This article first appeared in Practical Engineering 1940 Vol1 No26. The information that appears within the article is accurate as of 1940. Highlighted are particulars of machines in use by the Industrial sector at the time.
One of the machines that is successfully meeting the present insistent demand for a small-capacity hydraulic horizontal surface grinder capable of producing an extremely high finish with maximum efficiency and accuracy is the Churchill model "N.B." grinder.
The machine is particularly valuable for tool-room work, die grinding, and the surface grinding of small parts under continuous production conditions. Many well-known Churchill features are incorporated in this machine, including the patent "Hydrauto" wheel head bearing adjustment, the Nitralloy steel spindle, fully protected slideways, grinding wheel feed to 0.000lin., work table with variable hydraulic and sensitive hand traverse with instant change to either, and automatic table "run-out" for work inspection and loading.
The grinding-wheel spindle incorporates the Churchill patent "Hydrauto" bearing control, which is so arranged that correct running adjustment is maintained automatically. Whilst only slight pressure is applied, a rigid lock is provided which prevents any movement of the spindle from its true running axis. The "Hydrauto" combination gives a spindle of high precision, coupled with cool running, and one which ensures maximum efficiency under all conditions.
The wheel head is mounted at the top of a column running in slides formed on the body at the rear of the machine. A motor mounted at the foot of the column drives the grinding-wheel spindle by vee ropes, provision being made for adjusting tension. Downfeed to the wheel is given by means of a hand wheel on the front of the machine having a sensitive concentric vernier adjustment reading to 0.000lin. for each wide division. Cross movement of the table is operated by hand or automatically in either direction. A hand-operated concentric vernier adjustment is also provided for this control, making the machine specially useful for all classes of gauge grinding.
The Table Traverse
The hydraulic table traverse can be instantly adjusted to give any speed up to 30ft. per minute. The length of traverse stroke is quickly set by means of two trips on the front of the table, the reversal being absolutely smooth at all speeds. A lever instantly engages hand traverse, and the movement is very sensitive.
The machine is of robust construction, and careful placing of the controls makes operation very simple. The body is a one-piece casting of box section, and the lower portion forms a reservoir for the oil used for the hydraulic traverse mechanism. The oil pump is also in the lower chamber and is belt driven by a motor mounted at the rear of the machine.
Various items of extra equipment are available, such as a tilting workholding fixture either with or without swivelling base, wet grinding equipment, dust exhaust equipment, magnetic chucks, etc.