Machining castings in the 4-jaw - knocking?
I am embarking on my first work with castings, a Stuart 10V. I am attempting to do this as described in the 'Vertical Steam Engine' book that came with the kit, that is to say - mounting the castings in the four jaw and facing them using the slowest open gear. I'm getting a nice finish in areas where there is broadly continuous surface, but in the areas of interrupted cuts it's all gone a bit wrong. The four pillars which form the main bearing housing on the baseplate highlight this quite well: https://i.imgur.com/J62yoH0.jpg
Source: model-engineer.co.uk