Colchester CB-1000

The Colchester CB-1000 is the smallest of three CNC bed mills, with travels of 1,070 mm (42.1 in) in X, 510 mm (20.1 in) in Y and 510 mm (20.1 in) in Z. On a bed mill the table moves only in X and Y on a fixed bed while the head carries the vertical axis, so the table can take heavy work without a knee to support. A 140 mm (5.5 in) quill gives a second, manual-style vertical movement for drilling.

The spindle is an ISO 40 taper driven by a 3.7 kW (5.0 hp) inverter motor, with a top speed of 3,600 rpm. Colchester fits heavy duty back gears in the headstock instead of a timing belt for the high and low ranges. That arrangement favours torque at low speed, which is what a 40-taper face mill or a large drill needs, and it explains the modest top speed.

Construction is traditional and heavy. The column, saddle, base and table are stress-relieved Meehanite cast iron. The X slideway is a dovetail and the Y and Z slideways are box ways, coated with Turcite-B, and the slideways, table and T-slots are hardened and ground. The axis drives use 1:2 ratio timing belt pulleys to raise drive torque.

Control is the Fanuc 0i-MF Plus with Manual Guide i, or a Siemens 828D with ShopMill. One caution on size: the specification table and the descriptive text on Colchester's page give different table dimensions for this model, so the table size is left out here until the maker confirms it. There is no tool changer in the specification.