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The fitting of Heidenhain digital readouts (DRO) to a manual lathe and manual horizontal borer has aided in the restoration of the Flying Scotsman locomotive.

Dan Holmes, a skilled machinist and fitter, is a key member of the team involved with the Flying Scotsman restoration.

He said: ‘Every day presents a different challenge and time passes very quickly when you have a lot to think about.’ This was certainly the case when he was faced with machining a replacement cast iron cylinder block, the original being damaged beyond repair.

He added: ‘It’s not like popping down to your local DIY store and buying something off the shelf that is exactly the same.

‘The replacement cylinder block came from a locomotive of the same class as the Flying Scotsman that went for scrap 40 years ago and it is the last of its kind.

‘While it looks the same, the holes that take the securing bolts are not an exact match with those in the engine’s frame.

‘This is significant because each bolt actually functions as a locating dowel as well as a securing bolt and is designed to stop any sideways movement.

‘So, each bolt has to be an interference fit and is knocked into place using a sledge hammer.

‘This means it is vital that the holes in the replacement cylinder block match precisely with those in the engine frame.’ Luckily, nearly all the holes in the replacement cylinder block were smaller than those in the frame, which allowed for slight changes in relative positions to be accommodated while enabling each hole to be machined out to a true circular shape.

In manual machining mode this is a time-consuming process demanding a high level of individual skill, but it is one that benefits from the newly installed DRO capability.

Holmes said: ‘The Heidenhain DRO fitted to the manual lathe has already proved itself in the precision machining of the steel securing bolts, each of which had to be machined so as to provide a precise interference fit.

‘Now, the three-axis DRO fitted to the borer also offers time savings and increased dimensional accuracy of machined parts, while the possibility of error is reduced.’

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