Power drive from the modified lathe spindle to the drive shafts is by a conventional gear train. Photograph 21 and fig 28 both show the gear train assembled, with the 'banjo' clamped to the drive shaft front bearing housing. Figure 29 details the individual components with Photo 22 showing the completed components. 'Banjo' is the conventional, accepted name for the component labelled on the drawing as 'change gear bracket (79)'. This relatively simple design being more bracket than banjo! The prototype gear train, detailed and described here, is intended for fine feed of cutting tools and screwcutting a limited range of metric thread pitches. The two spindle mounted gears and five change gears, required to meet these requirements are detailed in fig 30. These gears when assembled as fig. 28, and as shown in photo 21, give a tool feed of 0.05mm (approximately two thou.) per spindle revolution. Alternative spindle and change gear assemblies for screwcutting, as fig 30, enable a combination of screw diameter and thread pitch to satisfy any foreseeable modelling needs. Different tool feeds, and screwcutting other metric or imperial threads would probably need modification of the 'banjo' to accommodate any additional gears needed. All machining, drilling and tapping of the components shown on the drawing was relatively straight forward and carried out, where appropriate, on the Myford lathe as before.
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