As I have already stated I am putting this to bed until winter forces me out of the workshop.
This is a report on my observations of the engine, the intended design and progress made so far.
First, I am using a print of a drawing at the Science Museum, South Kensington, as the definitive drawing. This was bought over the internet. Although the print contains a lot of detail looking at an actual engine, there is one in the Science Museum, is still a necessity. I believe the Ford Museum has an engine which is not on display. There are the structures of two engines, without moving parts, at Istanbul (I believe the Turks recognise their importance). The print is dated 1838 but I think that this is the engraving date. The Institute of Mechanical Engineers have an earlier drawing which is very similar and L. G. Bateman suggests a date of 1827 for the engine I am copying.
The most imposing part of the model, and the reason to make it, is the actual table structure. All the models I have seen of table engines, except for the one in the Science Museum, Bateman’s and one sold by Christie’s in 2001, use columns to support the table. Compared with Maudslay’s structure columns are easy to make. I have looked at the engine, off and on, over the years and have realised the short faced corner panels carry the load. The nice arched sides are fill-ins and stiffeners. The table has integral beams to support the cylinder. All of these are simple flat castings and are bolted together. The decorations on panels are part of the casting. The panels, table and base were bolted together. After a lot of thought, whether to cast or fabricate, I think the correct course would be to cast in bronze. I have seen far too many poor castings and would consider investment casting just to keep the panel decorations.
The under-table linkages for the steam valve, water pump and air pump look far more complex than they are. The drive to the valve is strange, using a bevel gear. Including these make an interesting model so I would keep them. The crankshaft and eccentric are difficult. The crank should be no more tricky than a multi-cylinder I.C. engine’s. The eccentric is a different matter. The steam valve is rather strange and may not work on a model. It is interesting to note that the Science Museum engine of 1840 has a slide valve.
The print gives a flywheel diameter of 97 inches and my lathe is a Myford Super 7. Therefore a tenth scale model is possible. I started drawing out a model at this scale, not1/13 as stated above, in February. From the beginning I decided that the model would be metric using metric fasteners. The main difficulty met so far is how to attach the panels to the table. My arrangements became more and more complex and illogical. I think, after a rest, a simple arrangement will be found. I have doubts about using metric fasteners, the availability of small fasteners seems to be very restricted.
Below is one a series of drawings produced. It is a .jpeg of a TurboCAD drawing and is not good quality. I was taught how to solid model at work, 20 years ago, using very expensive modelling programs. However my attempts at modelling using TurboCAD have failed dismally so I gave up.
I will post the next progress report in the winter.
AVTUR