Sunday, 17 October 2021

Pattern Progress

Having described progress in the last blog on the bits of the engine we already have, this report captures progress on the missing bits. Our pattern making team of Bob Smith and Adam Livingston have had their work cut out.

It might feel like we are getting a bit ahead of ourselves, but firstly here are a few photos of the patterns produced for the spectacle hinges and catches, produced direct from the Kerr Stuart drawings. The somewhat wacky wing nuts are the catches for spectacles. The wings  are eccentric relative to the base. When you unscrew them it releases the spectacle allowing it to rotate.

The bottom hinge, cab38 is similar to the top hinge (cab52) and is formed from the same casting but the slit and wing nut assembly allows the spectacle to be locked in an open position. We are planning on getting these small brass parts cast in the near future to pass on to our home working machinists.

In addition to these brasswork ‘nice to haves’, patternmakers Bob & Adam have been working on the missing ironwork for the engine. 

This is the mould for the fuel filter, part number 852, together with its core boxes:

In this photo of the fuel filter patterns and core boxes, there is some patternmaker/foundryman black art going on. The two core boxes in the centre of the picture fit together so that the sand core can be formed inside them. This core will be used to create the void in the centre of the casting of the filter body. After the mould for the main filter body has been formed in the mould box (on the left), the core is added to occupy the stem area. 

The fuel filter is mounted on the end of the engine block to allow it to be heated by the water.  The void to the water space where the filter mounts is clearly visible on the final photo of the last  blog entry (3rd September 2021) .

Fuel for Diesel engines in the 1920s was not called ‘Diesel’ and to a certain extent they can run on ‘any old shit’, the McLaren running instructions includes some bio-fuel options and references ‘the heater arrangement’ (mounting the filter on the block) to reduce the viscosity of the fuel of choice.


The really big pattern making job is the body for the fuel pump/governor assembly. Some of the drawings being prepared by Will High for this were included in the blog entry made on 16 February 2020. Here is another view of the beast:

This section provides some idea of the internal complexity of it:

Getting to the point of very precisely cutting wood for the pattern has been quite a journey.  The design is derived partly from the body of the MDB2 engine which we have dismantled so that it can reveal its secrets, and partly by taking measurements from the MDB4 engine owned by Armley Mills which we are seeking to replicate.

The MDB2 fuel pump body:

 The fuel pump on the Armley Mills winch:

Patternmaker Bob Smith is seen here with the fruits of his efforts, and those of the camera shy Adam Livingston:

The "balustrade" on the floor to the left of the bench is not going to grace some stately home, this is the main part of the pattern for the core which will form the central void in the casting: 

Imagine this big boy as a huge column of densely packed sand!

This is the pattern for the central portion of the fuel pump body which will house the cams and pushrods operating the pump units; the semi-circular components in the bottom of the photo will support the core.

To say that there has been quite a bit of effort put into creating this one component is something of an understatement, but getting it right from a conservation perspective is an important aspect to the project.

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