yourself: If you have a 3D printer, you can download the STL and print manually. Just click the Download button on the Design page. When your STL has been generated, you will be able to download it:
  • Order a 3D print: If you do not have a 3D printer, you can order a copy of this design by clicking the Buy button. This will upload the design to our fabrication service provider where you can browse through a list of fabricators in your area who will print (and ship if you would like) your design. 

Ready to give this a shot?

Try it yourself

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