The definition of a bearing:

A device that supports, guides, and reduces the friction of motion between fixed and moving machine parts.

You might be able to grasp this easily by looking at the picture of the bearing that is above. My right hand is grasping a disk. That disk rotates freely. The thumb of my left hand is touching a smaller ring. That smaller ring doesn't rotate. So, we will connect that larger ring to something and it will rotate.

This bearing is part of a project I have here on the website. It is the Ultimate Periscope Project. You can see that project here .

Now let's make the bearing. This is the mechanism that allows the turret to rotate. It's easy to make and probably a new thing for you. We are going to learn something clever here.

It really isn't difficult - just four parts. And we only have to be a bit cautious about where the glue ends up -so the bearing turns freely.

Glue between the strip and the inside hole is good. But try not to let it spill out too much to the outer part. This is because our next part will rotate here. It is quite ok to flip this assembly over and put lots of glue on the bottom to hold these two pieces together.

Slide part B over that assembly and turn it. It should turn freely. Don't do any gluing to it!

Now you can place the smaller ring (part D) and glue it to the inner strip. Do not glue it to the big ring. Once that small ring is glued in place you should be able to still freely rotate the large ring.

Glue that ring onto one end of the spreader section.

And that's it. You have made a bearing out of cardboard.

But, let me show you one more little thing so you have good clarity.

With the periscope we attach an angled top to that bearing (It is glued just to that larger ring and it will rotate smoothly.