WALLER TABLE ENGINE

By Ramon Wilson

1. Larger scale design built from stock material

This project, a Waller Table engine from circa 1880, began around 1998 when the original model, designed by Anthony Mount, was published in Engineering in Miniature. It was decided to make it one third larger which would give a flywheel of 12" diameter and an overall height including plinth of just under 17".

It's all made from spare material. Apart from the flywheel, which had the rim milled from a flame cut blank and the spoke holes put in at work, all other machining has been done at home. Work was carried out in fits and starts over the years, for much of the time just parts languishing in a box.  As such it's very much been an 'infil' project.

The base and entablature are machined from steel plate. The pads for the columns are separate. Turned from square stock they have spigots that locate holes in the base and are held in place with Loctite then the 'fillets' are applied using JB Weld epoxy steel to give a 'casting' effect. Likewise, the hold down bolt pads. All edges are machined/filed at an angle in an attempt to simulate a draft angle.
The columns are straightforward turnings all the radii formed with form cutters made from ground flat stock.
The cylinder is a composite one with all parts made from a rather tough cast iron cut from a redundant power press baseplate.
The valve face was fixed to the cylinder using a couple of 8BA caphead screws and plenty of JB Weld. This stuff has great strength and a high temperature resistance that will easily take dry steam, though this engine will probably only ever run on air.
JB is a bit runny and slumps a bit so plenty has to be applied but once cleaned up after twenty four hours curing the effect is reasonable enough.
The crank web was milled from solid rather than adding the small web by soldering.
The milling was done on the rotary table after drilling and reaming the two holes for shaft and pin. The part is not just held byt he one visible clamp - which is a definite 'no no' - but is located on a pin in the sub plate.
After finishing, the web was Loctited and cross pinned to the shaft and the crankpin done likewise. The flywheel was found, at this stage, to have a slight wobble so it, being too big to swing in the Myford, was set up on the mill and the bore enlarged. A key-wayed sleeve located by two grub screws fits over the shaft which, after the valve eccentric position has been finalised will also be Loctited.

I spent about a month drilling and tapping most of the holes and finishing off the port face and the steam chest parts and finally making the cross head standards to bring it to the stage shown below. The standards are steel with the guides made from cast iron, let in and fixed with JBW. The slots were milled after bonding and the lower faces then brought square to the slots.