Wick Oiler

A small cup above the bearing, with a tube leading down to it.

1. Fix a glass jar or a small metal cup to a plywood bracket above the bearing housing.
2. Drill the cup's base for a delivery tube of 6 mm aluminium or brass, and seal the joint.
3. Run the tube down so its lower end sits just above the shaft.
4. Fix the bracket with M5 × 30 socket head cap screws × 2, M5 flat washers × 4 and M5 hex nuts × 2.

Height above the bearing matters less than you would expect. Capillary action lifts oil UP the wick out of the reservoir and gravity does the rest; the feed rate is governed by the wick, not by head. This is why a wick oiler works reliably at almost any reasonable height, unlike a gravity drip which depends on it.

The wick is the metering device, so make several and compare them.

1. Cut three lengths of wool yarn: one strand, three strands twisted, and six strands twisted.
2. Make each long enough to reach from the reservoir's bottom, up over the rim or through the tube, and down to the delivery point.
3. Soak all three fully in oil before use.
4. Label them by strand count.

Why wool rather than cotton or synthetic. Wool's scaled fibre surface holds and transports oil better, and it does not rot in oil the way some natural fibres do. The same property makes wool felt the traditional wiper material — one fibre, two applications, both exploiting capillary behaviour.

Three wicks, one reservoir, a countable result.

1. Fit the single-strand wick, fill the reservoir and let it settle.
2. Count drips per minute at the delivery end over five minutes.
3. Repeat with the three-strand and six-strand wicks.
4. Now warm the oil slightly and repeat the three-strand test.
5. Tabulate strands, temperature and drips per minute.

The classic wick-oiler fault, deliberately provoked.

1. Fit the six-strand wick and let it run.
2. Lower the delivery end well below the reservoir base and watch.
3. If the wick becomes fully saturated end to end, it stops metering and siphons — a continuous flow rather than drips.
4. Raise the delivery end, or thin the wick, until dripping resumes.

Wick lubrication is everywhere in nineteenth and early twentieth century machinery — line shafting, locomotive axleboxes, sewing machines, machine tools. Railway axleboxes used a pad of oil-soaked wool waste pressed against the journal, which is the same principle without a reservoir, and generations of railway maintenance amounted to keeping those pads oiled and clean.

The three feeders in this batch differ in who is in control. The wick feeds continuously and automatically, at a rate nobody sets after installation. The sight-feed drip oiler feeds at a rate the operator dials and can watch. The grease nipple feeds nothing at all until somebody chooses to pump it. Automatic and unsupervised, adjustable and visible, or manual and deliberate — that is a choice about trust and attention, not about lubrication.

Its enduring virtue is that it cannot fail energetically. No pump to seize, no pressure to lose, no control to mis-set. It either feeds or it stops, and it stops gently. For machinery that runs unattended for long periods at modest speeds, that is worth more than precision.

Honest limits: it feeds while the machine is stopped as well as running, wasting oil; it cannot deliver enough for a heavily loaded or fast bearing; the rate drifts as oil thickens with age and cold; and the wick itself is a consumable that hardens and must be renewed. Modern equivalents replace it with a pressurised system precisely because those limits matter more as machines get faster.