13 of 24 - Dowty Rotol

The realities of modern capitalism caught up with Holman’s in 1980, and the Camborne site was scheduled for closure. Some of us were offered work in an aircraft factory in Gloucester, so rather than stay in Cornwall and scramble for work, we accepted the offer, packed our bags, and headed for the M5.

Dowty Rotol—a name that carried weight in aerospace circles—was known for its precision engineering, especially in propellers and hydraulic systems. Their components flew on aircraft used by the Royal Family, which lent a certain hush to the shop floor, as if the parts themselves demanded decorum.

I was on permanent nights, inspecting components as they came off the machines. The rhythm was steady: the machinists would produce their first-offs, and I’d measure every critical dimension against the drawings. No shortcuts. No assumptions. Just the quiet click of micrometers and the glow of the optical comparator. If the first-off was correct I would stamp the machinists work card which was his go ahead to produce the whole batch. I would inspect periodically to ensure that accuracy was maintained.

My inspection bay contained an array of tools:

An Optical Comparator: For thread profiles and contours too fine for tactile instruments. The silhouette of a part projected onto the screen—magnified, ghostly, and unforgiving. You could see a burr like a mountain range.

Cerrobend: A fusible alloy, with a very low melting point, used to cast internal geometries. It melted at 70°C and solidified quickly. We’d pour it into cavities to inspect internal threads or bore shapes. The solidified lump, bearing a perfect impression of the internal feature could be removed and examined and measured.

Dial Test Indicators: Very sensitive instruments but robust enough to be used in a machine shop, used to detect runout or flatness. The stylus would sweep across a surface, and the needle would twitch—sometimes just enough to make you call over the machinist.

Sine Bars and Angle Blocks: For setting up or verifying angles with trigonometric precision. A stack of slip gauges beneath one roller, and you had a triangle truer than any drawing.

Slip Gauges: Steel blocks wrung together with a twist and a prayer. They clung by molecular attraction, no magnets needed. We built dimensions from them to provide measurement comparison or produce angles with the sine bar.

And Micrometers and Calipers: The old reliables. Calipers for the quick whisper, Micrometers for the final word. You learned to trust the ratchet’s feel, the way it kissed the part before giving you a number.

As the machinists produced the first-offs of the night shift, I’d measure every dimension against the drawing. They were proof the setup was sound. If a bore was out by a thou, or a thread profile showed a burr under the comparator, the whole run paused. First offs were the moment of truth, and my bench was the courtroom.

There was pride in the process. I wasn’t just checking parts—I was holding the line between flight and failure. Each measurement was a kind of oath. However, mistakes still occurred and when they did they tended to be obvious and irreversible.

One of the excellent machinists on my line once misjudged a measurement by 10mm, a chasm in the world of precision engineering. I missed it as well. I was looking for a speck and missed the plank. The micron dimension was spot on, but the millimetre tally was ten off. The result of this was about a dozen very expensive lumps of metal were total scrap.

Explaining why I made this mistake could sound as if I am excusing myself. I am not. I cost the company lots of money, and caused the machinist stress and humiliation. I remember asking him with a conspiratorial wink if the component was correct. Up until this night EVERY first-off he had produced was perfect. So, it was a sort of metaphorical nudge in the ribs, a “I don’t even need to look at this do I?” kind of thing. I assumed that the component would be correct so that is what I saw.

The lesson of course is that familiarity really does breed contempt. In the safety world it is necessary to repeat the same message every day, to hammer the important points home each shift, no matter how many times in the past you have stressed the need to wear PPE you must continue to do so. Every time someone dons a harness the straps must be checked for damage and the fit adjusted to the wearer. Every time before a gas monitor is deployed it must be examined to ensure the battery is full and the detectors are operating correctly. Every time information must be provided and checks and balances employed.

Soon after this expensive mistake I was transferred to a day shift position as a repair inspector on the Queens Flight.

In 1968, the company was awarded the Queen’s Award to Industry for Export Achievement, a prestigious recognition that likely reflected its contributions to elite aviation, possibly including components for the Queen’s Flight aircraft.

The Queen’s Flight didn’t just represent royal transport; it was the pinnacle of precision and discretion, and I was inspecting the literal foundation it rode on. Stripping those undercarriages to individual components revealed the epitome of precision engineering—every bush, bracket, and bore telling its own quiet story of craftsmanship.

The components were brought to my bench in stillages in conjunction with very detailed paperwork. My job was to measure and record the wear patterns and tolerances and identify the necessary rectification required. For some components I could schedule boring out or skimming down to the next acceptable dimension. Other components, such as bores or pistons may have required a fresh layer of chromium and machining back to tolerance. But some were beyond repair or had reached the end of their “life”. These were consigned to the scrap stillage to be destroyed to prevent accidental reuse.  For each of these various destinations my ink stamp was the verdict—repair, reline, or scrap.

John Lennon was shot dead whilst I worked in Dowty Rotol. I went to Liverpool with many others to show my respect.