This is a hex head bolt:
Many yo-yos, especially those older ones, use this type of axle. The Freehand Zero and almost all plastic Duncan yo-yos, the One Drop Project, and others all use this type of axle.
To tune a yo-yo with a hex bolt axle all you need to do is this:
Take off the cap on the bolt side
Then, throw the yo-yo and gently touch your finger to it. How much does it vibe after this?
Take the yo-yo apart being careful to not let the bolt come out of its seat.
Notice how these hexagons line up. Imagine the inner red hexagon to be the bolt head and the outer blue hexagon to be the place it sits in the yo-yo.
- What you want to do is rotate the bolt one notch clockwise. When you do that the faces of the two hexagons will line up like this:
Does that make sense? Yes? Good.
- Screw the yo-yo together.
Repeat steps 2-6 until the yo-yo gets smoother. You will notice there is a point where the yo-yo is pretty smooth then you rotate the bolt one more time and it is less smooth. Stop, and rotate the bolt back to where it was before. That is the smoothest point.