What is Entablature ?
The castings are either for:
Individual cylinders bolted together to form the cylinder beam, after machining on the mating surfaces.
They may cast in multi-cylinder units bolted together.
The underside of the cylinder beam should machine. Upon completion, it aligns on the A-frames and fastened in position using fitted bolts.
It is important to remember, the fitted bolts use to bolt the Entablature, A-frames and Bed plate together are for alignment and location purposes only. It is not designed to resist the firing forces, which will tend to separate the three components. In the nutshell, his is the job of the tie bolts.