Entry 8 – Middle Bi-pulley Support

The middle bi-pulley performs a duel function: It guides the rope that leads to the end pulley; and it offers mechanical support to another rope that actively suspends the purging assembly.

This pulley, I proffer, can be made using two rotating bearing from the innards of a modern ‘hard disk drive’. There are numerous cases in which hard disk drives of the past 10 years, have failed and are discarded (indeed the discarded ‘computer’, may provide a rich source of materials for all manner of projects, some are detailed here). Again see enclosed reality imaging uploads for this process.

Starting with the old hard disk drive unit. In the centre, the spindle motor, is the device that spins the hard disk’s rotating platters (these have been removed here). It can also be used as a finely made set of roller bearings. removing the three screws releases the spindle motor mount.

The read/write heads are supported by this arm, which can be removed. We can use it to provide a fixing point for the bearing. It contains a bearing, that allows the arm to move the heads across the spinning platters. For us, it can be used to support one end of the pulley. The chip provides ambient excitement to users of the AEAPD.

Being a follower of Budo, namely aikido, and aikijo, I have a few jo staff, that are cracked in the middle, and no longer safe to use. This one is was once one of my favourites: made from Quercus mongolica (or Japanese Red Oak) it served me well and will now live again as part of the AEAP Device. To make a square cut with a hand saw on cylindrical objects, wrap masking tape (the wider the better) round once, so that the ends line up exactly. This line can be followed with a hand saw with excellent results.

One end is shallowly drilled to accept the face of the hard disk’s spindle motor.

Spindle motor fits comfortably.

The new axil rotates nicely about its end bearings, The arm bearing is easily fixed with a long screw, but the ‘spindle motor bearing’ needs an attachment method…

Held firmly in a vice the spindle motor is prepared for drilling with a centre punch. We want to drill holes that will run perpendicular, and intersect the threaded holes already in the face.

First hole drilled, joining existing threaded hole.

Before continuing further, a base-plate and side mount were considered and marked up. These are, of course, pieces of the eucalyptus. I will saw notches in line with the pencil marks.

Inductors like this can be found readily enough, almost every discarded appliance will have one or more. I take some of the magnet wire from it to use as an interesting fixing method. This wire is useful because it is already resin coated and will not easily corrode.

Small hooks are formed with snipe-nosed pliers and manoeuvred into the freshly drilled holes.

We are left with an intriguing metal sea creature.

A rubber band can be used to hold the ‘legs’ in place for gluing.

One of the aluminium platter spacers was persuaded with gentle taps of a hammer, onto the new bearing axle. It is then drilled to accept the wire ‘legs’. In retrospect, drilling before ‘persuading’ would be more expedient.

A two part epoxy glue is mixed ready (looks appetising doesn’t it?).

Ready for glue up. The lock-ring, which was a very tight fit anyway, is secured with some ‘super’ variety adhesive.

Legs are carefully threaded through and join is made.

Gentle pressure is maintained overnight with a clamp while the epoxy sets.

The remaining wire is threaded sideways, weaving over its first neighbour and tucked out the way under the next.

The bearings and axil are fastened to the side by a clamp formed of two bolts and a flattened scrap of 15mm copper pipe.

Side is attached to the base with wood glue and a single screw. Clamp is operationalized and we wait for the woodglue to set – a few hours is usually adequate, if the joining surfaces were smooth. Overnight is best.

Almost ready for final finishing… Here it rests upon the hard disk platters (I could not find practical application for them in this instance, despite their reflective brilliance).