Telescope Session 2 - Building the base

Hey again! This is Part 1 of the second telescope building session. There will be 3 parts to this session spread over 3 different posts. In this session, we're building the base for the telescope, learning how to solder, and preparing our Raspberry Pi. Lazy susans, molten metal, and star charts galore!

Building the base

Source: Wikipedia

Today's main goal is to build the base for the telescope. When it's finished, the telescope will have two degrees of freedom (ways in which an object can rotate). The first is on the z-axis, around a lazy susan in the base. This is the one we will build today. The second, which I'll get to in a future post, rotates on the y-axis. This second degree of freedom takes the form of a camera tower to sweep the skies above.

The base of the telescope is built almost completely out of 3D printed parts. We will need:

• main base
• lazy susan ring
• 4 M4x20 screws
• 4 M4 washers
• 4 M4 locknuts
• 3 3D printed feet for the base
• 3D printed wheel with metal axle

To allow the telescope to rotate from left to right, we need to use a lazy susan. Eventually, we will install a stepper motor to turn the telescope on the lazy susan so that the camera has full viewing access to all the stars in the sky. 

To start, we'll put the lazy susan into our base. Notice that it has an outer and inner circle, both of which rotate independently. By using the 4 M4x20 screws to fasten the outer circle to the base, we can use the inner circle to rotate our telescope. Line up the outer circle of the lazy susan with 4 holes in the telescope base. Coming from the top, place the 4 screws into the holes and secure underneath the base with washers and locknuts. 

At this point, we can place our 3D printed wheel into the base. It should follow the ridged track inside the base, and will eventually be powered by a stepper motor. We can also screw in the 3 feet that will raise the telescope slightly and stabilize it. There are 3 holes evenly spaced on the base where the feet go.

Adding the rotating platform

Now that we have installed our lazy susan, we can build the rotating platform that the rest of the telescope will sit on. This is the section that will be directly attached to the inner circle of the lazy susan. To do this, we will need:

• 10 wedge-shaped 3D printed pieces
• 1 larger 3D printed wedge
• 5 M4 locknuts
• 4 small 3D printed inserts
• 1 blue 3D printed insert
• 24 3D printed dowels

First, we need to assemble the platform that will be attached to the lazy susan. For this, we will need the wedge-shaped pieces, the inserts, and all the dowels. To secure the platform to the base later, we will need to use screws and locknuts. The locknuts need a place to rest, so we put the black inserts into the space in the top of 4 wedges. Place a locknut into each hexagonal hole in the inserts.

Our last insert is the blue one, which goes in a special place. It will be used later for rotating the telescope, and we need to slot it into a hole on the side of one of our wedges. Choose a wedge with a black insert, place your final locknut in the blue inserts' recess, and be prepared to do a lot of sanding. I ended up getting my insert halfway in and resorting to brute force for the rest of it. When the insert is in place, the hole in the locknut should line up with the hole running through the wedge. 

Now we can assemble the platform. Take the larger wedge and place two dowels into its side; one at the top and one at the bottom. Then snap the wedge with the blue insert onto the dowels. Continue this process until a full circle is completed. Make sure that the wedges with black inserts are placed across from each other, so that they are spread out evenly in the circle. 

Putting it all together

The final step for building our base is to attach the rotating platform onto the lazy susan. We will need:

• 4 M4x20 screws
• our base, with the lazy susan
• circular 3D printed platform

Place the platform on top of the lazy susan, and line up the 4 wedges with inserts with 4 holes on the inner circle of the lazy susan. Make sure that the wheel and axle goes through the large hole in the big platform wedge. Then, coming from the bottom of the base, secure the platform to the lazy susan with 4 screws through the black inserts. Tighten the screws with the locknuts.

Woohoo, we've built the base for our telescope!! In the end, it should look like the photo. The platform should rotate smoothly when pushed, and the axle of our wheel should stick up from the large wedge in the platform. Thanks for reading, and keep and eye out for part 2 of this session!