This was the wood block and tackle we designed and built for a kinetics assignment. We planned it out so each person would have their own to keep. The main axle is 1” thick dowel. Then around it are 1/4” dowel chunks that act as rollers between the axle and the pulley sheave.

In hindsight, there was no roller carrier so the rollers clash into each other internally and actually create a lot of friction. So it rolls but not with that smooth spin I was hoping for. If I wanted to science I could set up a motor and belt on it and run it with a timer and see how it does over time. I know it will fail, I just don’t know when.

The hardest part was getting the rollers loaded onto the sheave. That’s because there was a lip on the sheave to act as a bearing race. To solve that I built a special tool dowel, It had a special slot drilled into it that could be used to feed the rollers into the sheave. Then the whole system can be slid off the tool and onto the axle dowel.

The walls and spacers are attached with 4 registration pins. Each end has spacers that are made thin enough that the rope can run past them.

Also included a loading hole on top and bottom, that way they could be used with multiple blocks together.

A better version with the power of hindsight would use carrier rings made out of thin ply. Then on each of the roller dowels, use a lathe to add shoulders on each side and part it off at the right length. Then it will have a [short narrow |normal dowel long | short narrow] that can ride in the carrier. It would make a roller cage that keeps each roller separated and might be able to do that free spin.