I designed and made a pivot of a link using for washing stone. I drilled a hole on the peripherial of a pully and tapped M3 thread. I threw a collar for a pivot on the hole of a link, and clamped a plastic washer and a SUS washer on the both of the link with a M3 screw.
I have a small drilling machine for making less than 6.5mm diameter holes. The working ability is little. So I looked how it drives power. The photo shows its drive. Although the belt is timing type, the pullies are for V belt. The ratio of diameter is 20 : 46.